I was reading a paper on the decline of some AK caribou herds most of this pertains to the Southern Alaska Peninsula herd but sounds like the bios think the problems could be widespread.
The first thing they say is that calf recruitment is low.. as low as 1 calf per hundred cows!! The bios said for the herd to grow they needed more than 25 calves per 100 cows. They figured they had about an 80% pregnacy rate but wanted 95%.
The thing I found interesting was nowhere in the paper could I find why they thought calf/ratio was so low. Pregnancy rates of 80% would no doubt be enough to grow the herd but only if those calves survived.
I have never been there but if what I have read is true and calf survival is that low it doesnt take 25 studies and hundreds of thousands of dollars to figure out the problem is whatever is killing the calves!
I know we were talking about moose populations on another thread where Bushrat said ratios of 12/100 were normal and the population would stay stable, but apparently the Bios think caribou need more than 25/100 for the herd to grow.
I know you that live in AK already knew about this herd and the problems it faced, but I didnt. And I found it beyond belief at least in the info I could find they didnt try to address the reason calf recruitment was so low.
Hope this area is one that is getting the predator control!