Re: Moose/Caribou dilemma?
That would be my guess also. Moose are so large that if you don't get them gutted and skinned, they can spoil overnight in the field. They're much bigger than caribou, and if the meat isn't cooled off quickly, they bone sour. In addition to that issue, a big bull moose is equal to about 7-8 round trips of hauling meat and antlers by backpack. A caribou is about 3-4 round trips for a backpack hunter.
Another possibility is that any subsistence hunter would prefer to harvest their game so that they animals can be transported by 4-wheeler, boat, or snow machine. And caribou and caribou seasons are probably more accommodating that way also.