Breeding population trends and pre-migration roost site survey of the Red-footed Falcon in Hungary

Abstract The Red-footed Falcon is a facultatively colonial species that exploits rookeries, artificial nest-box colonies and solitary corvid nests for breeding. Moreover, the remain gregarious in the post breeding period using communal roost sites prior to migration. We developed and implemented a survey protocol to allow to precisely estimate the number of breeding pairs in all three breeding types and to assess large scale spatio-temporal changes in roost site usage. Our results show that the lowest number of breeding pairs (558) was in 2006. However, in 2014 the number of pairs showed a two fold increase, mainly due to a large scale nest-box programme implemented in the past decade. We identified a total of 105 roost sites throughout the country. The number of birds peaked in the second week of September in the past 10 years. We formulate a recommendation to maintain population monitoring efficiency by reducing the frequency of full surveys to 5 years and using designated study areas to control for temporal trends in between.