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  1. Cooke, Steven (Ed.)
    Abstract Physiological metrics are becoming popular tools for assessing individual condition and population health to inform wildlife management and conservation decisions. Corticosterone assays can provide information on how animals cope with individual and habitat-level stressors, and the recent development of feather assays is an exciting innovation that could yield important insights for conservation of wild birds. Due to the widespread enthusiasm for feather corticosterone as a potential bioindicator, studies are needed to assess the ability of this technique to detect meaningful differences in physiological stress across a variety of stressor types and intensities. We examined feather corticosterone from 144 individualsmore »among the 13 known breeding populations of Hawaiian gallinule (Gallinula galeata sandvicensis), an endangered waterbird, on the island of O‘ahu. These ecologically independent subpopulations are known to have low genetic connectivity and movement rates and differ largely across a number of important conditions, including level of predator management, human disturbance, proximity to urban development and conspecific population density. This system is well suited for assessing the performance of feather corticosterone as a bioindicator of different known habitat-level threats common to this and many other conservation-reliant species. We found no statistically significant relationship between feather corticosterone and level of predator control, level of human disturbance, gallinule population density, percent urban cover or body condition across all sites despite the substantial difference in stressor magnitude in our dataset. We did find that gallinules in habitats with larger population densities were in worse body condition. These findings suggest that feather corticosterone is not a consistent indicator of anthropogenic impacts on populations. Furthermore, they suggest that feather corticosterone may be a poor bioindicator of known habitat-level threats for Hawaiian gallinules and that it should be used with caution in other avian taxa of conservation concern.« less
  2. Cooke, Steven (Ed.)
    Abstract Wild animals brought into captivity frequently experience chronic stress and typically need a period of time to adjust to the conditions of captivity (restraint, artificial lighting, altered diet, human presence, etc.), to which they may never fully acclimate. Changes in mass, the hypothalamic–pituitary–adrenal axis and heart rate parameters have been observed over the first week in newly captive house sparrows (Passer domesticus). In this study, we tested the effects of two drugs, diazepam and mitotane, in preventing the chronic stress symptoms caused by captivity, compared with oil-injected control animals. Diazepam is an anxiolytic that is widely prescribed in humansmore »and other animals and has been shown in some cases to reduce physiological stress. Mitotane is an agent that causes chemical adrenalectomy, reducing the body’s capacity to produce glucocorticoid hormones. Our mitotane treatment did not cause the expected change in corticosterone concentrations. Baseline corticosterone was higher after a week in captivity regardless of the treatment group, while stress-induced corticosterone did not significantly increase above baseline after a week in captivity in any treatment group. However, mitotane treatment did have some physiological effects, as it reduced the resting heart rate and the duration of the heart rate response to a sudden noise. It also prevented the increase in nighttime activity that we observed in control animals. There was no effect of diazepam on corticosterone, resting heart rate, activity or heart rate response to a sudden noise, and no effect of either treatment on the sympathetic vs parasympathetic control of the resting heart rate. Together, these data suggest that mitotane, but not diazepam, can have a modest impact on helping house sparrows adapt to captive conditions. Easing the transition to captivity will likely make conservation efforts, such as initiating captive breeding programs, more successful.« less