Hi Jerry! U.S. Fish and Wildlife Service (FWS) cross-fostered 2 Mexican wolf pups in 2014, 6 in 2016, 4 in 2017 and 8 in 2018. At least 4 of these these 20 pups are known to have survived, but to date FWS can confirm only a single cross-fostered pup surviving to produce its own pups. The FWS states that 37.5% of pups (both captive and wild born) cross-fostered into wild litters have survived to breeding age.