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

Background: Animals 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 Findings: We 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 immunosuppression 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/Significance: The 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. The 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

Health and welfare in reintroductions : Lessons from small mammals

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The sampling design of the study.

<p>The table presents the number of cages (37 in total) of each type, defined by cage size and number of occupants that were sampled. Only data from the first individual sampled from each cage were analysed, so the number of cages also represents the number of individuals sampled within each level of “Number in cage”.</p

Paired-t-tests for each stress measurement at different time periods; pre-release (0), first recapture (1) and last recapture (4 OR 5). Captive-bred animals only.

*<p> = significant at the 0.05 level; ** = significant at the 0.01 level; *** = significant at the 0.001 level.</p

Two-way between groups ANOVA.

$<p>More stringent value of <i>p</i> = 0.01 applied to account for lack of homogeneity of variances assumed by the test, indicated by a Levene’s value <0.05.</p>*<p> =  significant at the 0.05 level; ** =  significant at the 0.01 level; *** =  significant at the 0.001 level.</p><p>All Adult animals from capture session two onwards (when both captive-bred and wild-born are present; excluding pregnant or lactating females), sex, origin, site quality and session. Only two-way interactions and main effects are considered.</p

Number of animals sampled pre-release and in each subsequent post-release session.

<p>Number of animals sampled pre-release and in each subsequent post-release session.</p

Bovine tuberculosis (Mycobacterium bovis) in British farmland wildlife:The importance to agriculture

Bovine tuberculosis (bTB) is an important disease of cattle and an emerging infectious disease of humans. Cow- and badger-based control strategies have failed to eradicate bTB from the British cattle herd, and the incidence is rising by about 18% per year. The annual cost to taxpayers in Britain is currently £74 million. Research has focused on the badger as a potential bTB reservoir, with little attention being paid to other mammals common on farmland. We have conducted a systematic survey of wild mammals (n=4393 individuals) present on dairy farms to explore the role of species other than badgers in the epidemiology of bTB. Cultures were prepared from 10 397 samples (primarily faeces, urine and tracheal aspirates). One of the 1307 bank voles (Clethrionomys glareolus) live-sampled, and three of the 43 badgers (Meles meles), yielded positive isolates of Mycobacterium bovis. This is the first time the bacterium has been isolated from the bank vole. The strain type was the same as that found in cattle and badgers on the same farm. However, our work indicates that the mean prevalence of infectious individuals among common farmland wildlife is extremely low (the upper 95% confidence interval is ≤2.0 for all of the abundant species). Mathematical models illustrate that it is highly unlikely the disease could be maintained at such low levels. Our results suggest that these animals are relatively unimportant as reservoirs of bTB, having insufficient within-species (or within-group) transmission to sustain the infection, though occasional spill-overs from cattle or badgers may occur