Effects of recent climate warming on caribou habitat and calf survival

By: , and 
Edited by: Rhys E. GreenMike HarleyMark Spalding, and Christoph Zöckler


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Migratory Barren-Ground Caribou Rangifer tarandus granti are the most important subsistence resource for northern indigenous peoples. They are likely to respond to global climatic changes that affect the distribution of their forage resources and the availability of forage through the year. The Porcupine Caribou herd is a large, internationally migratory herd of about 128,000 individuals that occupies the Alaska-Canada borderlands and uses a 300,000 km 2 annual range. The calving ground is a traditionally-used portion of the annual range that comprises 23,000 km2 at approximately 70° north. Caribou migrate several hundred kilometres from winter ranges to the calving ground, arriving in mid- to late-May each year. Calves are born during the first week of June, and cows and calves remain on the calving ground for 4-6 weeks before dispersing to late-summer, fall, and winter ranges.

We measured the relative amount of green vegetation using data from polar orbiting satellites (Figure 1) to assess decade-long temporal trends in large scale habitat conditions on the calving ground and to investigate Caribou response to this habitat change. The vegetation index has shown a tendency toward earlier greening in spring and later plant senescence (dying off) in much of the northern hemisphere the 1980s, concurrent with independent estimates of climate change. High density calving was consistently located where the daily rate of increase in the amount of green plant biomass during lactation was greatest, in the period 1985-1996. This was probably because of the lactating cows' need for highly digestible new plant growth. Nutritional requirements of lactating cows are about double those during the remainder of the year.

Study Area

Publication type Book chapter
Publication Subtype Book Chapter
Title Effects of recent climate warming on caribou habitat and calf survival
Year Published 2001
Language English
Publisher Royal Society for the Protection of Birds
Publisher location Cambridge, UK
Contributing office(s) Alaska Science Center
Description 3 p.
Larger Work Type Book
Larger Work Subtype Monograph
Larger Work Title Impacts of climate change on wildlife
First page 17
Last page 19
Country Canada, United States
State Alaska, Yukon Territory
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