ADFG Announces Another Round Of Predator Eradication To Help Sustain Mulchatna Caribou

The following is courtesy of the Alaska Department of Fish and Game:

As part of a two-year plan to help sustain Mulchatna Herd caribou, 81 bears have been killed in the area over the the past year. (LISA HUPP/USFWS)

ADF&G concludes predator control for the second year to benefit Mulchatna Caribou

(Dillingham) – In March 2023 the Alaska Board of Game approved and directed the department to implement a revised Intensive Management Program to increase abundance of the Mulchatna caribou herd (MCH), which has been closed to hunting since fall 2021. This herd peaked at approximately 200,000 animals in 1997 and by 2019 it declined to just over 13,000 animals (~94% decline). It remains at this lower level of abundance today. During the peak, this herd provided up to 4,770 caribou for local communities, and resident and nonresident hunters. Recognizing that there are 48 communities within the traditional range of this once expansive herd, the public requested that the department and board work to rebuild the herd and restore this source of food.

Caribou survival can be affected by disease, predation, harvest, and food availability and quality. The Board of Game reasoned that addressing predation is something that can be addressed. Wolf control by the public, using aerial methods authorized by the Board of Game, has been active during winter since 2012. While approved areas for wolf control have expanded, the herd size decreased to its current low level and calf summer survival has been poor. Both bears and wolves have been identified by research as important factors causing low calf survival and potentially limiting the ability of the herd to increase. The board revised the existing wolf control program to include bears and wolves specifically on the caribou calving grounds. Reducing the number of bears and wolves was a logical step in adaptive management to determine if summer calf survival can be improved. While there are other factors to consider with the herds’ decline (e.g., habitat capability, disease), predator control is an immediate tool the department can use to attempt to reverse the herds’ decline.

This control program is specifically designed as an effort to enhance calf survival. The objective was to quickly and humanely remove predators within an area defined as the calving grounds of the western subgroup during the calving season. The spring portion of this intensive management effort was accomplished by department staff and the program has not expanded outside the western calving ground. Predator reduction activities were completed on state land only and efforts in 2024 were focused on an area about half the size of the 2023 operational area (approximately 530 mi2). No animals were removed from Wood-Tikchik State Park.

Staff spent 4 days in April searching for wolves in the removal area and 21 days between May 10 and June 5 following caribou and searching for evidence of predation (i.e., caribou fleeing, predators actively chasing or eating caribou). All bears and wolves located in this search were killed and hides and skulls were salvaged when safe to do so. A total of 81 brown bears and 14 wolves have been removed this year and the program concluded for the year on June 5.

The Division of Wildlife Conservation (DWC) will continue to monitor calf survival through the first year of life. Radio collars will be used to determine if calf survival increased in the treatment area as intended. DWC will be monitoring post-calving aggregations for signs of increased abundance this year compared to recent years and will compare these data to the untreated eastern Mulchatna calving groups. This information, along with information derived from ongoing caribou nutritional research and disease monitoring, will be evaluated to determine if further bear and wolf reductions during spring calving are warranted to further improve calf survival and herd growth. During the first year of the program in 2023, we documented an increase in calf survival through the fall which was indicated by an increase in the calf-to-cow ratio of 44 calves per 100 cows within the West MCH, which is well above the 10-year average of 23:100. A 2024 photocensus will be conducted as soon as the caribou aggregate on their summer range and conditions allow. In addition, fall composition surveys will be conducted in October.

The department has no population concerns for either bears or wolves. Bear and wolf populations are healthy in western Alaska. The removals of wolves and bears in the western spring calving control area are occurring in a relatively small area that is surrounded by intact habitat on state and federal lands where control activities are not occurring. Those areas serve as refugia from the spring control activities for predator populations. Based on prior research, once reduction activities have been completed a full recovery to pretreatment levels are expected to occur within a few years from a combination of predator immigration into the area and reproduction.