Comparison of two release methods for Antilocapra americana (Artiodactyla: Antilocapridae) in Coahuila, México.
The reintroduction of missing mammal species in former habitats has recently been of high interest. In Mexico, there have been several attempts to reintroduce Antilocapra since 1967, but until now none of the trials has been successful. Nowadays, different releasing methods have been practiced for mammal species, including soft and hard release ones. The aim of this study was to provide new information, and to evaluate the success of a recent release. The study was based on the monitoring of 100 individuals (70 females, 30 males) captured in New Mexico, USA, to be released in Maderas del Carmen, Coahuila, Mexico, in two different groups. The first group (fast release) of 45 specimens (20 females, 25 males) was released in the valley at the beginning of March 2009. The second one (soft release), with 55 individuals (50 female, 5 male), was released in March 2010. For both groups, we compared the mortality rate between dispersal and soft-release vs. hard-release methods. Our results showed that the release with adaptation gave highly significant results (χ2= 2, α= 0.05, p= 0.0001)). The comparison of mortality and dispersion among both methods was highly contrasting: with soft-release we obtained 4 % and 13 % of success, against 23 % and 46 %, respectively. Considering these results, we recommend the soft-release method to be used in future reintroduction attempts of Antilocapra, since more than 50 % of specimens from hard-releases died because of capture stress, or were dispersed, and thus reduced the reintroduction success chances.