Second-calendar-year Eleonora's Falcons attending breeding colonies in Sicily

摘要

Surveys of breeding colonies of Eleonora's Falcons Falco eleonorae in the Aeolian and Pelagie Islands, Sicily, showed an unexpectedly high proportion of second-calendar-year (2CY) birds attending breeding colonies. On average, around 20% of all aged birds at breeding colonies were 2CYs. There is evidence that this proportion is increasing at one colony, which may be an early warning signal of colony decline. Some birds attempted to breed in their second calendar-year; the outcome of these pairings isunknown.