Contents:
Calving Update 2004
How many of the satellite collared cows had calves?
Maps and data provided by Steve Arthur, ADF&G
Calving Update 2004
Caribou began moving towards the calving grounds from their winter ranges in late April - early May 2004. Following traditional migration routes, the caribou that had wintered in the Yukon in the Ogilvie and Hart River Basins moved north between Old Crow and the Driftwood River. Those caribou that had wintered in Alaska generally moved east around the Brooks range before swinging north to the British Mountains in the Yukon. Persistent snow on the coastal plain in Alaska slowed the migration, and all of the satellite collared caribou, and most of the herd calved in the Yukon. It was thought that calving peaked between June 3rd and 4th, 2004, which is about average.
The Alaska Department of Fish and Game and the U.S. Fish and Wildlife Service conducted radio-tracking flights between June 1st and 4th. A second flight was conducted June 14th to confirm calving of those caribou that were judged to be pregnant on June 4th, but hadn't yet calved.
Click on map to enlarge
Locations of radiocollared Porcupine caribou cows,
1-4 June 2004.
|
Seventy-three radiocollared adult cows were observed during early June.
Sixty radiocollared cows (82%) were judged to be parturient
(pregnant or had given birth).
The average number of cows giving birth since 1987 is 81.5 %,
so this year was right on average.
|
Click on map to enlarge
Locations of radiocollared Porcupine caribou cows,
23 June 2004.
|
A further flight on June 23rd was attempted to estimate calf survival. By this time the caribou had moved into Alaska and had aggregated in very large, dense groups, which is somewhat early for the period of aggregation that more often occurs in early July. This would have been the optimal time to conduct the photocensus which was scheduled for this year. However, the coastal plain was enveloped in fog and smoke from interior wildfires which not only made it impossible to determine which cows were still accompanied by their calves, but also precluded a photocensus. We hope to be able to conduct a census in 2005.
|
Return to top
How many of the satellite collared cows had calves?
Of the satellite collared cows, Lynetta and Blixen can generally not be observed because of malfunctioning radio-transmitters (Note: the satellite transmitters give the general location, but the radio-transmitter is needed to actually find the animal). Both of these caribou traveled to the calving grounds and likely were pregnant. 11 other satellite collared caribou were located.
Arnaq, Catherine, Cocoa, Donner, Helen, Pingo, Rocky and Tundra were observed with calves.
Aurora was judged to have produced and lost a calf before she was first observed, and Iola and Isabella were judged not pregnant.
Below is a summary of all caribou and information on whether or not they calved the past SEVEN years.
Note: -- means that the caribou was not located
Lupine made it to the calving grounds, but died on May 21st. Biologists working in the area were able to recover her collar, but not determine cause of death.
As mentioned above, Isabella made it to the coastal plain of Yukon but did not calve. She moved into Alaska with the rest of the herd in late June, but by mid July had stopped moving. We have not been able to recover her satellite collar.
Download the memorandum by Steve Arthur of the Alaska Department of Fish and
Game
to read the entire 2004 Calving Report as a printer friendly Acrobat pdf file (295 KB)
|
