The potential for the use of population health indices in the Predatory Bird Monitoring Scheme: a Predatory Bird Monitoring Scheme (PBMS) report

摘要

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife.udEach bird that is submitted to the scheme is given a post-mortem examination during which approximately 60 macroscopic observations and measurements are made. The information gathered during this examination could potentially be used to monitor health status of the birds at the time of their death or at a particular stage of their development. In the current study, we focused on examining potential health indicators for the sparrowhawk, Accipiter nisus, as a candidate species partly because we have a long track record of collecting carcasses and eggs of this species, and so hold a substantial associated post-mortem (PM) observations and egg morphometric data sets. This species is sexually dimorphic, another reason for using it as a candidate species as it allowed us to investigate if the various health indices would need to be (and could be) defined separately by age class and sex. udWe were able to establish baseline “norms” in the form of Shewhart charts for indicators that could be broadly categorised as indicators of change in: (i) population demography because of altered recruitment, survival and mortality (measures were sex ratio, proportion of first-year birds, proportion deaths from starvation or disease, eggshell index); (ii) nutritional status (measures were body weight, fat score, condition index) and (iii) physiological stress (fluctuating asymmetry). The measurements necessary to calculate these indices are routinely captured by the PBMS through direct input into an Oracle database at the time of PM examination. We also explored the potential for annual monitoring of feather corticosterone as a simple effects biomarker for environmental stress, including environmental contaminants, but further work and resource would be needed to incorporate any such measure into annual health surveillance monitoring. ududWe outline how the health indices described here could be reported in real-time and extended to other species to provide surveillance across different trophic strategists, and ecosystems. This report is intended to prompt debate about the type of population health indices that may be of use in assessing environmental health. It is not intended to be definitive in terms of which should be used.ud