Wide ranging an nomadic species like Peary caribou, barren-ground caribou, polar bears, grizzly bears, arctic fox, and snowy owls move in and out of Parks, so the ecological integrity of these protected areas depends on maintaining adequate habitats beyond their boundaries.
However, some populations of these species have declined over the past decades apparently as a result of changing weather patterns, and their effects on habitats. Ground icing following rain or winter thaws seems to have severely reduced caribous’ access to food on many islands. Reduced duration of winter sea ice has reduced the foraging season for polar bears. In contrast, arctic geese are faring well, apparently because of improved survival on wintering grounds. While these patterns have been documented, potential changes to the winter environment faced by the most species rich part of the arctic food web, that built on the lemmings, have not been well studied.
The Arctic Food Web
Lemmings and voles are key prey for a rich variety of predators, including arctic and red foxes, rough-legged hawks, peregrine falcons, snowy and short-eared owls, long-tailed and pomarine jaegers, glaucous gulls, weasels, wolverines, and even grizzly bears. When lemmings are scarce, these predators rely more heavily on other prey such as shorebirds, passerines, geese and arctic ground squirrels. It is hypothesized that lemming abundance and productivity depend heavily on winter snow conditions. Freezing temperatures after autumn rain and winter thaws could entomb much of the lemmings’ food in ice; insufficient snow depth means that they have to spend extra energy on basic living with too little left over for breeding. Because lemmings are so central to the dynamics of so many arctic tundra species, we need to understand how changing winter conditions may be affecting their populations.
Dr. Don Reid, WCS Canada’s Yukon –based biologist, is an organizational member of a large International Polar Year project called Arctic Wildlife Observatories Linking Vulnerable EcoSystems (ArcticWOLVES).
This project comprises a network of Canadian researchers working together to develop a network of circumpolar wildlife observatories to assess the current state of arctic terrestrial food webs over a large geographical range. A primary goal of the network is to determine the relative importance of bottom-up (resources) and top-down (predators) forces in structuring arctic food webs, and how climate affects these trophic linkages.
Arctic WOLVES will also provide baseline information to evaluate current and future population trends for a large number of species at several locations using standard protocols.
The project focuses on trophic interactions (plants-herbivores-predators) among birds and mammals of the tundra, primarily in the small to medium size range. The aim is to study the strength of these interactions and how they vary locally (i.e. across habitats) and regionally (i.e. across distant sites) in the Arctic. The working hypothesis is that top-down processes driven by predators are the primary forces structuring arctic communities. The project is comprised of sub-components based on taxonomic groups and trophic levels, for which we will quantify abundance, rates of flow between trophic levels, and dynamics. These are: plants; small mammals; ground squirrels; geese; shorebirds; ptarmigan; mammalian and avian predators; weather and snow conditions.
The field work for this project in Canada is being conductedat 6 primary sites:
- La Pérouse Bay (Wapusk National Park, MB);
- Komakuk Beach (Ivvavik National Park, YT);
- Herschel Island (Qikiqtaruk territorial Park, YT);
- Walker Bay (Kent Peninsula, NU); Bylot Island (Sirmilik National Park, NU):
- Alert (NU)
- Gilles Gauthier (U. Laval); Dominique Berteaux (UQaR); Charles Krebs (UBC) Doug Morris (Lakehead U); Bob Jefferies (UofT); Joel Bety (UQaR); Ken Abraham (UofT); Guy Morrison (CWS); Don Reid (Wildlife Conservation Society Canada); Suzanne Carriere (NWT Gov’t); Scott Gilbert (Yukon College).
- Linked to other IPY projects through 40 researchers from 9 countries (Canada, USA, Denmark, Norway, Sweden, Netherlands, Finland, Germany, and Russia).