Evidence of colony- and individual-level variation in habitat usage of Atlantic Puffins (Fratercula arctica)

Seabirds are among the most threatened avian taxa. Effective seabird conservation requires an understanding of both seabird distributions and habitat usage. Species distribution models can help identify important areas for protection and manage threats to seabird populations. However, populations of the same species may differ in their response to the environment, reducing the transferability of such models. In addition, individual-level responses to habitat may vary both within and between animal populations. Atlantic Puffins (Fratercula arctica) are classed as vulnerable to global extinction and a UK red-listed bird of concern. Consequently, a greater understanding of their at-sea habitat usage is a conservation priority. We used GPS tracking data from four UK Puffin colonies to construct species distribution models and examine colony- and individual-level variation in habitat usage in response to a suite of environmental covariates (chlorophyll-a concentration, sea surface temperature (SST), water depth, seabed slope, current velocity, and SST front gradient). The most consistent colony-level response was a negative association between habitat usage and chlorophyll-a concentration (observed at 3 out of 4 colonies). Responses to other environmental covariates were less consistent across colonies. Among individual variation in foraging range per trip was low, but we observed individual variation in habitat usage in response to almost all environmental covariates examined. Within each colony, we also identified distinct clusters of space-use across different groups of individuals. Different Puffin colonies and individuals are not ecologically equivalent. Therefore, perturbations to the marine environment are likely to have disproportionate effects on certain colonies and/or individuals. Incorporating colony- and individual-level variation will thus be essential for marine conservation efforts.