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ESR prepress abstract   -  DOI: https://doi.org/10.3354/esr01108

Spatial ecology of endangered roseate terns and foraging habitat suitability around a colony in the western North Atlantic

Isabeau Pratte*, Robert A. Ronconi, Shawn R. Craik, Julie McKnight

*Corresponding author:

ABSTRACT: Predicting habitat suitability and understanding habitat utilization are important to inform and orient conservation and management decisions for the recovery of endangered species. In North America, roseate tern Sterna dougallii is listed as endangered in both the Northeastern United States and Canada where little is known about the foraging spatial ecology of the species. We equipped roseate terns breeding at North Brother Island, the main Canadian colony, during incubation with miniature GPS tracking devices. Our aim was to characterize the spatial foraging ecology of the species, identify marine zones of importance and develop a habitat suitability model around the colony. Our results provide novel, high resolution information on individual foraging trips, notably showing that individuals restrict their range around the colony (15.4 km), while performing multiple foraging trips: up to 11 daytime trips and a maximum total of 152.9 km traveled per day. Roseate terns concentrated their foraging effort around the colony, and further south along the coast to the Cockerwit Passage. Using distance from colony, sea surface temperature, distance from land, bathymetry and subtidal substrate type as covariates in a habitat suitability model, a high proportion of the deviance was explained (72.4%); the model also predicted high occurrence of foraging near the colony, in Cockerwit Passage, and at additional sites to which the birds were not tracked. Along with the description of important marine areas for roseate terns nesting on North Brother Island, this habitat suitability model provides a relevant and essential context for understanding roseate tern habitat use in a broad sense, but with a focus on habitat requirements during incubation.