ADF&G Survey Tracks Moose and Caribou Calf Survival Rates
By ALLISON MOLLENKAMP • JUN 8, 2017
ADF&G in Dillingham tracked moose and caribou calves around the area 17 game management units. Biologists say 60% of the original moose calves are gone, many likely taken by predators.
Alaska Moose
Alaska Moose
Fish and Game's Dillingham wildlife biologist Neil Barten has been flying extensive surveys over the past few weeks to check the birth and survival rates of moose and caribou. Tracking down his collared animals around western Bristol Bay, Barten estimates only forty percent of the moose calves studied survived this “predator heavy system.” KDLG’s Allison Mollenkamp spoke with him for more details.
Neil Barten knows a lot about moose. He and his colleagues spent the spring tracking them, along with the area caribou population. They put radio collars on 35 moose cows and a total of 60 caribou calves. They were then able to track the radio signals from a plane.
Barten says the survey was initially fueled by concern for the moose population.
“In the last couple of years our twinning survey data indicated there was a lot of female moose that were not with calves at a time when I was expecting them to have calves. So I was like ‘What’s going on with that?’ And then last fall we did a composition survey in late November early December and we didn’t see as many calves with the adult moose as we had hoped to.”
What they found this time was more hopeful. Of the 35 moose they tracked, thirty-four 34 were pregnant and they eventually saw 31 with calves. Seventy percent of the cows had twins. Barten and his colleagues were surprised by the distance covered by some of the cows.
“Some of the cows move 60, 70 miles to get to where they had a calf. I mean, they just up and move. And, you know, twenty-four hours after they move they’d have calves, which is pretty cool. You know most of the cows didn’t move that far. We even had them, we had some stay completely put, had calves where they’d been all spring. But most of them moved some distance.”
Once the calves are born they can often be seen with their mothers from the plane. However, not all survive. Barten estimates that about 60 percent of the calves they saw are gone. For the moose it’s difficult to know what happened to the calves. For the caribou it’s easier because the calves themselves are wearing the radio collars. The collars signal when a calf hasn’t moved in a while.
“If this one’s giving out a mortality signal we get there with a helicopter and we look to see if it was a bear, a wolf, or an eagle, or a wolverine or what have you. Most of the mortality we detected was between brown bears, wolves, and some golden eagles as best we could determine.”
Dillingham, Alaska(red dot)
Dillingham, Alaska(red dot)
Barten says there are radio collars available with on-board cameras that could help determine the cause of death. Those collars, however, are more expensive. ADF&G will continue to track the moose and caribou for several more months.
-----------------------------------------------------------
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwjZotSK57bUAhWIMyYKHfozAlUQFggkMAA&url=http%3A%2F%2Fwww.bioone.org%2Fdoi%2Fabs%2F10.2981%2F09-014&usg=AFQjCNHbvtem1ZBCczxOkHMhuHGHgNNtsQ&sig2=ovbU7XJUzju6ct8dIGW2xQCharacteristics and dynamics of a regional moose Alces alces population in the northeastern United States
Received: February 9, 2009
Abstract
Abundance indices suggested that the moose Alces alces population in northern New Hampshire was stable despite favourable habitat and conservative harvest. Causes and rates of mortality were unknown because moose reproduction and survival was unstudied in the region. Our study was designed to investigate the dynamics of the regional population in 2002-2005. A total of 92 moose (33 cows and 59 calves) were captured and fitted with radio-collars (VHF = 83, GPS = 9). Parturition ranged from 8 May to 13 July (median = 19 May) with 78% of births occurring during 13-27 May
Moose and Calf in Alaska
Calving rate of yearlings and adults (> 2 years old) averaged 30 and 85%, respectively; twinning rate was 11%. Analysis of reproductive data from harvested cows (1988-2004) indicated that the average weight of adult cows increased but their corpora lutea count declined from ∼ 1.4 to 1.2/cow. Both ovulation rate and average weight of yearling cows declined about 25 and 4%, respectively.
Moose and Calf in Alaska
Calving rate of yearlings and adults (> 2 years old) averaged 30 and 85%, respectively; twinning rate was 11%. Analysis of reproductive data from harvested cows (1988-2004) indicated that the average weight of adult cows increased but their corpora lutea count declined from ∼ 1.4 to 1.2/cow. Both ovulation rate and average weight of yearling cows declined about 25 and 4%, respectively.
There were 39 mortalities (49% calves) with winterkill/parasite (41%), vehicle collision (26%) and hunting (18%) as the leading causes. Major sources of mortality of radio-marked cows were human-related; survival was 0.87. Annual calf survival was 0.45. Unmarked calf (0-2 months of age) survival was 0.71 with 76% of mortality in the first month of life. Radio-marked calves (∼ 7-12 months of age) had a survival rate of 0.67; 74% of the mortality was winterkill/parasite related.
Calf mortality was concentrated (88%) in late winter-early spring. The unseasonably warm and snowless fall in 2001 probably favoured high tick transmission and increased tick loads on moose that resulted in high calf mortality (0.51) and measurable cow mortality (10%) in mild winter-spring 2002. Documentation of substantial tick-related mortality of radio-marked moose calves was unique to this study. The stability of the moose population probably reflects the variation in annual recruitment and lower fecundity of yearling cows associated with heavy infestations and epizootics of winter tick. Given that fertility, calving rate and body condition of adult cows, and summer calf survival are annually high, the population should recover from tick epizootics that periodically inhibit population growth.
---------------------------------------------------------------------------------
TEMPORAL PATTERNS IN THE SURVIVAL OF TWIN AND SINGLE MOOSE (ALCES ALCES) CALVES IN SOUTHCENTRAL ALASKA
American Society of Mammalogists
Accepted: March 20, 1999
No comments:
Post a Comment