No place like home: an experimental comparison of reintroduction strategies using snakes

Abstract

Summary1. The practice of deliberately moving animals from one site to another for conservation is increasing as a tool to re-establish extirpated populations. Resource managers are faced with developing strategies for reintroduction attempts, but often lack experimentally derived evidence upon which to base decisions. 2. Using the northern water snake Nerodia sipedon sipedon in the USA, we compared the behaviour and performance of resident snakes with that of individuals translocated directly from the wild to a nearby nature reserve or reared in captivity prior to translocation. 3. Both translocated groups had low survivorship relative to resident snakes, but the proximal causes of their poor performance differed considerably. Captive-reared snakes exhibited restricted surface activity and movements and abnormal habitat use, and ultimately failed to maintain appropriate body temperature and body mass, with high mortality associated with the overwintering period. Wild snakes directly translocated to an unfamiliar site maintained body temperatures and growth comparable with residents, but their more extensive movements resulted in frequent excursions off reserve and high mortality. 4. Synthesis and applications. We contend that an individual's prior experience is an important factor in determining their behaviour and performance during the phase of early establishment at an unfamiliar site. This suggests the existence of common underlying mechanisms influencing the outcome of reintroduction attempts, and provides a potentially useful framework for improving reintroduction efforts. Resource managers would likely improve success of reintroductions by matching habitats (and associated resources and conditions) between source and release sites, by temporarily confining animals in enclosures that force new associations to be made while limiting exploratory wanderings, or by enrichment of environmental conditions in captivity.

Movement patterns and home range of captive-bred Amur ratsnake (Elaphe schrenckii) juveniles in the natural habitat

“…This movement pattern is similar to previous results (King et al 2004, Roe et al 2010. For example, captive-bred juveniles of the northern water snake (N. sipedon) showed low activity and used very limited areas during their early phase of release (Roe et al 2010).…”

“…We only used the juveniles who successet al (2004) have studied the movement patterns, home ranges, uses of structural features, and hibernation mortality of captive-bred eastern massasauga (Sistrurus catenatus) in Wisconsin. Recently, Roe et al (2010) compared the movement and home range of captive-bred and wildcaught juveniles of the northern water snake (Nerodia sipedon). These studies have shown that rehabilitation projects combined with a successful captive breeding program might be applicable for the rehabilitation of endangered reptile species.…”

“…The study, capture, handling, and release of the Amur ratsnakes in the Chiaksan and Woraksan National Parks were permitted by the Wonju Regional Environmental Office. The snake handling followed the "Guidelines for Use of Live Amphibians and Reptiles the Korean ratsnake (Elaphe schrenckii) and its applisnake (Roe et al 2010). In the study, large juveniles had relatively small home ranges.…”

Post-release movements of captive-born European mink Mustela lutreola

“…The lack of enclosure effect on short-term movements might be interpreted as the enclosures lacking the appropriate stimulus for the development of familiarity, or preference, for the local habitat (Stamps & Swaisgood 2007, Roe et al 2010 or that the cage environment at Tallinn Zoo was sufficient. Alter natively, the facts that enclosure animals were more often found further from aquatic habitats, did not make longer daily movements, but appeared to cover slightly larger areas over time, suggest that enclosure animals may simply have been exploring more (and were perhaps better prepared for 'learning' about their new environment than were caged animals, see e.g.…”

“…Biggins et al 1999, Stoin-ski & Beck 2004; see also Roe et al 2010), after which they may be released with or without further support in either a 'soft' release (with shelter and/or food) or a 'hard' release (with no support). The theoretical basis for this approach is that experience early in life (but not necessarily during any particular sensitive pe riod) affects future habitat preferences and individual performance, or behaviour, in that habitat (Davis & Stamps 2004, Stamps & Swaisgood 2007.…”