Effect of habitat on breeding success and fledging age in Oystercatchers (Haematopus ostralegus) breeding in the south, west, and Westfjords of Iceland

Abstract

Iceland is a globally important breeding area for a variety of ground-nesting wader species.This includes Eurasian Oystercatchers (Haematopus ostralegus), which are unique wadersin that they: hatch semi-precocial chicks dependent on parental feeding, are partiallymigratory, and utilize both coastal and inland breeding territories. This system presents aunique opportunity to study the influences that differences in habitat quality have onbreeding success and behavior of chicks. Little is known about patterns of habitat selectionof wader species breeding in Iceland, or comparative breeding success of oystercatchersutilizing different habitats. This study identified and compared the breeding success andfledging age of oystercatchers breeding in different habitat types in the South, West, andWestfjords of Iceland. Additionally, provisioning data was obtained for the Westfjordsregion. The results show that productivity was influenced by habitat (p<0.001) and byregion (p<0.001), and was higher in regions of predominantly coastal habitat use.Additionally, fledging success was influenced by habitat (p<0.001) and by region (p<0.01).Differences on predation rates and resource availability are most likely driving variances inreproductive success. Oystercatchers in the Westfjords increasingly fed their chicks small,coastal prey as chicks grew, which may also reflect an unavailability of terrestrial preyitems, but provisioning studies should continue in the future to provide further informationon resource use. Fledging age was similar across regions and habitat types, but more datais needed to explore this further. Understanding how oystercatchers are utilizing differentresources, and how that might change and be translated into breeding success, is vital forunderstanding their population ecology and effectively contributing to managementdecisions of important bird areas.