Group Prerelease Training Yields Positive Rehabilitation Outcomes Among Juvenile Mantled Howlers (Alouatta palliata)

Outcomes for an arboreal folivore after rehabilitation and implications for management

Wildlife rehabilitation is a critical part of animal welfare that contributes to species conservation. Despite the resources that go into rehabilitation, how animals fare after release from care is unknown. This is particularly true for cryptic arboreal species where specialist diets in care and low detectability in the wild present challenges for both care and post-release monitoring. We evaluated post-release outcomes for koalas and assessed if koalas were fed appropriately while in care. We monitored 36 koalas that had experienced one of three categories of medical intervention (none, minor, major) during rehabilitation. We examined the drivers of (i) koala survival and (ii) movements post-release, and (iii) evaluated variation between the species of browse fed in care versus browse selected by koalas in-situ. Overall, the post release survival rate of koalas was 58.5%, with only koalas that received medical intervention experiencing mortality. A critical threshold for mortality occurred at two weeks post-release and mortality was related to the measurable indicators of low body condition and poor climbing ability at time of release. In the month following their release, animals translocated furthest from their capture point moved the furthest. There was poor overlap between the tree species that koalas were fed in care and those they utilized post-release. We provide recommendations to address critical gaps in rehabilitation practices, as well as priorities for monitoring animals post-release to improve outcomes for arboreal folivores.

Conservation and the 4 Rs, which are rescue, rehabilitation, release, and research

Vertebrate animals can be injured or threatened with injury through human activities, thus warranting their "rescue." Details of wildlife rescue, rehabilitation, release, and associated research (our 4 Rs) are often recorded in large databases, resulting in a wealth of available information. This information has huge research potential and can contribute to understanding of animal biology, anthropogenic impacts on wildlife, and species conservation. However, such databases have been little used, few studies have evaluated factors influencing success of rehabilitation and/or release, recommended actions to conserve threatened species have rarely arisen, and direct benefits for species conservation are yet to be demonstrated. We therefore recommend that additional research be based on data from rescue, rehabilitation, and release of animals that is broader in scope than previous research and would have community support.

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.