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Three Mexican wolf pups successfully cross-fostered into pack in Arizona

Posted September 14, 2020

Cross fostering supports genetic diversity in endangered Mexican wolves


PINETOP, Ariz. — On Aug. 24, Arizona Game and Fish Department (AZGFD) wolf biologists using remote trail cameras documented eight Mexican wolf pups, an endangered subspecies, in the Hoodoo Pack in the northeastern Apache Sitgreaves National Forest. In April, AZGFD and the U.S. Fish and Wildlife Service (USFWS) cross-fostered four genetically valuable wolf pups into the Hoodoo Pack from a litter in captivity at the Sedgwick Zoo in Wichita, Kansas.

After cross-fostering was completed by AZGFD and USFWS, there were five wild Mexican wolf pups and four cross-fostered pups for a total litter of nine pups in this Hoodoo Pack litter. At least three of the pups observed are cross-fostered. Biologists are working to determine if a fourth pup may also be a cross-fostering success.

AZGFD wolf biologists will begin fall trapping efforts in September to document cross-fostered wolves that have survived and to deploy tracking collars to monitor and manage the wolf population in Arizona.

Cross-fostering is a proven method used by the Mexican Wolf Interagency Field Team (IFT) to increase genetic diversity in the wild Mexican wolf population. It involves placing genetically diverse pups less than 14 days old from captive breeding populations into wild dens with similarly aged pups to be raised as wild wolves. The IFT has documented that cross-fostered pups have the same survival rate as wild-born pups in their first year of life (~50%), and survival rates using this technique are generally higher than other wolf release methods. Furthermore, cross-fostered pups raised in wild packs are less likely to get into conflicts with humans than pups raised in captivity.

This spring, biologists from the AZGFD, New Mexico Department of Game and Fish and Mexican Wolf Species Survival Plan, with extensive logistical support from USFWS, cross-fostered a total of 20 genetically diverse wolf pups from captive facilities across the United States into litters of wild wolf packs. Since 2014, there have been 52 genetically diverse wolf pups cross-fostered into the wild to work toward genetic recovery of the Mexican wolf population.