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Diet of Terrestrial Tundra Vertebrates

Regional differences in the abundance and availability of various prey would

mean that polar bear diets would differ across broad geographic regions. Polar bears

forage over thousands of kilometers and they do not defend individual territories. Polarbears are known to eat ringed seal, bearded seal, harbor seal, harp seal, hooded seal,

walrus, beluga whale, and narwhal. Regional differences among polar bears plays a

significant role in a polar bear’s diet. lso the demographic differences also affect the

diet of a polar bear. !easonal differences also play a role in polar bear diets, in both

"ancaster !ound and #af$n #ay, beluga whale tended to contribute more to polar bear

diets in spring%summer than fall%winter. Despite the lack of a multivariate seasonal

effect in Davis !trait, consumption of harp seal was higher in spring%summer than in

fall%winter, especially among female bears. Polar bears in the &ulf of #oothia consumed

signi$cantly more beluga whale in spring%summer and more ringed seal in fall%winter,

whereas bears in 'o(e #asin consumed the most harbor seal in fall%winter )Thiemann,

*++-.

The effects of global climate change are currently being e(pressed in the rctic.

 lready documented are warming temperatures, melting glaciers, reduction of pack icee(tent, shrinking lakes, and alteration of vegetative communities. n terms of arctic

vegetation specifically, lichen abundance is predicted to decline while vascular shrubs

and graminoids )grasses and sedges- may increase. Though /aribou gra0ing and

trampling have been implicated as ma1or factors in reduced lichen abundance, climate

change may further e(acerbate declines. /aribous are found to eat "ichens,

&raminoids, 2oss, !hrubs and 'orbs )3oly, *++4-.

The arctic fo( is one of the most characteristic species of the tundra. The arcticfo( is among the smallest species in the dog family, normally weighing between *.5 and

6.+ kg. rctic fo(es have a circumpolar distribution and are found in all kinds of tundra

habitats. "emmings, small rodents, hares, birds, eggs, fish, and carrions constitute the

main food source for arctic fo(es )'uglei, *++-.

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Throughout their breeding range snowy owls have a narrow, speciali0ed diet

almost entirely made of small mammals during summer. 'or that reason, it has long

been thought that snowy owls were moving to southern areas to prey upon similar prey

type during the winter. They all found that small mammals or rodents comprised the bulk

of the food consumed by these birds )Therrien, *+77-.

Rock Ptarmigan were more common in meadows with graminoids and scattered

woody shrubs. 8illow Ptarmigan are socially dominant over Rock Ptarmigan in areas of

sympatry, but the latter avoid dense shrubs during breeding and this may lower

competition. Rock Ptarmigan territories were more often in lower alpine meadows at

intermediate elevations, with a ground cover of graminoids interspersed with rock,

woody shrubs and heather. 8ith this abundance of food resource around it, the rock

ptarmigan consumes leaves, flowers, berries and buds, also the young also feeds on

insects )8ilson, *++-.

#ibliography

• 'uglei, 9., : ms, R. . )*++-. &lobal warming and effects on the arctic

fo(.Science progress, 91)*-, 745;74>.

• Therrien, 3. '., &authier, &., : #?ty, 3. )*+77-. n avian terrestrial predator of the

 rctic relies on the marine ecosystem during winter. Journal of Avian

Biology , 2 )6-, >@>;>@