ACCOUNT OF HARBOUR PORPOISE (PHOCOENA PHOCOENA) STRANDINGS AND BYCATCHES ALONG THE COAST OF BRITISH COLUMBIA
Robin W. Baird and Tamara J. Guenther
Reports of the International Whaling Commission (Special Issue 16):159-168. 1995.
Little is known about the biology or status of the harbour porpoise (Phocona phocoena) in British Columbia (BC), Canada. In this study, all available records of stranded or incidentally caught harbour porpoise are reviewed. Eighty-one records of stranded animals, or of animals caught in fishing gear along the BC coast, from the period 1934-1991, are presented. The harbour porpoise is the most frequently recorded cetacean stranding on the coast of BC. Stranding records are concentrated where there are large areas of water ranging in depth from 10 to 100m, usually associated with human population centres. Strandings have occurred throughout the year, but biases in effort preclude the determination of any seasonal or geographic trends. Records exist of animals taken incidentally in three commercial fisheries as well as in Canadian government test and research fisheries. Two animals taken incidentally in fisheries in adjacent US waters have also been recovered in BC. In addition, shark predation has been implicated in the death of one individual.
A FEA’S PETREL (PTERODROMA FEAE) OFF NOVA SCOTIA: THE FIRST RECORD FOR CANADA
By Sascha K. Hooker and Robin W. Baird
Birders Journal 6 (5): 245-248. 1997.
Department of Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4J1. Phone: 902 494-3723; Fax: 902 494-3736.
At 1540 hrs on July 7, 1997, while on a research cruise to study Northern Bottlenose Whales Hyperoodon ampullatus in the offshore waters of Nova Scotia, we observed a bird that we had not previously seen in this area. We studied and photographed this individual extensively as it circled the research boat a number of times and landed on the water with a group of Greater Shearwaters Puffinus gravis and Northern Fulmars Fulmarus glacialis. After consulting Harrison (1983), we concluded the bird was a Soft-plumaged Petrel Pterodroma mollis. Upon examination of the photographs taken (examples in Figures 1-3) and after consultation with Ian McLaren (Dalhousie University) and recent published references, it was determined the bird was a Fea’s Petrel P. feae.
Fea’s Petrel is a North Atlantic endemic, and breeds only on the eastern North Atlantic islands of Cape Verde, and on Bugio in the Desertas Islands, Madeira. Until recently, this species was considered a subspecies of the Soft-plumaged Petrel. Three subspecies were recognized in the Soft-plumaged Petrel complex: a southern form, P. m. mollis, and two northern forms, P. m. feae and P. m. madeira (Harrison, 1983). Bourne (1983) proposed that the two northern forms should be considered separate species, resulting in the current recognition of the Soft-plumaged Petrel P. mollisin the southern oceans, and Fea’s Petrel P. feae and Zino’s Petrel P. madeira in the eastern North Atlantic. None of this complex had hitherto been recorded in Canada.
CIRCUMSTANCES OF THE SIGHTING
The individual was sighted at 43°51’N 58°55’W, in the offshore waters of “the Gully”, a submarine canyon which bisects the continental slope some 200 nautical miles (n.m.) east of Halifax, 120 n.m. from the nearest part of mainland Nova Scotia, and 30 n.m. east of Sable Island. The Gully is known for its high diversity of cetacean life, but little research has been conducted on the seabirds there. The water depth in the centre of this canyon (where our observation took place) was 1600 m. The sea-surface temperature at the time of the sighting was 13.6°C, and the air temperature 19.5°C. Temperature over the previous few days had showed no marked increase, although the sea surface temperature was markedly higher than that observed in the Gully during a previous trip to the area (June 9-22nd). Later in the summer (August 14-25th) sea-surface temperature increased to 18 – 19°C. At the time of the sighting there were light westerly winds, good visibility, and a one foot swell. Winds had been generally southwesterly for the previous week, and there had been moderately strong southwest winds (25 – 30 knots) on July 5.
Differentiation of the two North Atlantic species from the Soft-plumaged Petrel is relatively straightforward. Firstly, Soft-plumaged Petrels have a complete dark breast band, whereas the bird we sighted had a partial grey breast-band (Figure 1). Secondly, the uppertail coverts of the Soft-plumaged Petrel are dark grey in colour and the tail is rounded in shape, but our bird had whitish coverts and a wedge-shaped tail (Figure 2). These criteria are sufficient to show that the bird was either a Fea’s or a Zino’s petrel. Differentiation of the two northern species is more problematic, and has been based on small sample sizes. However, Gantlett (1995) and Tove (1997) support certain criteria for differentiating these two species, and we shall use these here.
The upperwing pattern of both Soft-plumaged and Fea’s petrels forms a dark “M”, but is thought to be less distinct in Zino’s Petrel. This “M” pattern was observed in the field (though is not readily apparent in the photographs taken). Wings were long and slender (Figure 1) with a long and narrow “hand” shape (Figure 2). These features are thought to be characteristic of Fea’s Petrel rather than Zino’s Petrel, but are unconfirmed (Tove, 1997). Bill size, however, is listed by all authors who have commented on distinctions as a definitive identifying characteristic: long and heavy in Fea’s Petrel and short and dainty in Zino’s Petrel (and intermediate in the Soft-plumaged Petrel). Figure 3 shows the heavy bill of the individual we saw. We therefore believe that this individual was a Fea’s Petrel. It should be noted that, even if the two North Atlantic petrels become recognised as only subspecifically distinct, the earlier name, Fea’s Petrel, would be retained for the species.
Based on relative population sizes and timing of breeding, Fea’s Petrel would also be more likely to occur in the western Atlantic than Zino’s Petrel. Zino’s Petrels are thought to number only 8-30 breeding pairs, and breed in mid-summer (Fisher 1989, Zonfrillo 1994). Fea’s Petrels are thought to number from 370-430 breeding pairs, with about 300 breeding on the Cape Verde Islands from September or October through about April or May, and 70-130 breeding pairs on Bugio, in the Desertas Islands, Madeira, from July or August through December or January (Cramp and Simmons 1977, Bourne 1983, Harrison 1983, Fisher 1989). In recent years, Fea’s Petrels have been regularly observed off North Carolina (Tove 1997). Sightings have occurred between May and September, most frequently during May and June. Tove (1997) believes these birds to be of the population from Bugio rather than the Cape Verde Islands, both due to the time of year in which they are observed and the lack of flank barring, an apparent feature of the Cape Verde Islands population. The bird we observed showed no obvious flank barring (Figures 1 and 2), suggesting that it may also have been from the Bugio population. The predominately southwesterly winds observed during the week prior, fairly strong a few days prior, to the sighting may have been responsible for appearance of this bird off Nova Scotia.
Ian McLaren helped with many stages of this report, from assistance with identification and literature review to reviewing the manuscript. This sighting took place during research on the Northern Bottlenose Whale by Hal Whitehead’s Research Group, Dalhousie University. Funding for this work is provided by a variety of sources, including the Natural Sciences and Engineering Research Council of Canada, the Whale and Dolphin Conservation Society, World Wildlife Fund Canada, and the Canadian Federation of Humane Societies. Many thanks to crew members who participated in the research. SKH was supported by a Canadian Commonwealth Scholarship. RWB was supported by an NSERC post-doctoral fellowship.
BOURNE, W.R.P. 1983. The Soft-plumaged Petrel, the Gon-gon and the Freira, Pterodroma mollis, P. feae and P. madeira. Bulletin of the British Ornithologists’ Club 103: 52-58.
CRAMP, S. and K. E. L. SIMMONS (eds) 1977. The birds of the Western Palearctic. Vol 1. Oxford University Press, New York.
FISHER, D. 1989. Petrodroma petrels in Madeira. Birding World 2: 283-287.
GANTLETT, S. 1995. Identification forum: field separation of Fea’s, Zino’s and Soft-plumaged Petrels. Birding World 8: 256-260.
HARRISON, P. 1983. Seabirds, an identification guide. Houghton Mifflin Company, Boston.
TOVE, M. Fea’s Petrel in North America. Birding 29: 206-214, 309-315.
ZONFRILLO, B. 1994. The Soft-plumaged Petrel group. Birding World 7: 71-72.
Although these taxonomic changes have been agreed by the AOU, all North American sightings are still presently under review. EDS.
AN EVALUATION OF GRAY WHALE (ESCHRICHTIUS ROBUSTUS) MORTALITY INCIDENTAL TO FISHING OPERATIONS IN BRITISH COLUMBIA, CANADA
Robin W. Baird, Pam J. Stacey, David A. Duffus and Ken M. Langelier
Reports of the International Whaling Commission Special Issue 17: in press.
Abstract: Gray whale (Eschrichtius robustus) mortality incidental to commercial fishing operations in British Columbia (B.C.), Canada was evaluated by two methods: 1) a mail-out questionnaire survey of all commercial fishing licence holders in the province, and 2) a review of records of incidental catches, strandings and dead floating animals from published and unpublished sources. From 5,375 surveys sent out, 848 were returned, a response of 16% Of these, 729 were used in the analysis; the remainder were excluded as incomplete. Forty-two incidents with gray whales were reported, including three mortalities. From sources other than the questionnaire, 41 records of stranded and dead floating gray whales were obtained, of which 4 were judged to have been killed incidental to fishing operations. Twenty-six of these animals had not been examined closely, but extrapolation from the 15 detailed records suggest that 27% of the dead gray whales reported in B.C. die incidentally in fisheries. Collisions with fishing gear are estimated to occur approximately 20 times per year. Mortality occurs in salmon drift gillnet, salmon seine, longline and trap fisheries. There is also one record of an individual entangling and drowning in a herring net pen, as well as an individual entangling in a herring set gillnet. Estimates of annual mortality are approximately 2 individuals using data obtained from the questionnaire, and 2.4 individuals using stranding data. Biases are present for both sampling methods, but the estimated mortality levels are very small relative to population size.
AN INTERACTION BETWEEN PACIFIC WHITE-SIDED DOLPHINS AND A NEONATAL HARBOR PORPOISE
Robin W. Baird
Mammalia 62:129-134. 1998.
An interaction involving two Pacific white-sided dolphins and a neonatal harbor porpoise was observed in eastern Haro Strait, WA, in 1994, and lasted for five hours. On a number of occasions one of the dolphins was observed holding the porpoise’s flipper in its mouth and dragging the porpoise through the water. Both dolphins were observed to occasionally leap on top of the porpoise as it swam at or near the water’s surface. During close approaches of the porpoise to our vessel, one or the other dolphin quickly swam between the porpoise and our boat, and turned away in such a fashion as to force the porpoise away from the boat. Two and one half hours into the observation, a decision was made to capture the porpoise, and the porpoise was captured 2.5 hours later, surviving for five days in captivity. Despite being dragged by its flipper, the porpoise only had superficial skin abrasions on its flippers when captured. Five wounds, consistent with bites, were found on the caudal peduncle. No other trauma was noted, and cause of death was determined to be bacterial pneumonia. Although Pacific white-sided dolphins previously have been reported associating with at least 10 different species of cetaceans, associations with harbor porpoises do not appear to have been previously published. This observation is the first reported of an apparently non-predatory interspecific interaction involving a lone cetacean neonate. Possible causes of the interaction are discussed, including epimeletic behavior, aggressive behavior due to competition, predation or kleptoparasitism, and object-oriented play. In many ways the observations appear similar to object-oriented play (or non-mutual, interspecific play) behavior, with, in this case, the “object” being the harbor porpoise. The function(s) or beneficial effects of “play” in such cases are usually related to physical training or skill development, and this is certainly a possibility in this case.
AN INTERGENERIC HYBRID IN THE FAMILY PHOCOENIDAE
Robin W. Baird, Pamela M. Willis, Tamara J. Guenther, Paul J. Wilson and Bradley N. White
Canadian Journal of Zoology 76:198-204. 1998.
Abstract: A 60-cm female fetus recovered from a Dall’s porpoise (Phocoenoides dalli) found dead in southern British Columbia was fathered by a harbour porpoise (Phocoena phocoena). This is the first report of a hybrid within the family Phocoenidae and one of the first well-documented cases of cetacean hybridization in the wild. In several morphological features, the hybrid were either intermediate between the parental species (e.g., vertebral count) or more similar to the harbour porpoise than the Dall’s porpoise (e.g., colour pattern, relative positioning of the flipper, dorsal fin height). The fetal colour pattern (with a clear mouth-to-flipper stripe, as is found in harbour porpoise) is similar to that reported for a fetus recovered from a Dall’s porpoise off California. Hybrid status was confirmed through genetic analysis, with species-specific repetitive DNA sequences of both harbour and Dall’s porpoise being found in the fetus. Atypically pigmented porpoises (usually traveling with and behaving like Dall’s porpoise) are regularly observed in the area around southern Vancouver Island. We suggest that these abnormally pigmented animals, as well as the previously noted fetus from California, may also represent hybridization events.
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A REVIEW OF CETACEAN AND PINNIPED MORTALITY IN COASTAL FISHERIES ALONG THE WEST COAST OF THE USA AND CANADA AND THE EAST COAST OF THE RUSSIAN FEDERATION
Jay Barlow, Robin W. Baird, John E. Heyning, Kate Wynne, Albert M. Manville, Lloyd F. Lowry, Doyle Hanan, John Sease, and Vladimir N. Burkanov
Reports of the International Whaling Commission Special Issue 15:405-426. 1994.
Abstract: Many passive net fisheries exist along the Pacific coastlines of the USA (California, Oregon, Washington and Alaska), Canada (British Columbia) and the Russian Federation. Some incidental marine mammal mortality occurs in almost all of these fisheries. In this report, we examine 14 of the fisheries from this region that cause marine mammal mortality. The reviews include: (1) a discussion of the relevant laws pertaining to marine mammal mortality in fisheries in each of the three countries, (2) a brief synopsis of the target species and the area and method of operation for the fishery, (3) information on the economic importance of the fishery and the size of recent catches and (4) any available information on the levels of take of cetacean and pinniped species. Less complete, sometimes anecdotal information is provided for a number of other fisheries in this area. For the vast majority of all coastal fisheries along the North Pacific rim, insufficient information is available to determine whether the fisheries are having a negative impact on the species of marine mammals that live in this area. Based on our findings for this area, we make four recommendations for the gathering of additional information to evaluate the significance of fishery mortality on marine mammal populations and to help minimize its impact
A REVIEW OF KILLER WHALE INTERACTIONS WITH OTHER MARINE MAMMALS: PREDATION TO CO-EXISTENCE
Thomas A. Jefferson, Pam J. Stacey and Robin W. Baird
Mammal Review 21:151-180. 1991.
Killer whales are well-known as predators of other marine mammals, including the large sperm and baleen whales. Members of all marine mammal families, except the river dolphins and manatees, have been recorded as prey of killer whales; attacks have been observed on 20 species of cetaceans, 14 species of pinnipeds, the sea otter, and the dugong. Ecological interactions have not been systematically studied and further work may indicate that the killer whale is a more important predator for some populations than previously believed. Not all behavioural interactions between killer whales and other marine mammal species result in predation, however. Some involve ‘harassment’ by the killer whales, feeding by both species in the same area, porpoises playing around killer whales, both species apparently ‘ignoring’ each other, and even apparently unprovoked attacks on killer whales by sea lions. These non-predatory interactions are relatively common. We conclude that interactions between killer whales and marine mammals are complex, involving many different factors that we are just beginning to understand.
A REVIEW OF RECORDS OF STRIPED DOLPHINS (STENELLA COERULEOALBA) FROM CANADIAN WATERS
Robin W. Baird, Sascha K. Hooker, Hal Whitehead, and Roger Etcheberry
Paper SC/49/SM4 presented to the IWC Scientific Committee, September 1997.
We review all known published and unpublished records of striped dolphins (Stenella coeruleoalba) in Canadian waters. Sixty records (representing 42-43 occurrences) from the Atlantic coast and 13 records (representing 12-13 occurrences) from the Pacific coast are presented. The 11 records from eastern Canada prior to 1989 include five strandings (four single and one mass), three sightings, and two to three kills in fishing operations. Atlantic records since 1989 are primarily sightings in one area, occurring every summer that substantial research effort has been expended. This area, termed the Gully, is a deep-water canyon which bisects the continental slope, and appears to be part of the regular range of this species. An analysis of sightings in relation to effort in that area showed that striped dolphins were concentrated in deep water areas, at times with particularly high sea surface temperature. On average, group sizes are small (mean = 16) compared to elsewhere in their range, and associations with other species of cetaceans appear to occur more frequently in this area (40% of sightings). Stranding records from eastern Canada have primarily occurred in late-fall and winter. The presence of two near-term fetuses in animals which stranded in November suggest that calving in the western North Atlantic may occur in early-winter. Most records from the Pacific coast are strandings of single individuals occurring in winter/spring. Considering the difference between seasonality of strandings (winter) and sightings (summer) off eastern Canada, and the bias of research towards shallow, inshore waters, it is unclear whether striped dolphins should be considered extra-limital off the Pacific coast. Considering their deep water habits, this species is likely more common in Canadian waters than records indicate. Only a few records of mortality in fishing operations exist, and none in recent (since 1988) years.
BEHAVIORAL REACTIONS OF NORTHERN BOTTLENOSE WHALES TO BIOPSY DARTING AND TAG ATTACHMENT PROCEDURES
Sascha K. Hooker, Robin W. Baird, Sa’ad Al-Omari, Shannon Gowans and Hal Whitehead. 2001.
Fishery Bulletin 99: 303-308.
The effects of invasive or intrusive research techniques need to be thoroughly documented in order to satisfy appropriate standards of animal care. How cetaceans react to either biopsy darting or tag attachment procedures has been studied for several species, and considerable interspecific variability in responses has been demonstrated; however, few studies have compared reactions to both techniques. In the family Ziphiidae (the beaked whales) nothing has previously been reported on responses to either technique. We examined and compared the reactions of northern bottlenose whales (Hyperoodon ampullatus) to biopsy darting and tagging. Reactions to both these procedures were generally low-level and short-lived; stronger responses were given to hits than to misses. There was no statistical difference in observed response to tag versus biopsy hits. The prior behavioral state of the whales appeared to influence the magnitude of reaction to both hits and misses and thus may be an important factor to consider in impact assessment. Whales lying still at the surface showed stronger reactions than traveling or milling animals. Sea state appeared to affect whether there was a reaction to misses. Whales were more likely to respond to a miss in calm sea conditions. No avoidance of the research vessel was observed following a tag or biopsy attempt, and in most cases whales re-approached the research vessel again within several minutes.
CETACEAN STRANDINGS AND BYCATCHES IN NOVA SCOTIA, EASTERN CANADA, 1991 – 1996.
Sascha K. Hooker, Robin W. Baird, and Mark A. Showell
Paper SC/49/O5 presented to the IWC Scientific Committee, September 1997.
Sixty-five records of cetacean strandings around the coast of mainland Nova Scotia between 1991 and 1996 are reported. Ten species are represented in the stranding records, including: Atlantic white-sided dolphin, Lagenorhynchus acutus (6 events, 31 individuals); long-finned pilot whale, Globicephala melas (5 events, 13 individuals); minke whale, Balaenoptera acutorostrata (4 events, 4 individuals); fin whale, Balaenoptera physalus (4 events, 4 individuals); sperm whale, Physeter macrocephalus (3 events, 4 individuals); humpback whale, Megaptera novaeangliae (3 events, 3 individuals); right whale, Eubalaena glacialis (1 event, 1 individual); northern bottlenose whale, Hyperoodon ampullatus (1 event, 1 individual); harbour porpoise, Phocoena phocoena (1 event, 1 individual); and bottlenose dolphin, Tursiops truncatus (1 event, 1 individual). Species identification of an additional 39 individuals from 36 events could not be confirmed. Strandings occurred year-round, with a mid- to late-summer peak in reports, due primarily to effort. The majority of strandings (60) involved single animals; Atlantic white-sided dolphins, long-finned pilot whales, and sperm whales were recorded to mass strand. One hundred and twelve records (representing 120 individuals) of cetaceans incidentally killed in fisheries in Nova Scotia waters are also presented (based on an observer program on larger vessels). Kills have been recorded in bottom trawl (99 events), longline (9 events), midwater trawl (3 events) and purse seine (1 event) fisheries. Long-finned pilot whales (72 individuals) and Atlantic white-sided dolphins (6 individuals) comprise the majority of incidentally caught animals.
DALL’S PORPOISE REACTIONS TO TAGGING ATTEMPTS USING A REMOTELY-DEPLOYED SUCTION-CUP TAG
M. Bradley Hanson and Robin W. Baird
Marine Technology Society Journal 32(2):18-23. 1998.
Remotely-deployable non-invasive (suction-cup attached) tags to record underwater behavior of cetaceans have recently been developed. How useful these tags are for applications on a broad range of species has yet to be documented however. We attempted to use such tags to study the diving behavior of Dall’s porpoise (Phocoenoides dalli) in the trans-boundary area of British Columbia and Washington state, and report here on the feasibility of the technique, including the reactions of Dall’s porpoise to tagging attempts. Tagging activities were undertaken in August 1996, while porpoises were bow-riding on a small vessel. Fifteen tagging attempts were made, 13 of which resulted in tag contact with a porpoise. No reactions were observed for the two misses, nor for 2 of the 13 hits. Of the 11 cases when tag reactions were observed, porpoises returned to continue bowriding almost immediately in 7 cases, suggesting no long-term effect. Short-term reactions observed included a flinch (9 of 13 hits), tailslap (1 of 13 hits) and high speed swimming away from the vessel (4 of 13 hits), with some hits resulting in more than one type of reaction. Three of 13 hits resulted in successful tag attachment. One tag remained attached for 41 minutes, providing the first diving behaviour data for this species. Rates of descent and ascent, as well as swimming velocity, were relatively high only for the first 6-8 minutes after tag attachment, suggesting a reaction to tagging that lasted approximately 8 minutes.
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DEEP-DIVING BEHAVIOUR OF THE NORTHERN BOTTLENOSE WHALE, HYPEROODON AMPULLATUS (CETACEA: ZIPHIIDAE)
Sascha K. Hooker and Robin W. Baird. 1999.
Proceedings of the Royal Society, London. B. 266: 671-676.
Using suction-cup attached time-depth recorder/VHF radio tags, we have obtained the first diving data on northern bottlenose whales (Hyperoodon ampullatus), the first such data on any species within the family Ziphiidae. Two deployments in 1997 on northern bottlenose whales in a submarine canyon off Nova Scotia demonstrated their exceptional diving ability, with dives approximately every 80 min to over 800 m (maximum 1453 m), and up to 70 min in duration. Sonar traces of non-tagged, diving bottlenose whales in 1996 and 1997 suggest that such deep dives are not unusual. This combined evidence leads us to hypothesize that these whales may make greater use of deep portions of the water column than any other mammal so far studied. Many of the recorded dives of the tagged animals were to, or close to, the sea floor, consistent with benthic or bathypelagic foraging. A lack of correlation between dive times and surface intervals suggests that the dives were predominately aerobic.
DIVING AND NIGHT-TIME BEHAVIOUR OF LONG-FINNED PILOT WHALES IN THE LIGURIAN SEA
Robin W. Baird, J. Fabrizio Borsani, M. Bradley Hanson and Peter L. Tyack
Marine Ecology Progress Series 237:301-305 (2002).
ABSTRACT: Pilot whales (Globicephala spp.) have long been thought to be deep divers, yet little information is available on dive depths. During August 1999 we obtained detailed dive data from suction-cup-attached time-depth recorder/VHF radio tags deployed on five long-finned pilot whales (G. melas). Pilot whales were tagged for short periods (average 5 hours per individual) in deep (>2000 m) waters of the Ligurian Sea, off the northwest coast of Italy. During the day all five whales spent their time in the top 16 m of the water column, and visible surface activities consisted primarily of rest and social behaviours. Tags remained attached after dark on two whales, and shortly after sunset both whales made several deep dives (max. 360 and 648 m). Velocity on these deep dives was greater than during shallow dives either during the day or at night, suggesting that these deep dives function primarily for foraging. Our results confirm the supposition that long-finned pilot whales can dive deep, particularly within 2 h after sunset, which is the time that vertically migrating prey become more readily available as they move closer to the surface.
DIVING AND RANGING BEHAVIOUR OF ODONTOCETES: A METHODOLOGICAL REVIEW AND CRITIQUE
Sascha K. Hooker and Robin W. Baird
Mammal Review 31: in press. 2001.
Abstract: Movements can be analysed in terms of horizontal or vertical dimensions, but cetacean movement is ultimately three-dimensional, and it is the integration of analyses of both horizontal and vertical movements that will provide the most insight about an animal’s behaviour. Current field techniques can provide simultaneous information on both diving (vertical movements) and ranging (horizontal movements). We shall discuss the considerations, techniques and analyses for diving and ranging studies, together with the advantages and disadvantages of each technique. Ranging studies using VHF or satellite-linked radio-transmitters have evolved alongside studies of diving behaviour using time-depth recorders, and problems associated with deployment and attachment techniques apply to both. The diving (and concurrent ranging behaviour) of thirteen species of odontocetes has been studied using time-depth recorders or acoustic transponders with VHF- or satellite-transmitters. However, differences in sampling techniques used, and summary statistics presented, have made comparisons difficult. We review these issues and suggest parameters that should be presented in future studies of diving and ranging. In general, studies should be consistent in their presentation of the basic parameters and statistics, and provide enough information for the reader to assess the limitations of the data.
DIVING BEHAVIOUR OF FALSE KILLER WHALES OFF MAUI AND LANA’I, HAWAII
Allan D. Ligon and Robin W. Baird
In Abstracts of the 14th Biennial Conference on the Biology of Marine Mammals, Vancouver, Canada, December 2001.
Cetacean dive depths are sometimes inferred from knowledge of the habits of their prey. For false killer whales an early published report suggested they might dive to 500 m, based upon general feeding habits. However, dive depths have not previously been documented for this species. In Hawaiian waters, this species has been observed feeding on fish such as mahimahi and yellowfin tuna, which spend most of their time in surface waters. We hypothesize that such observations are biased towards surface-oriented prey, and false killer whales are also likely feeding at depth. During 1999 and 2001, we deployed three suction-cup attached time-depth recorder/VHF radio tags on this species around Maui and Lana’i, Hawaii, obtaining just over 16 hours of depth/velocity data. Dives were relatively shallow (maximum 22, 52 and 53 m, average from 8 – 12 m) and were not limited by bottom depth. Regressions of dive depth versus duration for all whales were positive, however the r-squared values were relatively low (0.07 – 0.55), suggesting that dive shape is highly variable (and dive duration cannot be used as a predictor of dive depth). A comparison of day and night dive parameters (depth, duration, velocity) for one whale showed some differences, however dive parameters suggested foraging both during the day and at night. In general, the dive depths of the three false killer whales were shallow relative to depths documented for several smaller species of odontocetes, suggesting that diving behaviour is likely driven more by ecology than body size. Given the relatively shallow depth profile of the whales our hypothesis was not supported. Although a larger sample size would be preferred, our results suggest that surface-based observations of predation may be relatively unbiased for this species in near-shore Hawaiian waters.
DIVING BEHAVIOUR OF KILLER WHALES
Robin W. Baird, Lawrence M. Dill and M. Bradley Hanson
Page 9 in Abstracts of the World Marine Mammal Science Conference, Monaco, January 1998.
Like all cetaceans, killer whales spend the vast majority of their time beneath the water’s surface, where they are invisible to observers. However, behavioural studies on killer whales have routinely described and quantified their activities based only on surface behaviours, with no discussion of whether such behaviours are indicative of subsurface activities. Similarly, studies of behaviour have taken place almost exclusively during daylight hours, with no examination of diurnal patterns. This study investigated the subsurface behaviour and night-time activities of killer whales in southern British Columbia (Canada) and in northwestern Washington state (USA) from 1993 through 1997, using suction-cup attached time-depth recorder (TDR)/VHF radio tags. Through June 1997 these tags have been deployed on 13 occasions, 12 on so-called “resident” killer whales and one on a so-called “transient” killer whale, with a total of 77 hours of TDR data. Depth was recorded once per second, and for 6 deployments (in 1996 and 1997) velocity was recorded every 5 seconds. Tag attachment ranged from 15 minutes to 22 hours. Although the sample size is small, several consistent behavioural features have been observed. All “resident” killer whales spent the vast majority of their time (>70%) in the upper 20 m of the water column, where salmon (thought to be their primary prey) are concentrated. However, during periods when they were considered to be foraging, all “residents” dove occasionally to 100 m or more (maximum recorded dive depth of 201 m), and we suspect these deep dives reflect regular feeding on bottom and mid-water fish. An examination of night-time diving parameters (maximum depth, variability in depth, dive shape/profile, rate of ascent and descent, and velocity) suggest that resting may occur much more frequently at night than during the day. Diving parameters from the single “transient” differed from those of all “residents”, possibly due to differences in prey species, since “transients” feed primarily on harbour seals. The combined data suggest that studies of killer whale behaviour must take into account subsurface activities in order to provide an accurate representation of habitat use and diurnal activity patterns.
ECOLOGICAL AND SOCIAL DETERMINANTS OF GROUP SIZE IN TRANSIENT KILLER WHALES
Robin W. Baird and Lawrence M. Dill
Behavioral Ecology 7:408-416. 1996.
Most analyses of the relationship between group size and food intake of social carnivores have shown a discrepancy between the group size that maximizes energy intake and that which is most frequently observed. Around southern Vancouver Island, British Columbia, killer whales of the so-called transient form forage in small groups, and appear to prey exclusively on marine mammals. Between 1986 and 1993, in approximately 434 h of observations on transient killer whales, we observed 138 attacks on 5 species of marine mammals. Harbor seals were most frequently attacked (130 occasions), and the observed average energy intake rate was more than sufficient for the whale’s energetic needs. Energy intake varied with group size, with groups of three having the highest energy intake rate per individual. While groups of three were most frequently encountered, the group size experienced by an average individual in the population (i.e., typical group size) is larger than three. However, comparisons between observed and expected group sizes should utilize only groups engaged in the behavior of interest. The typical size of groups consisting only of adult and sub-adult whales that were engaged primarily in foraging activities confirms that these individuals are found in groups that are consistent with the maximization of energy intake hypothesis. Larger groups may form for: 1) the occasional hunting of prey other than harbor seals, for which the optimal foraging group size is probably larger than three; and 2) the protection of calves and other social functions.
Key Words dispersal, foraging, group hunting, harbor seals, killer whales, optimal group size, social structure.
FIRST RECORDS OF FALSE KILLER WHALES, PSEUDORCA CRASSIDENS, IN CANADA
Robin W. Baird, Ken M. Langelier, and Pam J. Stacey
Canadian Field-Naturalist 103:368-371. 1989.
A stranding of an adult male false killer whale (Pseudorca crassidens) on Denman Island, British Columbia, on 3 May 1987, was the first record for Canada. Stomach content analysis revealed small numbers of parasites (Anisakis sp.) and recent predation on salmon (Oncorhynchus sp.) and squid (either Berryteuthis magister or Gonatopsis borealis). Osteological evidence and tooth dentine-layer counts (26 growth layer groups) indicate an individual of advanced age. Tissue analysis for heavy metals and pesticides revealed very high levels of mercury (liver, 728 ppm wet weight) and DDE (blubber, 1400 ppm wet weight). A group of at least 12 other P. crassidens remained in the inshore waters of Puget Sound, Washington from 3 May 1987 to 2 July 1987, one of which stranded and died. A single individual P. crassidens was photographed in Johnstone Strait, B.C., on 22 June 1987, and a different individual P. crassidens live-stranded in Ucluelet, B.C., on 28 July 1987, and was returned to the water.
Stacey, P.J., and R.W. Baird. 1991. Status of false killer whales, Pseudorca crassidens, in Canada. Canadian Field-Naturalist 105:189-197.
FLUCTUATIONS IN DISTRIBUTION AND PATTERNS OF INDIVIDUAL RANGE USE OF NORTHERN BOTTLENOSE WHALES
Sascha K. Hooker, Hal Whitehead, Shannon Gowans and Robin W. Baird. 2002.
Marine Ecology Progress Series 225:287-297.
This study investigated the pattern and scale of distribution, movements and range use of northern bottlenose whales (Hyperoodon ampullatus) above a submarine canyon off eastern Canada between 1988-1998. Locations and individual identification photographs were collected during encounters with whales. Whales showed a discrete distribution within the canyon, which was associated with water depth (500-1500m) and relatively steep topography. Encounter rate and distribution showed some variation between years. Changes in distribution were observed toward the north or south of the canyon, likely a consequence of changes in prey distribution. Individual whales within the canyon displaced 4-5 km over 24 hr, with negligible further increase in displacement over time scales up to 20 days (their approximate residency period). Short-term VHF radio-tracking of five individuals provided an independent source of movement data, showing displacements of approximately 2 km in one hour and 5-10 km in one day. The relative lack of movement observed for these whales supports the hypothesis that the canyon contains a profitable and localized foodsource. Movements of whales best fit a model of short-term residence within a discrete range of approximately 25-km2 area, although the range size of mature males was smaller than that of females and immature males. Photo-resightings were also used to investigate variation of positions of individual whales within the Gully. Within years, individuals showed some separation of ranges associated with periods of high whale abundance, but there was no separation between different age-sex classes. Between years, mature males showed consistent spatial orientations relative to one another, suggesting preferred locations possibly related to mating opportunities.
LEVELS OF ORGANOCHLORINE COMPOUNDS, INCLUDING PCDDS AND PCDFS, IN THE BLUBBER OF CETACEANS FROM THE WEST COAST OF NORTH AMERICA
W.M. Jarman, R.J. Norstrom, D.C.G. Muir, B. Rosenberg, M. Simon, and R.W. Baird
Marine Pollution Bulletin 32:426-436. 1996.
Abstract: Levels of organochlorine compounds (PCDD, PCDF, PCB and organochlorine pesticides) were determined in cetceans collected from the west coast of North America between 1986 and 1989. The samples included gray whale (Eschrichtius robustus), killer whale (Orcinus orca), false killer whale (Pseudorca crassidens), Risso’s dolphin (Grampus griseus) and Dall’s porpoise (Phocoenoides dalli) collected in British Columbia, and harbour porpoises (Phocoena phocoena) collected in British Columbia and central California. TCDD and TCDF levels ranged from 1 to 8 nm per kg and 2.0 to 209 ng per kg, respectively. The highest levels of PCDDs were found in the harbour porpoises; the levels of 1,2,3,6,7,8-HxCDD in the samples from Victoria, Campbell River and Qualicum River were 128, 128 and 62 ng per kg, respectively. Five other 2,3,7,8-substituted dioxins and dibenzofurans were detected in the cetaceans at levels ranging from 1 to 10 ng per kg. In addition to the 2,3,7,8-substituted congeners, several non 2,3,7,8-substituted congeners were detected. The patterns of the PCDDs and PCDFs in the British Columbia porpoises were consistent with implication of chlorophenols as the source of the PCDDs and PCDFs, which were either present in wood chips used in bleached kraft paper mills, or came from direct contamination by chlorophenols. No PCDDs or PCDFs were detected in the California samples. One false killer whale sample had exceptionally high levels of DDT compounds (1700 mg per kg DDE, 120 mg per kg DDT and 40 mg per kg o,p’-DDT) and toxaphene (89 mg per kg). PCB levels in the cetaceans were highest in the false and killer whales (22 to 46 mg per kg GM), and lowest in the Risso’s dolphin (1.7 mg per kg). Levels of DDE in the British Columbia harbour porpoises were 6.0 mg per kg, and probably reflect the accumulation of global background levels of DDE.
OBSERVATIONS OF SOWERBY’S BEAKED WHALES (MESOPLODON BIDENS) IN THE GULLY, NOVA SCOTIA
Sascha K. Hooker and Robin W. Baird. 1999.
Canadian Field-Naturalist 113(2): 273-277.
Little is known about most members of the family Ziphiidae, the beaked whales. Sowerby’s Beaked Whale (Mesoplodon bidens) is known from only a handful of sightings and strandings; few descriptions of group composition or surfacing behaviour are available. During 1997 and 1998, groups of Sowerby’s Beaked Whales were observed in the Gully, a submarine canyon off eastern Canada, on four occasions. Sightings were in water depths of between 550 and 1500 m. Group size varied from 3 to 8-10 individuals. A mixed composition group was observed on one occasion, consisting of at least two female-calf pairs and two to four adult males (based on the presence of visible teeth and extensive scarring). Another group consisted of three quite heavily-scarred and therefore presumably male animals. Whales were observed to dive for between 12 and 28 minutes. Blows were either invisible or relatively inconspicuous. During all surfacings the long beak projected from the water well before the rest of the head or back was visible. While surfacing behaviour was generally unremarkable, one individual tail-slapped repeatedly.
OBSERVATIONS ON THE REACTIONS OF SEA LIONS, ZALOPHUS CALIFORNIANUS AND EUMETOPIAS JUBATUS, TO KILLER WHALES, ORCINUS ORCA; EVIDENCE OF “PREY” HAVING A “SEARCH IMAGE” FOR PREDATORS
Robin W. Baird and Pam J. Stacey
Canadian Field-Naturalist 103:426-428. 1989.
Observations on the reactions of California sea lions (Zalophus californianus) and Steller sea lions (Eumetopias jubatus) to the presence of foraging transient killer whales (Orcinus orca) were made on three occasions. Alert and avoidance responses by sea lions were made in the presence of killer whales of typical appearence. In the presence of a single, foraging killer whale of atypical appearance, no alert or avoidance response was observed. It is possible that the sea lions did not recognize the atypical whale as a killer whale, suggesting that sea lions may have a perceptual “search image” for the detection of predators, based on visual cues.
OCCURRENCE AND BEHAVIOUR OF TRANSIENT KILLER WHALES: SEASONAL AND POD-SPECIFIC VARIABILITY, FORAGING BEHAVIOUR AND PREY HANDLING
Robin W. Baird and Lawrence M. Dill
Canadian Journal of Zoology 73:1300-1311. 1995.
We studied the occurrence and behaviour of so-called transient killer whales (Orcinus orca) around southern Vancouver Island from 1986 to 1993. Occurrence and behaviour varied seasonally and among pods; some pods foraged almost entirely in open water and were recorded in the study area throughout the year, while others spent much of their time foraging around pinniped haul-outs and other near-shore sites, and used the study area primarily during the harbour seal (Phoca vitulina) weaning/post-weaning period. Overall use of the area was greatest during that period, and energy intake at that time was significantly greater than at other times of the year, likely due to the high encounter rates and ease of capture of harbour seal pups. Multi-pod groups of transients were frequently observed, as has been reported for “residents”, but associations were biased towards those between pods which exhibited similar foraging tactics. Despite the occurrence of transients and residents within several kilometres of each other on nine occasions, mixed groups were never observed and transients appeared to avoid residents. Combined with previous studies on behavioural, ecological and morphological differences, such avoidance behaviour supports the supposition that these populations are reproductively isolated.
ORCA SURVEY FIELD GUIDE TO TRANSIENTS OF THE HARO STRAIT AREA
Astrid M. van Ginneken, David K. Ellifrit and Robin W. Baird
Center for Whale Research, Friday Harbor, WA. 1998.
This catalogue of 75 transient killer whales documented in the Haro Strait area is available for a small cost from the Center for Whale Research, P.B. Box 1577, Friday Harbor, WA 98250 (e-mail: firstname.lastname@example.org)
Introductory text from the catalogue is presented below.
This “field guide to transient killer whales in the Haro Strait area” differs from the Orca Survey “field guide to southern resident killer whales” in several ways. While more than 75 individual transients have been documented in this area over the last 20 years, only about 20 specific individuals use this area almost every year. Many of the other individuals in this guide have only been seen on one or two occasions. Those individuals which are seen most frequently are presented in the first few pages. All of these whales form part of a much larger “community” of transient killer whale, which range from California north to Alaska. Unlike residents, transients typically travel in small groups, ranging from lone animals (usually adult males) to temporary aggregations of up to 15 or more individuals. The usual size of a transient group is 2-4 individuals. Like residents, many of the transient groups are very stable, but some dispersal of individuals occurs from transient groups. Hence, the presence of several individuals in one grouping in this catalogue should not imply that these individuals are always seen together. Similarly, when an individual disappears from its group, it may not be possible to tell whether that individual has died or dispersed (see below). Thus, this catalogue contains all transients documented from this area, even though some of these individuals have not been seen anywhere throughout their known range for many years (e.g., Q7, Y2, M1). The naming system for transients is less straight-forward than for residents; in fact, since transients range along the entire Pacific Northwest coast, individuals have been given names by several different research groups, and we have tried to include these names when known. This naming system is arbitrary, that is, two individuals which share a common letter designation are not necessarily related.
POSSIBLE INDIRECT INTERACTIONS BETWEEN TRANSIENT AND RESIDENT KILLER WHALES: IMPLICATIONS FOR THE EVOLUTION OF FORAGING SPECIALIZATIONS IN THE GENUS ORCINUS
Robin W. Baird, Peter A. Abrams and Lawrence M. Dill
Oecologia 89:125-132. 1992.
Two distinct forms of killer whale (Orcinus orca) occur off the coast of British Columbia, Alaska and Washington State. These have different diets, and may be reproductively isolated. Because the primary food of transient whales (pinnipeds) is a potential competitor for the primary food of resident whales (salmon), or for the smaller fishes on which salmon feed, there should be an indirect interaction between the two forms of killer whale. We use simple mathematical models to show that this interaction will be either of a “plus-minus” type, or a “plus-plus” type (indirect mutualism), depending on whether or not pinnipeds and residents are on the same trophic level. In the case of the “plus-minus” interaction, increasing the population density or improving the environmental conditions of transients will increase the population density of residents, while increasing resident populations will reduce the equilibrium population size of transients. In the case of the “plus-plus” interaction, increasing the population density or improving the environmental conditions of transients will increase the population density of residents, and vice versa. Such effects may not be currently manifest due to reduced populations at most levels in the food web. Regardless, considering such indirect interactions may be important for the management of many of the species involved, and can also provide a valuable framework for examining the evolution of the two forms of killer whales. Frequency-dependent indirect interactions, acting in concert with density-dependence within populations and disruptive selection on prey-type specific foraging characteristics, may have favoured reproductive isolation of the two forms of killer whales. We suggest that these two forms of whale are in the process of speciating, i.e., the two forms are incipient species.
REACTIONS OF BOTTLENOSE DOLPHINS TO TAGGING ATTEMPTS USING A REMOTELY-DEPLOYED SUCTION-CUP TAG
Karsten Schneider, Robin W. Baird, Steve Dawson, Ingrid Visser and Simon Childerhouse
Marine Mammal Science 14:316-324. 1998.
In order to study the diving behaviour of bottlenose dolphins in Doubtful Sound, New Zealand, the authors attempted to tag bowriding dolphins with a suction-cup attached time-depth recorder/VHF radio tag. The note describes the immediate reactions of both tagged individuals and other dolphins within the same group, as well as the behaviour of the dolphins when they were encountered on subsequent days. A total of 17 tagging attempts were made between 24 and 29 October 1995. The tag contacted a dolphin in 10 cases, and remained attached for > 10 seconds in five of these. In each of the five cases in which the tag contacted and stuck, the tagged animal immediately began a bout of high-energy behaviours, apparently to dislodge the tag. Tags remained attached on these dolphins for periods of about 10 seconds to about three minutes. Group speed and the number of leaps in the group increased in 5/5 and 4/5 of these cases, respectively. In general, reaction intensity decreased in the order: successful attachments > unsuccessful attachments > misses. Within several days of initiating tagging attempts, the frequency of bowriding behaviour in the population decreased, and slowly returned to “normal” over the next two months. Based on both the reactions exhibited by individual dolphins and those in the surrounding group, and on the inability of the suction-cup tag to remain attached during leaps and high speed swimming, the authors suggest that suction-cup tagging of this population of bottlenose dolphins is not feasible. Reactions of bottlenose dolphins were substantially greater than have been observed for similar studies using these tags on killer whales and Dall’s porpoise.
SIGHTINGS, STRANDINGS AND INCIDENTAL CATCHES OF SHORT-FINNED PILOT WHALES, GLOBICEPHALA MACRORHYNCHUS, OFF THE BRITISH COLUMBIA COAST
Robin W. Baird and Pam J. Stacey
Reports of the International Whaling Commission Special Issue 14:475-479. 1993.
Records of the short-finned pilot whale, Globicephala macrorhynchus, from within the Canadian 320 km (200 mi) extended economic zone off the coast of British Columbia, are presented, with a total of 19 occurrences to 1989. Six animals were incidentally caught in Canadian waters in an experimental driftnet fishery for flying squid (Ommastrephes bartrami) in 1986-7, and an additional five animals were taken by this fishery outisde of Canadian waters in 1983-7. This fishery has now been discontinued. Sighting records are infrequent. Water depth at sighting and incidental catch localities ranged from 10 to 1,200 fathoms. Mean group size was about 15, with a range from 1 to 150 individuals (n=15). Single individuals were sighted most frequently. Records have been obtained from April through October but since search effort in winter months is greatly reduced, it is difficult to determine if this distribution reflects seasonal change in their presence in BC waters. Although there are large gaps in the sighting record (1962-76, 1978-84), it can probably be assumed that the increased number of records in recent years is due to an increase in search and recording effort. Based on this information the short-finned pilot whale should be considered rare in the waters off British Columbia. They may be present in these waters in most years, but usually only with a few records each year. Sighting programs are limited, and no information is available on sightings per unit effort.
SIGHTINGS AND STRANDINGS OF BEAKED WHALES ON THE WEST COAST OF CANADA
Pamela M. Willis and Robin W. Baird
Aquatic Mammals 24:21-25. 1998.
Summary: Sightings and strandings of beaked whales from British Columbia were compiled. A total of 42 records were compiled, 21 of Cuvier’s beaked whales (18 strandings, one sighting, one incidental catch), seven Hubbs’ beaked whales (all strandings), five Stejneger’s beaked whales (all strandings), four Baird’s beaked whales (three sightings and one stranding), and six records where species could not be confirmed. One of the stranded animals identified only to the genus Mesoplodon was an approximately 2-m long animal with erupted teeth in the middle of the mandibles. This combination of features does not match the description of any known species of Mesoplodon. The only incidental catch record was of a Cuvier’s beaked whale killed in a fishery for flying squid in offshore waters. A 30.4-cm fetus was recovered from a pregnant Hubbs’ beaked whale which stranded on 2 October 1992.
SOCIAL ORGANIZATION OF MAMMAL-EATING KILLER WHALES: GROUP STABILITY AND DISPERSAL PATTERNS
Robin W. Baird and Hal Whitehead
Canadian Journal of Zoology 78:2096-2105. 2000
The social organization of mammal-eating “transient” killer whales (Orcinus orca) was studied off southern Vancouver Island from 1985 through 1996. Strong and long-term associations exist between individual transients, so sets of individuals with consistently high association levels, termed pods, can be delineated. Pods consist of individuals of mixed ages and sexes, and typically contain an adult female and one or two offspring (averaging 2.4 individuals). The mother-offspring bond remains strong into adulthood for some male (and less often for female) offspring. Other males disperse from their maternal pod and appear to become “roving” males, spending some of their time alone, and occasionally associating with groups that contain potentially reproductive females. These males appear to have no strong or long-term relationships with any individuals, and adult male – adult male associations occur significantly less often than expected by chance. Females that disperse from their natal pod appear to be gregarious (having high average association rates) but socially mobile (having low maximum association rates). Differences in social organization from the sympatric fish-eating “resident” killer whales (where no dispersal of either sex occurs) likely relate to differences in foraging ecology. Transient killer whales maximize per capita energy intake by foraging in groups of three individuals, whereas no such relationship has been documented for resident killer whales.
STATUS OF THE BOTTLENOSE DOLPHIN, TURSIOPS TRUNCATUS, WITH SPECIAL REFERENCE TO CANADA
Robin W. Baird, Eric L. Walters and Pam J. Stacey
Canadian Field-Naturalist 107:466-480. 1993.
The bottlenose dolphin (Tursiops truncatus) is distributed worldwide in warm temperate and tropical waters. This report reviews the general biology, worldwide status and management of this species, with special reference to its status in Canadian waters. More is known about the biology of bottlenose dolphin than perhaps any other cetacean. No estimates of worldwide population size exist, although there are numerous estimates for specific regions. Two forms are recognized, coastal and offshore; they are distinguishable through a wide variety of characteristics. The species is not threatened, although the population in the Black Sea is currently considered at risk. In some areas, bottlenose dolphins are taken deliberately in drive fisheries, and they are caught incidentally in fishing operations worldwide. Levels of pollutants recorded in this species are among the highest recorded for any cetacean. The bottlenose dolphin is rare in Canadian waters, where it is at the northern limits of its range. Twenty-two records from eastern Canada, representing only 11 occurrences, are presented. Future records from the Canadian east coast may be less frequent, as an apparently natural die-off in the population off the north east coast of the U.S. in 1987-1988 may have resulted in a population reduction of over 50%. We know of no confirmed records from western Canada, although a stray animal from the inshore waters of Washington State has recently been recorded, and there are historical records from an Indian midden from the outer Washington coast. A single unconfirmed record from offshore British Columbia water exists.
STATUS OF FALSE KILLER WHALES, PSEUDORCA CRASSIDENS, IN CANADA
Pam J. Stacey and Robin W. Baird
Canadian Field-Naturalist 105:189-197. 1991.
The false killer whale (Pseudorca crassidens) occurs at the northern limits of its range and is rare in Canadian waters. There are 23 confirmed records, totalling 10 occurrences from British Columbia, but none are reported from the east coast of Canada. General biology, world-wide status and management are reviewed. Little information is available on stocks or population estimates, but the species is not uncommon world-wide. The false killer whale is taken in small numbers in whaling and incidentally in fisheries. Strandings occur frequently and may significantly affect the levels of local populations. The effects of long-term degredation of its environment and subsequent impact on its populations are potentially serious and should be monitored.
Baird, R.W., K.M. Langelier and P.J. Stacey. 1989. First records of false killer whales, Pseudorca crassidens, in Canada. Canadian Field-Naturalist 103:368-371.
STATUS OF KILLER WHALES IN CANADA
Robin W. Baird
Contract report submitted to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Reviewed and evaluated by COSEWIC in April 1999. Published in the Canadian Field-Naturalist in 2001. Download an Adobe PDF version of this report at ResearchGate
Killer whales can be found in all three of Canada’s oceans, as well as occasionally in Hudson Bay and in the Gulf of St. Lawrence. Little is known about their occurrence or biology in the Atlantic or Arctic, but killer whales appear to be uncommon in most parts of these areas. In the Canadian Arctic and western Atlantic small numbers were killed historically in commercial whaling operations (or shot incidentally to such operations), and small numbers have been documented taken by natives. Predictable concentrations of killer whales are found in British Columbia (B.C.), and populations in B.C.’s nearshore waters are among the most well-known populations of cetaceans world-wide. Killer whales off the Pacific coast can be classified into two distinct “types” or “forms” (termed residents and transients), which differ in diet (residents feed on fish, transients feed on marine mammals), morphology, genetics and behaviour. The exact taxonomic relationship between these two types is unclear, though some authors have termed them “races”, others consider them separate species. Regardless, from both a scientific and management perspective these populations should be treated as distinct. Within B.C. waters residents appears to be sub-divided into three geographic communities or populations (termed the “northern” and “southern” residents, and “offshore” killer whales), based on association patterns, genetics and morphology. Relatively little is known of the “offshore” population of killer whales. All populations (including transients and the three resident populations) are small (in the low hundreds), and have low potential rates of increase. No trend information is available for “offshore” or transient killer whales. The “northern” resident population has been growing steadily in size since the 1970s (when live-capture fisheries stopped and shooting declined), while the “southern” resident population has been growing only sporadically, and is currently smaller than the pre-live-capture population estimate from the 1960s. Given the small population sizes and their low potential rates of growth, killer whales are potentially at risk from anthropogenic influences in two primary ways: due to immunotoxic affects of persistent toxic chemicals (levels in “southern” residents are three times higher than levels known to cause immunotoxicity in harbour seals), and due to a reduction in prey availability. It is also possible that the large and growing commercial and recreational whale watching industry on the west coast may be having an impact, though such impacts are as yet unclear. In terms of natural factors, periodic events such as mass strandings or entrapments in narrow inlets or ice have the potential to drastically reduce local populations. Since virtually all of these factors should impact killer whales throughout Canadian waters, all populations, at the least, should be classified by COSEWIC as Vulnerable, that is, as “species of special concern because of characteristics which make them especially sensitive to human activities or natural events”. As the “southern” resident population is extremely small (89 individuals in 1998), has declined by 10% in the last three years due to an increase in mortality rates (primarily of adult females), is more subject to anthropogenic influences than other populations, and these influences are not expected to decrease in the foreseeable future, it should be listed as Threatened by COSEWIC. Further research, particularly on Arctic, Atlantic and “offshore” populations, is clearly needed.
Portions of the text of this report can be found here:
Introduction, Population Discrimination etc
Special Significance and Evaluation
STATUS OF MARINE MAMMALS IN THE STRAIT OF GEORGIA, PUGET SOUND, AND THE JUAN DE FUCA STRAIT, AND POTENTIAL HUMAN IMPACTS
John Calambokidis and Robin W. Baird
Canadian Technical Report of Fisheries and Aquatic Sciences 1948:282-300. 1994.
Abstract: Nine species of marine mammals commonly occupy the trans-boundary waters of British Columbia and Washington (BC/WA). Individuals of all species move across this international border. Of the four pinniped species common to these waters, harbour seals are the most numerous and the only one that breeds in the trans-boundary area. Approximately 27,000 harbour seals occur in the trans-boundary area, and the population has been increasing at 5-15% per year. Elephant seals are found in the trans-boundary area in small numbers, and their occurrence in the area has increased in recent years. The number of California sea lions in the area increased in the 1980s and appears to have stabilized. While declining through most of its range, the number of Steller sea lions which use this area appears to be stable, although well below historical levels. Of the five cetacean species common to the waters, harbour and Dall’s porpoise are the most abundant and number in the several thousands. Harbour porpoise numbers in some areas have declined since the 1940s, though little data are available to assess current trends in populations of these two species. Two populations of killer whales utilize the trans-boundary area. The “resident” population is growing and is currently larger than it was prior to a live-capture program in the 1960-70s. Over 20,000 gray whales migrate past the entrance to the Strait of Juan de Fuca and some individuals spend prolonged periods feeding in the spring and summer in BC/WA waters. A small number of minke whales use this area for feeding, primarily during the spring, summer, and fall.
Marine mammal are vulnerable to human activities in the BC/WA trans-boundary waters. High concentrations of contaminants, especially chlorinated hydrocarbons and some metals, have been identified in these animals. Highest concentrations of contaminants have been found in harbour seals (from southern Puget Sound), harbour porpoise and killer whales. Determination of the impacts of these contaminants on marine mammals in these waters has been inconclusive, though in other areas contaminant exposure has been linked to reproductive failure and immunosuppression. Marine mammals are killed incidental to commercial fishing operations, particularly harbour porpoise and Dall’s porpoise. Information to assess human impacts on most marine mammals and to adequately evaluate their current status is extremely limited.
STATUS OF THE PACIFIC WHITE-SIDED DOLPHIN, LAGENORHYNCHUS OBLIQUIDENS, IN CANADA
Pam J. Stacey and Robin W. Baird
Canadian Field-Naturalist 105:219-232. 1991.
The Pacific white-sided dolphin (Lagenorhynchus obliquidens) appears to be an abundant permanent resident of the pelagic waters off the west coast of Canada and a regular visitor to inshore waters. This report summarizes the general biology and management of this species with special reference to its status in Canada. One hundred and fifty- six records from Canada’s 320 km (200 mile) extended economic zone are presented. Group size ranges from 1 to 1000, with a mean, median and modal size of 62, 15 and 6 respectively. Depth of water from sighting locations ranges from 10 to 2000 fathoms, with mean, median and modal depths of 617, 400 and 100 fathoms, respectively. Sea surface temperature taken at 73 record locations had a range from 6 degrees to 17 degrees C, with a mean, median and mode of 12 degrees, 13 degrees and 15 degrees C respectively. The Pacific white-sided dolphin is taken directly and incidentally in small numbers in fisheries throughout its range. From 1985 through 1987 a total of 14 (four of which were released alive) were caught in an experimental driftnet fishery for flying squid (Ommastrephes bartrami) in offshore Canadian waters, the second most frequent incidentally taken cetacean. Small numbers are also taken incidentally in net fisheries in British Columbia, but a lack of comprehensive recording of net-induced mortality makes determination of the extent of this catch or its impact on populations difficult. Based on sighting records, the number of Pacific white- sided dolphins in Canadian waters is probably high. Exact determination of status, especially population trends, cannot be made at this time. With the presumed lack of serious threats, however, and until further studies elucidate population numbers and trends, the Pacific white- sided dolphin should be considered not in jeopardy and therefore not in any COSEWIC category.
STATUS OF THE RISSO’S DOLPHIN, GRAMPUS GRISEUS, IN CANADA
Robin W. Baird and Pam J. Stacey
Canadian Field-Naturalist 105:233-242. 1991. Download Adobe PDF copy from USGS science base
In the eastern North Pacific and the western North Atlantic, the Risso’s dolphin(Grampus griseus) reaches its northern limits in Canadian waters, and is rare in Canada. General biology, world-wide status and management are reviewed. Twenty-one records from Canadian waters are presented. Records from the Pacific coast of Canada are from throughout the year and show no seasonal trends. Little information is available on stocks or population estimates, but Risso’s dolphins are not uncommon worldwide. They are taken only in small numbers in whaling and incidentally in fisheries. The effects of longterm degredation of its environment and subsequent impact on its populations are potentially serious and should be monitored.
STATUS OF THE SHORT-FINNED PILOT WHALE, GLOBICEPHALA MACRORHYNCHUS, IN CANADA
Pam J. Stacey and Robin W. Baird
Canadian Field-Naturalist 103:481-489. 1993. Download Adobe PDF copy
The short-finned pilot whale, Globicephala macrorhynchus, appears to be in the northern limits of its normal range in the waters off British Columbia, and does not inhabit the waters off the east coast of the country. No COSEWIC designation is required regarding its status in Canadian waters. World-wide, one population of short-finned pilot whales, off northern Japan, is currently considered at risk. Insufficient information is available to accurately evaluate its status elsewhere, and it is taken in small numbers both directly and incidentally in fisheries.
STATUS OF THE STRIPED DOLPHIN, STENELLA COERULEOALBA, IN CANADA
Robin W. Baird, Pam J. Stacey and Hal Whitehead
Canadian Field-Naturalist 107:455-465. 1993.
The striped dolphin, Stenella coeruleoalba, is found in offshore waters throughout the world in warm-temperate and tropical seas. Large numbers are killed yearly in directed fisheries off Japan and they are also incidentally caught in fishing operations around the world. Published and unpublished records from Canadian waters include 11 from western and 17 from eastern Canada. The striped dolphin appears to be at the northern limits of its normal range in Canadian waters, and no serious threats to it exist here. No COSEWIC status designation is required.
STATUS OF THE NORTHERN RIGHT WHALE DOLPHIN, LISSODELPHIS BOREALIS, IN CANADA
Robin W. Baird and Pam J. Stacey
Canadian Field-Naturalist 105:243-250. 1991.
The northern right whale dolphin, Lissodelphis borealis, is one of the most abundant oceanic dolphins in its range in the North Pacific, but little is known about its biology or distribution. The biology and management of this species are summarized with special reference to its status in Canadian waters. Seventeen occurrences of the northern right whale dolphin from within the Canadian 320 km (200 mile) extended economic zone are presented; only one occurrence has been previously published. Seven of these records are of animals killed in a Canadian experimental flying squid (Ommastrephes bartrami) driftnet fishery in 1986 and 1987, which has since been discontinued. Lack of comprehensive recording of sightings, strandings and incidental catches render the exact status of this species in Canadian waters unclear. Based on the best available information, the northern right whale dolphin is rare in Canadian waters, where it is in the outermost limits of its normal distribution.
THE STATUS OF THE DWARF SPERM WHALE, KOGIA SIMUS, IN CANADA
Pamela M. Willis and Robin W. Baird
Canadian Field-Naturalist 112:114-125. 1998.
Abstract: The dwarf sperm whale, Kogia simus, has been recorded in tropical and warm temperate waters world-wide. This species is rarely observed at sea, and little is known of its biology. Insufficient information is available to classify its world-wide status, though they are infrequently taken directly and indirectly in various fisheries. In Canada, the only confirmed record is of a single stranded animal from Vancouver Island, British Columbia, though they are likely found in Canadian waters more frequently. There are no obvious threats to its status in Canadian waters where the species is not at risk.
THE STATUS OF THE PYGMY SPERM WHALE, KOGIA BREVICEPS, IN CANADA
Robin W. Baird, Dawn Nelson, Jon Lien and David W. Nagorsen
Canadian Field-Naturalist 110:525-532. 1996.
Abstract: The general biology, world-wide status and management of pygmy sperm whale, Kogia breviceps, with special reference to its status in Canadian waters, is reviewed. Pygmy sperm whales appear to be uncommon in Canadian waters; there are several unconfirmed sighting records off British Columbia and only four stranding records off the Canadian east coast. Little is known about its biology or world-wide status, and although it is taken in small numbers both directly and incidentally in fisheries, no serious threats to its status are apparent. No COSEWIC designation is required regarding its status in Canadian waters.
SUBSURFACE AND NIGHTTIME BEHAVIOUR OF PANTROPICAL SPOTTED DOLPHINS IN HAWAI’I
Robin W. Baird, Allan D. Ligon, Sascha K. Hooker, and Antoinette M. Gorgone. 2001.
Canadian Journal of Zoology 79: 988-996
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Pantropical spotted dolphins are found in both pelagic waters and around oceanic islands. A variety of differences exist between populations in these types of areas, including average group sizes, the extent of movements, and the frequency of multi- species associations. Diving and night-time behaviour of pantropical spotted dolphins were studied near the islands of Maui and Lana’i, Hawaii in 1999. Suction-cup attached time-depth recorder/VHF radio tags were deployed on six dolphins for a total of 29 hours. Rates of movements of tagged dolphins were substantially lower than reported in pelagic waters. Average diving depths and durations were shallower and shorter than reported for other similar-sized odontocetes but were similar to those reported in a study of pantropical spotted dolphins in the pelagic waters of the eastern tropical Pacific. Dives (defined as > 5 m deep) at night were deeper (mean = 12.8 m, SD = 2.1, n = 2 individuals, maximum 213 m) than during the day (mean = 57.0 m, SD = 23.5, n = 4 individuals, maximum 122 m), and swim velocity also increased after dark. These results, together with the series of deep dives recorded immediately after sunset, suggest that spotted dolphins around Hawaii feed primarily at night on organisms associated with the deep scattering layer, as it rises up to the surface after dark.
THE KILLER WHALE – FORAGING SPECIALIZATIONS AND GROUP HUNTING
Robin W. Baird
Chapter 5 in Cetacean Societies: Field Studies of Dolphins and Whales. Edited by J. Mann, R.C. Connor, P.L. Tyack and H. Whitehead. University of Chicago Press. 2000. 432 p.
Introduction: Among the cetaceans, killer whales (Orcinus orca – Figure 6.1) exhibit several unusual features related to social organization, ecology and behavior. Perhaps the most striking are dispersal patterns. For two so-called “resident” populations in the eastern North Pacific (numbering about 200 and 89 individuals, respectively, as of 1998), neither sex has been recorded dispersing (neither locational nor social dispersal – cf. Isbell and van Vuren 1996) from their natal groups over a 21 year period, nor has immigration into a group been recorded (Bigg et al. 1990a). Natal philopatry by both sexes has not been positively documented for any other population of cetacean, or for that matter, for any other species of mammal. Individuals from “resident” populations feed on fish, and individuals from another, sympatric population, termed “transients,” specialize on marine mammal prey. These two forms were termed resident and transient based on research in the 1970s (Bigg et al. 1976; Bigg 1982). These names have been subsequently shown to not be particularly descriptive of the movement patterns and site fidelity of the two forms (Guinet 1990; Baird et al. 1992), but they have been retained as the common names. One apparent consequence of the differences in diet are differences in dispersal patterns. Resident killer whales travel in long-term stable groups comprised of several maternal lineages (Bigg et al. 1990a). However, among transients, all female offspring and all but one male offspring seem to disperse from their maternal groups (social dispersal), but dispersing offspring continue to use their natal range (locational philopatry) (Baird 1994). Besides the difference in diet, resident and transient killer whales also differ in behavior, acoustics, morphology, pigmentation patterns, and genetics (Table 6.1, Figure 6.2). Foraging specializations appear to occur in killer whale populations elsewhere, though research efforts have been generally insufficient to determine whether, similar to the N. Pacific, sympatric forms specialize on different prey types. Individuals of some southern ocean populations feed almost exclusively on marine mammals (Hoelzel 1991; Guinet 1991a; Baird et al. 1992). Predation on marine mammals makes the study of foraging behavior easier than perhaps for any other species of cetacean, because the prey are large, breathe at the surface, and are often captured close to, or even on shore. Several interesting findings have come from these studies, including apparent teaching of hunting skills to offspring (Lopez and Lopez 1985; Guinet 1991b; Hoelzel 1991), and also a strong relationship between group size and foraging success in one population (Baird and Dill 1996). Other studies have demonstrated features for killer whales which appear to be unusual among mammals in general, including the presence of some females who live 20 or more years beyond the birth of their last known offspring (Olesiuk et al. 1990), and the occurrence of group-specific vocal dialects within killer whale populations (Ford and Fisher 1983; Strager 1995). In this paper I review the general biology of killer whales, focusing on several longitudinal studies on free ranging animals. Information on feeding habits, ranging patterns, and social organization and behavior are emphasized.
VARIATION IN SADDLE PATCH PIGMENTATION IN POPULATIONS OF KILLER WHALES (ORCINUS ORCA) FROM BRITISH COLUMBIA, ALASKA AND WASHINGTON STATE
Robin W. Baird and Pam J. Stacey
Canadian Journal of Zoology 66:2582-2585. 1988.
Patterns of pigmentation of the post dorsal fin patch, or saddle patch, were analyzed from photographs of 372 resident and 99 transient killer whales (Orincus orca) from British Columbia, Alaska, and Washington State. Of the five types of saddle patch analyzed, all were observed on residents, but only two occurred on transients. Differences in saddle patch shapes were independent of age and sex. Saddle patch pigmentation patterns were similar among clans within a community. Pigmentation patterns differed significantly between the resident and transient forms, between northern and southern residents, between northern and Alaskan residents, and between southern and Alaskan residents. As the saddle patch shape may be heritable to a large degree, these differences suggest genetic isolation of the populations. If so, this technique may be used to delineate stocks of killer whales from other areas.
YELLOW-FOOTED GULL (LARUS LIVENS) PREYS ON A BLACK STORM-PETREL (OCEANODROMA MELANIA)
Robin W. Baird
Colonial Waterbirds 19:260-261. 1996.
I observed a Yellow-footed Gull (Larus livens) capture an apparently healthy Black Storm-Petrel (Oceanodroma melania) near a breeding colony of petrels in the Bay of La Paz, Baja California Sur, Mexico. The petrel was caught after it left the colony, approximately 75 m from shore, when it was forced to the water’s surface by the gull, and apparently consumed. This represents the first report of a Yellow-footed Gull killing a storm-petrel, as well as the first record of larid predation on Black Storm-Petrels. It is unusual also, because the petrel was captured at sea, rather than directly on a breeding colony.
Key words. – Yellow-footed Gull, Larus livens, Black Storm-Petrel, Oceanodroma melania, predation.
Predation on storm-petrels at seabird colonies has been recorded on numerous occasions. However, actual observations of predation are rare. Most records of predation are indirect, usually obtained through analysis of stomach contents, pellets, or remains collected from predators (e.g., gulls, owls and falcons – French 1979, Trapp 1979, Vermeer et al. 1988, but see Watanuki 1986, Ryan and Moloney 1991). Predation by diurnal predators is believed to exert selection influencing the development of nocturnal behaviour in storm-petrels at colonies, with birds usually approaching and departing from colonies at night (cf. Lockley 1932, Harris 1974, Watanuki 1986). Here I describe an incident of Yellow-footed Gull (Larus livens) predation on a Black Storm-Petrel (Oceanodroma melania).
On February 14, 1996, at approximately 0840 hrs local time, a Black Storm-Petrel was seen leaving Los Islotes, a small pair of islands in the Bay of La Paz, Baja California Sur, Mexico. This site is a breeding colony of both Black Storm-Petrels and Yellow-footed Gulls. As at other storm-petrel colonies, petrels are rarely seen close to shore in daylight hours at this site (pers. obs.). The storm-petrel was observed at close range (within 5 m) flying about 2-3 m above the water’s surface quickly away from shore, and was first seen approximately 20 m from shore. Within several seconds, two Yellow-footed Gulls flew out from the island about 3 m above the water’s surface, and began chasing the petrel, catching up with it and quickly forcing it to the water’s surface when about 75 m from shore. One of the gulls grabbed the petrel in its mouth, almost completely engulfing it. Both gulls then flew back to the islands, landing out of sight behind several large boulders. Although actual ingestion was not observed, I presume that the gull swallowed the storm-petrel.
This observation is of interest for several reasons. First, Yellow-footed Gull predation on storm-petrels does not appear to have previously been reported in the literature, although this species has been recorded capturing and killing other bird species (Dunning 1988, Verlarde 1992). Similarly, predation by any larids on Black Storm-Petrels does not appear to have been previously reported. Secondly, this capture occurred over water and away from a colony, demonstrating that gulls are, at least under some circumstances, able to capture free-flying storm- petrels. According to Harrison (1983) it is not possible to discriminate juvenile from adult Black Storm-Petrels. As the storm-petrel left the island it flew quickly and directly away, suggesting a healthy individual. The possibility remains, however, that this particular individual was a juvenile and not experienced with avoidance of predators and/or that it not healthy and was therefore unable to easily avoid capture by the gulls. Observations of potential avoidance behavior by storm- petrels at sea, when storm-petrels and gulls are in the same vicinity, would help clarify whether such possibilities were factors in this incident.
This observation was made while working with Special Expeditions, Seattle, WA, on board a tender from the MV Sea Lion. I would like to thank D. Anderson, A. Burger, G. McChesney and R. Podolsky for helpful suggestions or leads to references, as well as D. Anderson and an anonymous reviewer for comments on the manuscript.
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Harris, S.W. 1974. Status, chronology, and ecology of nesting storm petrels in northwestern California. Condor 76:249-261.
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Lockley, R.M. 1932. On the breeding habits of the storm-petrel, with special reference to its incubation and fledging-periods. British Birds 25:206-211.
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Trapp, J.L. 1979.Variation in summer diet of Glaucous-winged Gulls in the western Aleutian Islands: an ecological interpretation. Wilson Bulletin 91:412-419.
Verlarde, E. 1992. Predation of Heermann’s Gull (Larus heermanni) chicks by Yellow-footed Gulls (Larus livens) in dense and scattered nesting sites. Colonial Waterbirds 15:8-13.
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