Changes in the number and habitat of Peregrine Falcon nest sites during 35 years in Hiroshima Prefecture

Abstract

We surveyed nesting Peregrine Falcons Falco peregrinus in Hiroshima Prefecture from 1988 to 2023. We compared the number of falcon nests during the first (up to 2007) and second (2008-2023) survey periods. The number of falcon nests increased from 25 to 39 in the mainland area, especially in quarries, where the nest sites increased from 8 to 23. We deduce that a recent rise in quarrying activity on the mainland increased the potential nesting sites for peregrines, thus inviting falcons to attempt nesting more frequently in quarries. Nesting sites for falcons had a high continuity rate for those on natural cliffs or quarries, but when nesting in man-made structures the continuity rate was low. No clear trend was observed in the directionality of the falcons’ nesting sites