Mexican Wolf conservation efforts continue to make major steps towards recovery of this endangered sub-species. Biologists from AZGFD continue to play an integral role on the Mexican Wolf Interagency Field Team (IFT), which also includes support from New Mexico Department of Game and Fish, White Mountain Apache Tribe, the U.S. Fish and Wildlife Service (USFWS), and others. In 2020, the IFT cross-fostered 20 genetically-valuable Mexican Wolf pups into wild wolf dens in Arizona and New Mexico in 2020.
Cross-fostering is an important process to safely reintroduce wolves in the wild. The process includes placing captive born wolf pups less than 14 days of age into wild wolf dens with pups of similar age. By minimizing human scent during transfer, the wild and fostered pups smell alike and the wild adult wolves accept and raise the fostered pups as their own. The advantage of cross-fostering verses releasing captive-bred adult wolves is that cross-fostered pups are raised wild, greatly increasing their chance of survival compared with naïve adult wolves raised around humans. Adult wolves reared in captivity are also more likely to get into conflict with humans than wild wolves. The IFT has documented that cross-fostered pups have similar survival rate as wild-born pups in their first year of life (about 50 percent).
Over a six-week period in April and May, 2020, 12 pups were fostered into four different packs in eastern Arizona. Eight others were fostered into three packs in western New Mexico. The 20 pups came from Mexican Wolf captive breeding facilities including the Endangered Wolf Center in Missouri, Sedgwick County Zoo in Kansas, Sevilleta National Wildlife Refuge in New Mexico, the California Wolf Center, and the Phoenix Zoo in Arizona. Aerial support of three cross-foster operations was provided by LightHawk Conservation Flying. A private jet donor made possible one transfer of pups from the Endangered Wolf Center to Arizona.
The IFT has successfully used cross-fostering since 2014 to boost the genetic diversity of the wolf population of Mexican Wolves in Arizona and New Mexico. Cross-fostering of Mexican Wolf pups is being implemented by the IFT to further recovery efforts of the Mexican Wolf population as prescribed in the 2017 Mexican Wolf Recovery Plan. Based on the best available science, the Mexican Wolf Recovery Plan identifies a target of 22 wolves released from captivity into the wild that survive to breeding age (2 years old) as one of the criteria needed to delist the Mexican Wolf from the Endangered Species List. Since the first cross-foster of two pups in 2014, the IFT has documented a minimum of 10 cross-fostered wolves surviving to the end of the year and being recruited into the wild population. The IFT does not capture and collar every wolf pup that survives, so there are likely other cross-fostered wolves that currently live in the population that have not yet been documented.
By the Numbers:
Mexican wolves were first released back into the wild in 1998. In 2019, population surveys estimated a minimum of 163 Mexican Wolves occur in Arizona and New Mexico.
Since 2014, there have been 50 genetically diverse wolf pups cross-fostered into the wild in Arizona and New Mexico.
The IFT has documented survival in four of the seven packs that received cross-fostered pups in 2020.
The IFT is actively monitoring 14 cross-fostered wolves that are fitted with radio collars.
At least five cross-fostered wolves have survived to breeding age, resulting in multiple litters of genetically-diverse pups born in the wild.
The Mexican Wolf Interagency Field Team is comprised of staff from the U.S. Fish and Wildlife Service, New Mexico Department of Game and Fish, USDA Forest Service, USDA-Animal and Plant Health Inspection Service, Wildlife Services, White Mountain Apache Tribe, and AZGFD.