Assessing the relationships between weather, food limitation and breeding ecology in an Arctic top predator Open Access

[摘要] A long term project being conducted on a population of Peregrine Falcons (Falco peregrinus) breeding near Rankin Inlet, Nunavut, Canada, has chronicled a steady decline in annual productivity over 30 years. By documenting the direct effects of summer rainfall on nestling mortality, a recent study on this population suggested that an increasing frequency of heavy rainfall may partially explain the observed declines. If the lower trophic communities that falcons rely on as prey are also affected by rainfall, reductions in food availability may be further limiting peregrine breeding success. The intent of this project was to determine if the Rankin Inlet population is generally food limited, and to determine if food limitation varied according to yearly precipitation. To answer these questions, I implemented a food supplementation experiment over three breeding seasons (2013 – 2015). After nestlings hatched each year, randomly selected broods periodically received an amount of commercially produced Common Quail (Coturnix coturnix) that correlated to 50% of the brood’s age-specific energetic demand. The first two breeding seasons in which data were collected were uncharacteristically dry with total monthly rainfall amounts well below the 30 year average. The final season of data collection occurred in a summer with total monthly rainfall exceeding the 30 year average, and thus provided us with an opportunity to contrast food limitation across varying environmental conditions. Over 3 years, I food supplemented a total of 93 individuals from 29 broods, and monitored 100 individuals from 32 broods that were not supplemented. Supplementation resulted in higher nestling survival, and more consistent growth between years. Based on these results, I suggest that the Rankin Inlet population is generally food limited during the breeding season. Although I recorded an effect of rainfall on nestling growth, I failed to detect a relationship between nestling mortality and rainfall-induced food limitation. However, population-wide decreases in brood size during the wet year may have acted in a compensatory manner by reducing nestling energetic requirements. Overall, this project increases our understanding of how food availability relates to Peregrines breeding in the Arctic, and outlines important variables that influence productivity.

[发布机构] University of Alberta

[效力级别] Raptor