Helicopter wolf control helps caribou calves
Survival rate soars after shooters thin a herd’s predators.
By Craig Medred, Anchorage Daily News, November 11th, 2008 [here]
[Humane and science-based culling of] wolves on the Alaska Peninsula appears to have had the desired effect — more caribou got a chance to live, according to biologists with the Alaska Department of Fish and Game.
As ugly and as politically incorrect as the wolf killing might seem to some [such as urbanites who have zero wildlife management experience], they said, the helicopter [culling] that took place earlier this year saved caribou, especially young caribou, from being eaten alive.
Fall surveys of the Southern Alaska Peninsula caribou herd completed in October found an average of 39 calves per 100 cows. That’s a dramatic improvement from fall counts of only 1 calf per 100 cows in 2006 and 2007.
The success of past wolf-control programs, and of some of those still under way elsewhere in the state, has varied significantly, depending on what predators were involved [no facts given to support this statement]. In some cases, bears, eagles and climate have proved to have more influence on calf survival than wolves [no facts given to support this statement, either, especially the climate part].
In this case, however, even some groups staunchly opposed to Alaska wolf-control efforts are conceding the removal of 28 wolves appears to have played a major role in caribou calf survival. …
The southern peninsula caribou has been in a free fall for several years.
Numbering almost 5,000 animals at the start of this decade, the southern herd had shrunk to about 600 caribou by last year. A joint state-federal management plans calls for maintaining a herd of 3,000 to 3,500 animals to provide for local subsistence needs and the general productivity of the ecosystem.
Researchers studying the caribou decline concluded that the range the caribou use in and around the Izembek National Wildlife Refuge has plenty of food, and the few bull caribou shot by hunters prior to a prohibition on all hunting last year weren’t an issue.
What was fueling the decline, researchers said, was the high ratio of predators — bears and wolves — to prey in the area. The predators were killing and eating caribou faster than the animals could reproduce, leaving the population nowhere to go but down.
Caribou populations need 20 to 25 percent of calves to survive each year just to sustain herd size, given significant annual losses to accidents, starvation and predation even in the best of times.
If calf survival falls below that, the herd begins to shrink, and the shrinkage accelerates as the population becomes increasingly dominated by older animals nearing the natural ends of their lives.
In some cases, research indicates, the only way to keep the population from falling to very low numbers and getting trapped in what biologists call a “predator pit” is to reduce the number of predators. … [more]