Habitat selection and foraging site fidelity in Caspian Terns (Hydroprogne caspia) breeding in the Baltic Sea

Habitat preferences and foraging strategies affect population-level space use are therefore crucial to understanding population change implementing spatial conservation management actions. We investigated the breeding season habitat preference site fidelity of under-studied threatened, Baltic Sea Caspian Terns (Hydroprogne caspia). Using GPS devices, we tracked 20 adult individuals at two colonies, in Sweden Finland, from late incubation through chick-rearing. Analyzing movements during this period, describe trip characteristics for each colony, daily metrics effort, use, fidelity. found that time spent away colony increased throughout season, with colony-level differences terms distance travelled per day. In general, terns selected shallow waters between 0–5 meters depth certain using inland lakes foraging. show, first time, individual faithful sites highly repeatable their regarding These results fill important knowledge gaps at-risk population, extend our general ecology widespread species.