Assessment of releases of translocated and rehabilitated Yucatán black howler monkeys (Alouatta pigra) in Belize to determine factors influencing survivorship.

Rehabilitation and reintroduction have become important to the management and welfare of primates worldwide. However, the suitability and success of these practices must be evaluated to determine their effectiveness as well as to improve programs and methods, as little is known about the factors influencing survival of released individuals. Between 2011 and 2014, 28 howler monkeys, Alouatta pigra, were released at Fireburn Reserve, northern Belize by the Primate Rehabilitation Centre of Belize: Wildtracks. From March to August 2015, field trips were made to determine the number and identity of surviving individuals to assess whether differences in individual outcomes (survived or disappeared) could be associated with specific characteristics or backgrounds of the monkeys. Fourteen of the twenty rehabilitated monkeys and seven of the eight translocated monkeys were found alive. The proportion of surviving individuals was not significantly different between rehabilitants and translocated animals, males and females, former pets and wild animals, short- and long-term rehabilitants, or different ages at release or intake. As mortality was low and none of the general factors analyzed influenced survivorship, it is suggested that chance or individual traits may be important in the outcomes of releases. This study provides an example of successful population reintroduction from both rehabilitation and translocation programs, and the first analyses of characteristics impacting the success of releases of howler monkeys.