ORIGINAL PAPER

Andrew E. Derocher á éystein Wiig á Georg Bangjord

Predation of Svalbard reindeer by polar bears

Accepted: 26 March 2000

Abstract Polar bears (Ursus maritimus) are believed to

be obligate predators on marine mammals, and partic-

ularly, ontwo species of seals. This paper reports on

observations of polar bears preying (n ˆ 7) and scav-

enging (n ˆ 6) onSvalbard reindeer (Rangifer tarandus

platyrhyncus). Similar to their closest evolutionary

ancestor, the brown bear (U. arctos), polar bears are

opportunistic and will prey on ungulates. Reindeer are

likely of minor importance to the foraging ecology of

polar bears inSvalbard, but the observations suggest

behavioural plasticity in response to a novel prey item.

Introduction

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

(P. groenlandica) (Lùnù 1970; Stirling and Archibald

1977; Smith 1980). Polar bears are opportunistic, how-

ever, and commonly prey on other marine mammals

such as white whales (Delphinapterus leucas) (Smith

1985; Lowry et al. 1987), narwhal (Monodon monoceros)

(Smith and Sjare 1990) and walrus (Odobenus rosmarus)

(Calvert and Stirling 1990). Polar bears also will feed on

a wider range of species including little auks (Alle alle)

(Stempniewicz 1993), pale-bellied brent geese (Branta

bernicla hrota) (Madsenet al. 1989), Can

ada geese

(B. canadensis) (Smith and Hill 1996), thick-billed mur-

res (Uria lomvia) (Donaldson et al. 1995), willow ptar-

migan(Lagopus lagopus) (Miller and Woolridge 1983)

and vegetation (Russell 1975; Derocher et al. 1993).

The distributionof polar bears, whenonland, over-

laps with that of two large terrestrial mammals, reindeer

(Rangifer tarandus) and muskox (Ovibos moschatus).

While polar bears have beenreported to feed onreindeer

and muskox in Greenland (Pedersen 1945), there is only

one report of a polar bear killing an ungulate. A trapper

in Greenland found a dead muskoxen, still warm, that

was thought to have beenkilled by a polar bear seenin

the area (Pedersen1945).

Inthis paper, we report onobservations of predation

and scavenging of Svalbard reindeer (R. t. platyrhyncus)

by polar bears.

Materials and methods

Study area

We collected observations of seven predation events and six in-

stances of scavenging by polar bears on Svalbard reindeer between

1983 and 1999. The study was conducted in the Svalbard Archi-

pelago located inthe westernBarents Sea between74° and 81°N

and 10° and 35°E. Observations of predation and scavenging of

Svalbard reindeer were obtained during ®eld operations of a re-

search program designed to assess the population dynamics and

ecology of polar bears insoutheast Svalbard. Inaddition, obser-

vations were obtained from individuals working or travelling in

Svalbard. For observations other than those of the authors, we

have identi®ed the observers of each incident.

Results

On 1 April 1999, a polar bear was observed on land near

Ingeborgfjellet (77°40¢N, 14°E) walking into the wind

(R. Eide). The bear's head was held high, moving from

side to side as if sning the air. The bear moved out of

Polar Biol (2000) 23: 675±678

Ó Springer-Verlag 2000

A. E. Derocher (&)

NorwegianPolar Institute,

9296, Tromsù, Norway

e-mail: [e-mail]

Tel.: [phone], Fax: [phone]
é. Wiig

Zoological Museum,

University of Oslo, Sars gate 1,

0562, Oslo, Norway
G. Bangjord

Odden, 7057, Jonsvatnet, Norway

sight and, when next seen, was 5±600 m away and was

dragging a fresh reindeer carcass that left a large blood

trail. Giventhe cold temperatures during this observa-

tion, the reindeer had either died very recently or was

killed by the bear. After 2 days onthe 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.

Inthe same period that the polar bear was seenwith 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 thanhealthy

individuals.

On6 March 1998, fresh polar bear tracks, estimated

to be 6 h old, were observed near Kapp Bjùrset, Sval-

bard (77°50¢N, 13°30¢E) (J.D. Bulens and P. Bulens-van

Spronsen). The tracks led to a fresh reindeer carcass,

believed to have beenkilled 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 onanolder 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.

On14 March 1998, againat Kapp Bjùrset, following

a recent snowfall, an adult male polar bear (ca. 300 kg)

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

area of 10 m radius. The body of the reindeer was still

warm. The polar bear had just started to feed onthe

carcass whenobserved. The polar bear ¯ed the kill upon

seeing the observer and then swam in an arc into the

slush ice, landing back on shore ca. 60 m from where it

entered the water. It sni€ed the air and watched the

observer. It then moved further onto land and started to

run. Approximately 20 m in front of the bear, a snow-

covered reindeer jumped up and ran away. The bear

continued running until it stopped with forelegs sti€

and stood quietly over another reindeer, a 10-month-old

calf, which was almost totally snow covered. Details of

how the reindeer was killed were not observed. After less

than a minute, the bear carried the calf by the neck for

a distance of about 200 m (Fig. 1). The bear fed on

the carcass but retreated to the sea againwhendisturbed

and did not return to feed on it. However, the bear

was observed 4 h later feeding on the ®rst adult male

reindeer with which it had been observed. Several

other freshly killed reindeer were observed in the same

area later inMarch and April 1998, after the above

observations.

On 9 April 1997, while conducting ®eld ecology

studies of polar bears inSvalbard, a fresh set of polar

bear tracks was observed and followed for approxi-

mately 5 km to Delitschùya (77°23¢N, 22°31¢W), which

lies a few hundred meters from the larger Edgeùya.

A kill site of anadult reindeer was observed from the

air. Anadult female polar bear (15 years old) and two

yearling cubs were captured at the site. From recon-

structionof the tracks inthe area, the female

approached the island directly across the ¯at, land-fast

sea ice. She may have smelled the reindeer bedded on the

edge of Delitschùya approximately 10 m from the sea

ice. The female circled behind the reindeer, approached

from the top of the island, and captured the reindeer

while it was lying. The carcass was partially consumed

but still unfrozen when examined. The bears had a

bedding area about 10 m from the carcass.

InMarch/April 1996, tracks of a polar bear were seen

that suggested a successful predationevent inColesdalen

(78°N, 15°E) (L. AÊby). It appeared that the polar bear

slowly approached downhill towards a reindeer that was

lying in a shallow snow bed. It appeared that the bear

made a short dash at the reindeer and killed it with

minimal struggle.

Inlate March 1995, inthe pass betweenRingdalen

and Tufsdalen (78°03¢N, 15°44¢E) at 500±600 m above

sea level and about 20 km from the coast, tracks were

observed of a polar bear travelling northward through

40±50 cm of fresh snow (S. Onarheim). The tracks led

directly to a dead reindeer carcass that was still warm

and about half consumed by a polar bear estimated at

2±3 years of age. Signs indicated no struggle. The feed-

ing area covering a 10 m ´ 10 m area. It was thought

that the polar bear killed the reindeer while it was

sleeping.

Inmid-March 1992, a polar bear was observed eating

a reindeer at DuneÂrbukta, (78°10¢N, 19°E), about 600 m

from shore at 100 m above sea level (S. Onarheim). The

bear was present at the site for at least a day based on

recent weather patterns. The bear had a sleeping pit and

eating area at the site but recent snow had obscured all

Fig. 1 Adult male polar bear with freshly killed 10-month-old

reindeer, Kapp Bjùrset, Svalbard (photograph, G. Bangjord)

676

tracks. Most of the reindeer had been eaten but lack of

freezing suggested the reindeer had died recently or was

killed. Other reindeer were present in the area during

both sightings.

Polar bears have been frequently observed scavenging

reindeer. On 17 September 1998, an adult female

(13 years old) believed to be pregnant was captured near

the carcass of a dead reindeer on Firneheia, Edgeùya,

10 km from the coast. Fragments of ¯esh and hair be-

tweenthe female's teeth indicated that she had been

feeding on the reindeer. In this instance, a female with

two 9-month-old cubs and another single bear were

observed near the carcass. On 8 April 1997, an adult

female (11 years old) with two cubs-of-the-year (ca.

4 months old) were located at a maternity den site on

Edgeùya feeding on a reindeer carcass just outside the

den. The following day, an adult female (7 years old)

and two cubs-of-the-year were found on land on Edge-

ùya feeding on another reindeer carcass. In the same

area, a bear was tracked from the sea ice onto land

where the bear dug a reindeer carcass from the snow and

fed onit. InApril 1983, two di€erent polar bears were

observed on Edgeùya coming o€ the sea ice and scav-

enging reindeer carcasses (N. A. éritsland). In one case,

the bear returned to the sea ice with the carcass.

Discussion

Polar bears of both sexes and all age classes are common

near shore in Svalbard and frequently cross over land

moving between fjords (A.E. Derocher and é. Wiig,

unpublished data). Svalbard reindeer are distributed

throughout the Svalbard Archipelago with a total pop-

ulation size of ca. 11,000 (éritsland and Alendal 1986).

Approximately 60% of Svalbard is covered by glaciers

and most of the vegetation is found from the tidal zone

to 200 m above sea level (Mehlum 1990). Therefore,

Svalbard reindeer are often located near shore or in

valleys where they are more likely to encounter polar

bears.

The Svalbard reindeer have been isolated on Svalbard

for ca. 20,000±40,000 years (Hakala et al. 1986). There

are no wolves (Canis lupus) or indigenous humans in

Svalbard and Svalbard reindeer have evolved with little

or no predation. Svalbard reindeer were frequently ob-

served to approach polar bears and may not consider

them as predators. Absence of common terrestrial pre-

dators may have reduced vigilance behaviour and

increased vulnerability to occasional predation by polar

bears.

Body size and energetics were postulated as signi®-

cant factors governing how bears of di€erent body size

hunt ungulates (Stirling and Derocher 1990). In partic-

ular, larger bears hunt by stalking close to their prey and

thenmake a short rush, while smaller bears may be able

to sustain longer chases (Stirling and Derocher 1990).

While the running speed of polar bears is undocu-

mented, we have estimated (A.E. Derocher and é. Wiig,

personal observation) from ®eld studies during capture

procedures, a top speed near 30±40 km/h. The Svalbard

reindeer is a recognized sub-species characterized by

short legs, thick fur and the ability to store large

amounts of fat (Krog et al. 1976). Leg length in reindeer

relates to nutritional stress, energetic eciency of for-

aging through snow of varying depths, eciency of

locomotion, and ¯eetness in relation to predator

avoidance (Klein et al. 1986). Svalbard reindeer can

reach speeds up to 60 km/h on a good running surface,

but under deep snow conditions, cannot exceed speeds

of about 20 km/h (N.A. éritsland, personal communi-

cation). Precipitation in Svalbard is typically less than

400 mm per year (NorwegianHydrographic Service

1990) and strong winds keep the snow thin in most

near-shore areas. The dearth of observations of polar

bears chasing reindeer is consistent with the ability of

Svalbard reindeer, usually, to easily escape when aware

of the bear.

The Svalbard reindeer population is likely regulated

by adverse climatic conditions that restrict access to

food during the winter/spring (Reimers 1977). All in-

stances of polar bear predation on reindeer occurred

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

cubs emerging from dens in March/May have undergone

an extended winter fast and food resources are critical

for cub survival (Watts and Hansen 1987; Derocher and

Stirling 1996). Therefore, reindeer carcasses may present

animportant food source for some mothers.

Polar bears oftenhunt seals by stalking quietly close

to a seal lying on the snow or up to a ringed seal in a lair,

using vision and scent to locate the prey, and subse-

quently make a short dash or pounce into snow covering

the lair (Stirling 1974). The hunting of reindeer was

similar to methods polar bears use on seals. All instances

of predation occurred on reindeer that were lying in

snow-covered areas, and in at least one case, the reindeer

was snow covered. During snow-free times of the year,

polar bears are more visible, resulting in greater di-

culty in stalking reindeer. Polar bears are thought to

have evolved from brownbears (U. arctos) (KurteÂn

1964), which canprey onreindeer and caribou, moose

(Alces alces) and elk (Cervus elaphus) (Cole 1972; Boertje

et al. 1988; Young and McCabe 1997). Adult Svalbard

reindeer weigh between 41 and 57 kg (Krog et al. 1976),

similar insize to adult ringed seals, but are small prey

relative to other ungulates. Lack of struggle at the ob-

served killed sites suggests that reindeer are easily killed

if captured by polar bears.

On Wrangel Island, Russia, it was reported that polar

bears were only able to catch sick reindeer incapable of

running (Belikov 1976). Lùnù (1970) stated that while

polar bears and reindeer in Svalbard often meet, he

and winter trappers in Svalbard found no evidence of

polar bears killing reindeer. We cannot determine if the

677

incidence of polar bear predation and scavenging on

reindeer has increased over time, but polar bears are

opportunistic and at least some polar bears in the

population now consider Svalbard reindeer as prey.

Collectively, the observations suggest plasticity in for-

aging behaviour of polar bears.

Acknowledgements This research was funded by the Norwegian

Polar Institute. We are grateful for the use of ®eld observations

from J.D. Bulens, P. Bulens-van Spronsen, R. Eide, S. Onarheim,

N.A. éritsland and L. AÊby. O.G. Stoenkindly provided us with

contacts with some people who had observed polar bear and

reindeer interactions. All research conducted during this study was

approved by the NorwegianAnimal Research Committee.

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