Dynamic vegetation cover and decline in common eider breeding numbers in Nova Scotia, Canada

The American common eider ( Somateria mollissima dresseri) is a colonially nesting sea duck breeding on islands in the coastal regions of Atlantic Canada. Declines colony size have been pronounced some parts its range, notably Nova Scotia, and may be attributable to variety interconnected factors including changes habitat conditions. Using surveys collected two decades apart, we compared types, availability, use by eiders 16 that supported >1600 nests 1992–1993, but 830 2013. While general patterns remained consistent (e.g., preferences exhibited for Low Shrubland Grassland habitats, avoidance forest or beach habitats), overall vegetation cover declined, relative were inconsistent across islands. Three with greatest change had cormorant Phalacrocorax spp.) colonies 2013 not there earlier years. We suggest vegetation, cases facilitated formation, influenced susceptibility females predators, these contributing local population declines.