Porcupine Caribou Herd Monitoring
Government of Yukon, Canadian Wildlife Service,
Alaska Department of Fish and Game and the U.S. Fish and Wildlife Service
Rationale
Female caribou, just released after being fitted with
a satellite collar.
© Martin Kienzler |
The Porcupine caribou herd is a large population of barren-ground caribou
that migrates throughout the northern Yukon, Alaska and the Northwest Territories.
In 2001 the size of the herd was estimated at 123,000 caribou. Information
about the Porcupine caribou herd is required for understanding the current
status of the herd and how it is changing. Current monitoring is important
because existing and planned developments in the range of the herd (e.g. oil
and gas development) and changes in the arctic environment may affect the size
and condition of the herd. This project is conducted by the Government of Yukon,
the Canadian Wildlife Service, the Alaska Department of Fish and Game and the
U.S. Fish and Wildlife Service. Parts of this work are conducted under the
direction of the Porcupine Caribou Herd Management Plan. Parks Canada is a
partner in this project, contributing funds and other resources towards the
project.
Objectives
- To estimate the size, age and sex composition, body condition, productivity,
over winter survival of caribou calves, adult female mortality, distribution
and movements of the Porcupine caribou herd.
Methods and Information Collected
- Surveys are conducted throughout the range of the herd in northern Alaska,
Yukon and the Northwest Territories.
- A photocensus of the Porcupine caribou herd is attempted every 3 years
while the herd is congregated on their post-calving grounds.
- Composition counts are conducted every year in March to determine the calf:cow
ratio.
- A calving survey is conducted by locating satellite and radio collared
caribou starting in late May. Cows are located daily until they give birth
and then located again in approximately 1 week to document perinatal calf
mortality. Another survey is done in late June or early July to calculate
calf survival rates to 1 month of age. Calf survival to 9 months of age is
documented during the March composition count.
- Adult female mortality rates are estimated from death rates of satellite
radio collared female caribou. The U.S. Fish and Wildlife Service started
a new adult female mortality study in October 2003. This mortality study was
conducted throughout the winter of 2003-04.
- Satellite collars are used to determine the seasonal distribution and movements
of the herd.
Results
- The last photocensus was conducted in 2001. This photocensus estimated
123,000 caribou in the herd.
- The March composition count for 2003 showed about 38 calves for every
100 cows. This is slightly higher than in recent years and higher than the
10-year average. However, because the calf:cow ratio was lower from 1994 to
1999, it is feared that the current levels of reproduction are not enough
to stop the decline in herd size that has occurred since 1989.
- The 2003 calving survey showed that the birth rate for the herd this year
was 87%, determined from the 61 of 70 radio-collared adult cows that were
observed to be pregnant or accompanied by a calf in early June. At the end
of June, post calving survival was found to be 85%, which represents a calf:cow
ratio of 69%. Birth rate and post-calving survival of calves in 2003 were
identical to rates from 2002. The late June calf:cow ratio was the highest
since 1999.
Years of Data
- Population estimates have been conducted since 1972.
Calf mortality, calf:cow ratios and birth rate have been collected
since 1983.
- Seasonal range use has been documented since 1970.
Partners
- Alaska Department of Fish and Game (project lead)
- U.S. Fish and Wildlife Service (project lead)
- Government of Yukon (project lead)
- Canadian Wildlife Service (project lead)
- Government of the Northwest Territories
Funding
- Alaska Department of Fish and Game
- U.S. Fish and Wildlife Service
- Government of Yukon
- Canadian Wildlife Service
- Government of the Northwest Territories
- Parks Canada
Data Location
- Alaska Department of Fish and Game
- U.S. Fish and Wildlife Service
- Government of Yukon
- Canadian Wildlife Service
Contacts
Dorothy Cooley
Regional Biologist
Department of Environment
Government of Yukon
P.O. Box 600 (R-5R)
Dawson City, YK Y0B 1G0
Phone: (867) 993-6461
Fax: (867) 993-6548
Dorothy.Cooley@gov.yk.ca
Ian McDonald
Conservation Biologist
Parks Canada
P.O. Box 1840
Inuvik, NT X0E 0T0
Phone: (867) 777-8807
Fax: (867) 777-8820
Ian.McDonald@pc.gc.ca