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Polar Biol 2000) 23: 675678 Springer-Verlag 2000 ORIGINAL PAPER Andrew E. Derocher ystein Wiig Georg Bangjord Predation of Svalbard reindeer by polar bears Accepted: 26 March 2000 Abstract Polar bears Ursus maritimus) are believed to bernicla hrota) Madsen et al. 1989), Canada geese be obligate predators on marine mammals, and partic- B. canadensis) Smith and Hill 1996), thick-billed mur- ularly, on two species of seals. This paper reports on res Uria lomvia) Donaldson et al. 1995), willow ptar- observations of polar bears preying n 7) and scav- migan Lagopus lagopus) Miller and Woolridge 1983) enging n 6) on Svalbard reindeer Rangifer tarandus and vegetation Russell 1975; Derocher et al. 1993). platyrhyncus). Similar to their closest evolutionary The distribution of polar bears, when on land, over- ancestor, the brown bear U. arctos), polar bears are laps with that of two large terrestrial mammals, reindeer opportunistic and will prey on ungulates. Reindeer are Rangifer tarandus) and muskox Ovibos moschatus). likely of minor importance to the foraging ecology of While polar bears have beenreported to feed onreindeer polar bears in Svalbard, but the observations suggest and muskox in Greenland Pedersen 1945), there is only behavioural plasticity in response to a novel prey item. one report of a polar bear killing an ungulate. A trapper in Greenland found a dead muskoxen, still warm, that was thought to have been killed by a polar bear seen in the area Pedersen 1945). In this paper, we report on observations of predation Introduction and scavenging of Svalbard reindeer R. t. platyrhyncus) by polar bears. The polar bear Ursus maritimus) is a specialized pre- dator and preys primarily on ringed seals Phoca hisp- ida), bearded seals Erignathus barbatus) and harp seals Materials and methods P. groenlandica) Ln 1970; Stirling and Archibald 1977; Smith 1980). Polar bears are opportunistic, how- Study area ever, and commonly prey on other marine mammals such as white whales Delphinapterus leucas) Smith We collected observations of seven predation events and six in- 1985; Lowry et al. 1987), narwhal Monodon monoceros) stances of scavenging by polar bears on Svalbard reindeer between Smith and Sjare 1990) and walrus Odobenus rosmarus) 1983 and 1999. The study was conducted in the Svalbard Archi- pelago located in the western Barents Sea between 74 and 81N Calvert and Stirling 1990). Polar bears also will feed on and 10 and 35E. Observations of predation and scavenging of a wider range of species including little auks Alle alle) Svalbard reindeer were obtained during eld operations of a re- Stempniewicz 1993), pale-bellied brent geese Branta search program designed to assess the population dynamics and ecology of polar bears in southeast Svalbard. In addition, obser- vations were obtained from individuals working or travelling in Svalbard. For observations other than those of the authors, we A. E. Derocher &) have identied the observers of each incident. Norwegian Polar Institute, 9296, Troms, Norway e-mail: derocher@npolar.no Tel.: +47-7775-0524, Fax: +47-7775-0501 Results . Wiig Zoological Museum, On 1 April 1999, a polar bear was observed on land near University of Oslo, Sars gate 1, 0562, Oslo, Norway Ingeborgfjellet 7740N, 14E) walking into the wind R. Eide). The bear's head was held high, moving from G. Bangjord Odden, 7057, Jonsvatnet, Norway side to side as if sning the air. The bear moved out of 676 sight and, when next seen, was 5600 m away and was dragging a fresh reindeer carcass that left a large blood trail. Given the cold temperatures during this observa- tion, the reindeer had either died very recently or was killed by the bear. After 2 days on the carcass, the bear left and was observed chasing a small reindeer herd. No additional reindeer were captured. The area near Inge- borgfjellet, where the reindeer were feeding, is very steep. In the same period that the polar bear was seen with the reindeer, two reindeer were observed with broken legs, presumably from a fall on the cli. Injured reindeer would be much easier prey for polar bears than healthy individuals. On 6 March 1998, fresh polar bear tracks, estimated to be 6 h old, were observed near Kapp Bjrset, Sval- bard 7750N, 1330E) J.D. Bulens and P. Bulens-van Spronsen). The tracks led to a fresh reindeer carcass, believed to have been killed by a polar bear. The loca- tion had been passed the previous day and no signs of the bear or the reindeer were seen. A polar bear had also fed onan older reindeer carcass that was observed a few hundred meters away. A sleeping pit at the site suggested the bear had rested overnight at the kill location. On 14 March 1998, again at Kapp Bjrset, following Fig. 1 Adult male polar bear with freshly killed 10-month-old a recent snowfall, an adult male polar bear ca. 300 kg) reindeer, Kapp Bjrset, Svalbard photograph, G. Bangjord) was observed lying along the land-sea edge with a freshly killed adult male reindeer. Blood and tracks indicated that the reindeer and polar bear had struggled over an approached the island directly across the at, land-fast area of 10 m radius. The body of the reindeer was still sea ice. She may have smelled the reindeer bedded on the warm. The polar bear had just started to feed on the edge of Delitschya approximately 10 m from the sea carcass whenobserved. The polar bear ed the kill upon ice. The female circled behind the reindeer, approached seeing the observer and then swam in an arc into the from the top of the island, and captured the reindeer slush ice, landing back on shore ca. 60 m from where it while it was lying. The carcass was partially consumed entered the water. It snied the air and watched the but still unfrozen when examined. The bears had a observer. It then moved further onto land and started to bedding area about 10 m from the carcass. run. Approximately 20 m in front of the bear, a snow- InMarch/April 1996, tracks of a polar bear were seen covered reindeer jumped up and ran away. The bear that suggested a successful predationevent inColesdalen continued running until it stopped with forelegs sti 78N, 15E) L. Aby). It appeared that the polar bear and stood quietly over another reindeer, a 10-month-old slowly approached downhill towards a reindeer that was calf, which was almost totally snow covered. Details of lying in a shallow snow bed. It appeared that the bear how the reindeer was killed were not observed. After less made a short dash at the reindeer and killed it with than a minute, the bear carried the calf by the neck for minimal struggle. a distance of about 200 m Fig. 1). The bear fed on In late March 1995, in the pass between Ringdalen the carcass but retreated to the sea againwhendisturbed and Tufsdalen 7803N, 1544E) at 500600 m above and did not return to feed on it. However, the bear sea level and about 20 km from the coast, tracks were was observed 4 h later feeding on the rst adult male observed of a polar bear travelling northward through reindeer with which it had been observed. Several 4050 cm of fresh snow S. Onarheim). The tracks led other freshly killed reindeer were observed in the same directly to a dead reindeer carcass that was still warm area later in March and April 1998, after the above and about half consumed by a polar bear estimated at observations. 23 years of age. Signs indicated no struggle. The feed- On 9 April 1997, while conducting eld ecology ing area covering a 10 m 10 m area. It was thought studies of polar bears in Svalbard, a fresh set of polar that the polar bear killed the reindeer while it was bear tracks was observed and followed for approxi- sleeping. mately 5 km to Delitschya 7723N, 2231W), which Inmid-March 1992, a polar bear was observed eating lies a few hundred meters from the larger Edgeya. a reindeer at Dune rbukta, 7810N, 19E), about 600 m A kill site of an adult reindeer was observed from the from shore at 100 m above sea level S. Onarheim). The air. An adult female polar bear 15 years old) and two bear was present at the site for at least a day based on yearling cubs were captured at the site. From recon- recent weather patterns. The bear had a sleeping pit and struction of the tracks in the area, the female eating area at the site but recent snow had obscured all 677 tracks. Most of the reindeer had been eaten but lack of mented, we have estimated A.E. Derocher and . Wiig, freezing suggested the reindeer had died recently or was personal observation) from eld studies during capture killed. Other reindeer were present in the area during procedures, a top speed near 3040 km/h. The Svalbard both sightings. reindeer is a recognized sub-species characterized by Polar bears have been frequently observed scavenging short legs, thick fur and the ability to store large reindeer. On 17 September 1998, an adult female amounts of fat Krog et al. 1976). Leg length in reindeer 13 years old) believed to be pregnant was captured near relates to nutritional stress, energetic eciency of for- the carcass of a dead reindeer on Firneheia, Edgeya, aging through snow of varying depths, eciency of 10 km from the coast. Fragments of esh and hair be- locomotion, and eetness in relation to predator tween the female's teeth indicated that she had been avoidance Klein et al. 1986). Svalbard reindeer can feeding on the reindeer. In this instance, a female with reach speeds up to 60 km/h on a good running surface, two 9-month-old cubs and another single bear were but under deep snow conditions, cannot exceed speeds observed near the carcass. On 8 April 1997, an adult of about 20 km/h N.A. ritsland, personal communi- female 11 years old) with two cubs-of-the-year ca. cation). Precipitation in Svalbard is typically less than 4 months old) were located at a maternity den site on 400 mm per year Norwegian Hydrographic Service Edgeya feeding on a reindeer carcass just outside the 1990) and strong winds keep the snow thin in most den. The following day, an adult female 7 years old) near-shore areas. The dearth of observations of polar and two cubs-of-the-year were found on land on Edge- bears chasing reindeer is consistent with the ability of ya feeding on another reindeer carcass. In the same Svalbard reindeer, usually, to easily escape when aware area, a bear was tracked from the sea ice onto land of the bear. where the bear dug a reindeer carcass from the snow and The Svalbard reindeer population is likely regulated fed on it. In April 1983, two dierent polar bears were by adverse climatic conditions that restrict access to observed on Edgeya coming o the sea ice and scav- food during the winter/spring Reimers 1977). All in- enging reindeer carcasses N. A. ritsland). In one case, stances of polar bear predation on reindeer occurred the bear returned to the sea ice with the carcass. during the winter/spring season when some reindeer may be weakened and are easier prey. Further, opportunities for scavenging by polar bears are higher during spring when more reindeer die. Female polar bears with young Discussion cubs emerging from dens in March/May have undergone an extended winter fast and food resources are critical Polar bears of both sexes and all age classes are common for cub survival Watts and Hansen 1987; Derocher and near shore in Svalbard and frequently cross over land Stirling 1996). Therefore, reindeer carcasses may present moving between fjords A.E. Derocher and . Wiig, an important food source for some mothers. unpublished data). Svalbard reindeer are distributed Polar bears often hunt seals by stalking quietly close throughout the Svalbard Archipelago with a total pop- to a seal lying on the snow or up to a ringed seal in a lair, ulation size of ca. 11,000 ritsland and Alendal 1986). using vision and scent to locate the prey, and subse- Approximately 60% of Svalbard is covered by glaciers quently make a short dash or pounce into snow covering and most of the vegetation is found from the tidal zone the lair Stirling 1974). The hunting of reindeer was to 200 m above sea level Mehlum 1990). Therefore, similar to methods polar bears use on seals. All instances Svalbard reindeer are often located near shore or in of predation occurred on reindeer that were lying in valleys where they are more likely to encounter polar snow-covered areas, and in at least one case, the reindeer bears. was snow covered. During snow-free times of the year, The Svalbard reindeer have been isolated on Svalbard polar bears are more visible, resulting in greater di- for ca. 20,00040,000 years Hakala et al. 1986). There culty in stalking reindeer. Polar bears are thought to are no wolves Canis lupus) or indigenous humans in have evolved from brown bears U. arctos) Kurte n Svalbard and Svalbard reindeer have evolved with little 1964), which can prey on reindeer and caribou, moose or no predation. Svalbard reindeer were frequently ob- Alces alces) and elk Cervus elaphus) Cole 1972; Boertje served to approach polar bears and may not consider et al. 1988; Young and McCabe 1997). Adult Svalbard them as predators. Absence of common terrestrial pre- reindeer weigh between 41 and 57 kg Krog et al. 1976), dators may have reduced vigilance behaviour and similar in size to adult ringed seals, but are small prey increased vulnerability to occasional predation by polar relative to other ungulates. Lack of struggle at the ob- bears. served killed sites suggests that reindeer are easily killed Body size and energetics were postulated as signi- if captured by polar bears. cant factors governing how bears of dierent body size On Wrangel Island, Russia, it was reported that polar hunt ungulates Stirling and Derocher 1990). In partic- bears were only able to catch sick reindeer incapable of ular, larger bears hunt by stalking close to their prey and running Belikov 1976). Ln 1970) stated that while then make a short rush, while smaller bears may be able polar bears and reindeer in Svalbard often meet, he to sustain longer chases Stirling and Derocher 1990). and winter trappers in Svalbard found no evidence of While the running speed of polar bears is undocu- polar bears killing reindeer. We cannot determine if the 678 Kurte n B 1964) The evolution of the polar bear, Ursus maritimus incidence of polar bear predation and scavenging on Phipps. Acta Zool Fenn 108: 130 reindeer has increased over time, but polar bears are Ln O 1970) The polar bear Ursus maritimus Phipps) in the opportunistic and at least some polar bears in the Svalbard area. Nor Polarinst Skr 149: 1115 population now consider Svalbard reindeer as prey. Lowry LF, Burns JJ, Nelson RR 1987) Polar bear, Ursus mariti- Collectively, the observations suggest plasticity in for- mus, predation on belugas, Delphinapterus leucas, in the Bering and Chukchi seas. Can Field Nat 101: 141146 aging behaviour of polar bears. Madsen J, Bregnballe T, Mehlum F 1989) Study of the breeding ecology and behaviour of the Svalbard population of light- Acknowledgements This research was funded by the Norwegian bellied Brent goose Branta bernicla hrota. Polar Res 7: 121 Polar Institute. We are grateful for the use of eld observations Mehlum F 1990) Birds and mammals of Svalbard. Norwegian from J.D. Bulens, P. Bulens-van Spronsen, R. Eide, S. Onarheim, Polar Institute, Oslo N.A. ritsland and L. Aby. O.G. Stoen kindly provided us with Miller GD, Woolridge DR 1983) Small game hunting behaviour of contacts with some people who had observed polar bear and polar bears, Ursus maritimus. Can Field Nat 97: 9394 reindeer interactions. All research conducted during this study was Norwegian Hydrographic Service 1990) Arctic Pilot: Svalbard approved by the Norwegian Animal Research Committee. and Jan Mayen, 2nd edn. Norwegian Hydrographic Service, Stavanger ritsland NA, Alendal E 1986) Bestandens strrelse og livshisto- rie. In: ritsland NA ed) Svalbardreinen og den livsgrunnlag. Population size and life history. Svalbard reindeer and their References basis of existence. Universitetsforlaget. Oslo pp 5260 Pedersen A 1945) Der Eisbar Thalarctos maritimus Phipps): ver- Belikov SE 1976) Behavioral aspects of the polar bear, Ursus breitung und lebensweise. Aktieselskabet Bruun, Copenhagen maritimus. Bear Biol Manage 3: 3740 Reimers E 1977) Population dynamics in two subpopulations of Boertje RD, Gasaway WC, Grangaard DV, Kelleyhouse DG reindeer in Svalbard. Arct Alp Res 9: 369381 1988) Predation on moose and caribou by radio-collared Russell RH 1975) The food habits of polar bears of James Bay grizzly bears in east central Alaska. Can J Zool 66: 24922499 and southwest Hudson Bay in summer and autumn. Arctic 28: Calvert W, Stirling I 1990) Interactions between polar bears and 117129 overwintering walruses in the Central Canadian High Arctic. Smith AE, Hill MRJ 1996) Polar bear, Ursus maritimus, depre- Int Conf Bear Biol Manage 8: 351356 dation of Canada goose, Branta canadensis, nests. Can Field Cole GF 1972) Grizzly bear-elk relationships in Yellowstone Nat 110: 339340 National Park. J Wildl Manage 36: 556561 Smith TG 1980) Polar bear predation of ringed and bearded seals Derocher AE, Stirling I 1996) Aspects of survival in juvenile polar in the land-fast sea ice habitat. Can J Zool 58: 22012209 bears. Can J Zool 74: 12461252 Smith TG 1985) Polar bears, Ursus maritimus, as predators of Derocher AE, Andriashek D, Stirling I 1993) Terrestrial foraging belugas, Delphinapterus leucas. Can Field-Nat 99: 7175 by polar bears during the ice-free period in western Hudson Smith TG, Sjare B 1990) Predation of belugas and narwhals by Bay. Arctic 46: 251254 polar bears in nearshore areas of the Canadian High Arctic. Donaldson GM, Chapdelaine G, Andrews JD 1995) Predation of Arctic 43: 99102 thick-billed murres, Uria lomvia, at two breeding colonies by Stempniewicz L 1993) The polar bear Ursus maritimus feeding in a polar bears, Ursus maritimus, and walruses, Odobenus rosmarus. seabird colony in Frans Josef Land. Polar Res 12: 3336 Can Field Nat 109: 112114 Stirling I 1974) Midsummer observations on the behavior of wild Hakala AVK, Staaland HPE, Red KH 1986) Taxonomy and polar bears. Can J Zool 52: 11911198 history of arctic island reindeer with special reference to Stirling I, Archibald WR 1977) Aspects of predation of seals by Svalbard reindeer A preliminary report. Rangifer Spec Issue polar bears. J Fish Res Board Can 34: 11261129 1: 360 Stirling I, Derocher AE 1990) Factors aecting the evolution and Klein DR, Meldgaard M, Fancy SG 1986) Selective factors in the behavioral ecology of the modern bears. Int Conf Bear Biol determinants of leg length in Rangifer. Rangifer Spec Issue 1: Manage 8: 189204 365 Watts PD, Hansen SE 1987) Cyclic starvation as a reproductive Krog J, Wika M, Lund-Larsen T, Nordfjell J, Myrnes I 1976) strategy in the polar bear. Symp Zool Soc Lond 57: 305318 Spitsbergen reindeer, Rangifer tarandus platyrhyncus Vrolik: Young DD Jr, McCabe TR 1997) Grizzly bear predation rates on morphology, fat storage and organ weights in the late winter caribou calves in Northeastern Alaska. J Wildl Manage 61: season. Norw J Zool 24: 407417 10561066

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