Captive Housing during Water Vole (Arvicola terrestris) Reintroduction: Does Short-Term Social Stress Impact on Animal Welfare?

Abstract

BackgroundAnimals captive bred for reintroduction are often housed under conditions which are not representative of their preferred social structure for at least part of the reintroduction process. Specifically, this is most likely to occur during the final stages of the release programme, whilst being housed during transportation to the release site. The degree of social stress experienced by individuals during this time may negatively impact upon their immunocompetence.Methodology/Principal FindingsWe examined two measure of stress - body weight and Leukocyte Coping Capacity (LCC) - to investigate the effects of group size upon captive-bred water voles destined for release within a reintroduction program. Water voles were housed in laboratory cages containing between one and eight individuals. LCC scores were negatively correlated with group size, suggesting that individuals in larger groups experienced a larger degree of immuno-suppression than did individuals housed in smaller groups or individually. During the course of the study mean body weights increased, in contrast to expectations from a previous study. This was attributed to the individuals sampled being sub-adults and thus growing in length and weight during the course of the investigation.Conclusions/SignificanceThe reintroduction process will inevitably cause some stress to the release cohort. However, for water voles we conclude that the stress experienced may be reduced by decreasing group size within captive colony and/or transportation housing practises. These findings are of significance to other species' reintroductions, in highlighting the need to consider life-history strategies when choosing housing systems for animals being maintained in captivity prior to release to the wild. A reduction in stress experienced at the pre-release stage may improve immunocompetence and thus animal welfare and initial survival post-release.

Quantifying capture stress in free ranging European roe deer (Capreolus capreolus)

“…The obtained LCC responses match indications from previous studies on Atlantic salmon ( Salmo salar ) [50], European badger ( Meles meles ) [31], Rhesus macaque ( Macaca Mulatta ) [51], European water vole ( Arvicola terrestris ) [7], water voles ( Arvicola terrestris ) [52], as well as on humans [33, 53, 54]. Interestingly, estimates of roe deer neutrophil production of reactive oxygen species (ROS) due to secondary challenge peak mostly after five (11%) or 10 min (78.5% of all animals).…”

The Capybara Paradigm: From Sociality to Sustainability

“…Perhaps the most thorough attempt to evaluate, and then improve, the welfare of harvested wildlife was the mix of behavioral, physiological, and biochemical measures made of another South American mammal, the vicuna, Vicuna vicuna , which is shorn for its wool Gordon 2009 ) . Subsequently, more re fi ned immunological techniques for measuring stress, and thereby reducing it, have been developed (e.g., Gelling et al 2010 ) . These techniques would be helpful in evaluating the pros and cons of capybara harvests and farming, and are thus relevant to the interwoven aims of conservation and animal welfare (McLaren et al 2006 ) , and to the even more challenging aim of further integrating with them the wider goals of development.…”

Impact of Capture and Transportation Methods on Survival of Small Rodents During Relocation Events

“…Additionally, small rodents are sometimes captured and translocated to bolster small populations of threatened or endangered species (e.g., Gelling et al, 2010). Maximizing survival associated with these capture and subsequent transportation events is necessary to efficiently utilize limited resources while ensuring that animal welfare requirements are met.…”

“…Survival of rodents during transportation events is directly influenced by stress levels associated with this event (Morgan and Tromborg, 2007;Gelling et al, 2010); minimizing stress should be a key concern when developing transportation protocols. One potential method to reduce stress levels of captured animals is to minimize the time spent in captivity and subsequent transportation.…”

“…Not surprisingly, transportation of small rodents over long distances can result in high mortality rates given the added stress of a new environment combined with environmental conditions that might be more extreme than what they are accustomed to (Gelling et al, 2010). For example, a previous attempt to transport voles from California to Colorado resulted in the mortality of all captured voles (T. Primus, USDA-National Wildlife Research Center, pers.…”