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Methods used to quantify the stress response in animals are vital tools in many areas of biology. Here we describe a new method of measuring the stress response, which provides rapid results and can be used in the field or laboratory. After a stressful event, we measure the capacity of circulating leukocytes to produce a respiratory burst in vitro in response to challenge by phorbol myristate acetate (PMA). During the respiratory burst leukocytes produce oxygen free radicals, and the level of production can be measured directly as chemiluminescence. When in vitro PMA‐stimulated whole blood chemiluminescence is measured directly after a stressful event, we define the response as the leukocyte coping capacity (LCC). In an experiment badgers (Meles meles), which were caught as part of an on‐going population study, were either transported to a central site prior to blood sampling or blood was collected at their site of capture. Transported animals had a significantly lower LCC and showed changes in leukocyte composition that were indicative of stress. We conclude that the stress of transport reduced LCC in badgers and that LCC serves as a quantitative measure of stress. Potential applications of this method are discussed.

Re-introductions of captive-bred animals are increasingly common in wildlife conservation and it is important that they fulfil their potential. To foster this goal we examined variations in stress levels in a captive-bred population of water voles Arvicola terrestris in response to housing conditions and radio-collaring, using weight loss and leukocyte coping capacity (LCC) as measures of relative stress, to investigate the impacts of housing conditions, handling and radio-collaring on this species. Thirty-eight water voles (22 males and 16 females) were used in the investigation, 25 housed in outdoor enclosures and 13 in laboratory cages. During the 6-week study, LCC, body weight and urine refractive index (URI, an indicator of hydration levels) were recorded once a week for each individual in weeks 1, 2, 4 and 6. After the first sample, radio-collars were attached to 20 individuals (10 males and 10 females) taken from both housing types. Throughout the experiment laboratory-cage housed voles weighed less, had lower LCC scoresindicating a reduced ability to combat infection -and had higher URIs than outdoor-enclosure voles. This suggests that the laboratory-cage voles were more stressed and dehydrated than the outdoor-enclosure voles. Weights and LCC scores of both housing groups decreased as the study progressed, suggesting that elements of the study, such as repeated handling, may have caused stress to both groups. Evidence suggested a short-term effect of radio-collaring on immunocompetence. We conclude that captive housing conditions, repeated manipulation and radio-collaring had demonstrable physiological effects on the water voles studied. We recommend that the effects of husbandry and tagging practices upon captive-bred mammals be closely studied as part of the quest to improve the success of the re-introductions to which they contribute.

A naturally functioning riparian zone is essential for the ecological health of a river, filtering pollutants, supplying organic matter and providing a structural habitat for wildlife. Most lowland rivers would also naturally flood the riparian zone at regular intervals, thereby providing direct inputs of nutrients and water that create additional habitats and breeding opportunities for riverine species. We examined the relationship between the quality of the riparian habitat and foraging and activity of bats (Chiroptera), which are good indicators of ecosystem health. Twenty paired sites in the Rivers Lee and Colne catchments in England were selected to test the hypothesis that degradation in the quality of riparian habitat reduces foraging and activity in bats; paired sites were similar in terms of size, flow rate and water chemistry but differed in the quality of their riparian zones. AnaBat detectors were used to measure bat activity from 30 min before dusk to 30 min after sunrise on the same night at paired sites because recording frequency-divided bat echolocation calls in real time allows large amounts of data to be collected over long time periods in a digitized format. Significantly more feeding buzzes were recorded in sites with better quality riparian zones; no differences in overall bat activity were found between the two habitat types. Pipistrellus pipistrellus and Pipistrellus pygmaeus accounted for 96% of bat passes. Pipistrellus pygmaeus was significantly more active in high quality sites than P. pipistrellus; there was no difference between the two species in poor quality sites. We show that the quality of riparian buffer zones is important for the activity and feeding behaviour of pipistrelle bats.

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