Vegetation height and structure drive foraging habitat selection of the lesser kestrel (Falco naumanni) in intensive agricultural landscapes

Abstract

Habitat selection in animals is a fundamental ecological process with key conservation implications. Assessing habitat selection in endangered species and populations occupying the extreme edges of their distribution range, or living in highly anthropized landscapes, may be of particular interest as it may provide hints to mechanisms promoting potential range expansions. We assessed second- and third-order foraging habitat selection in the northernmost European breeding population of the lesser kestrel (Falco naumanni), a migratory falcon of European conservation interest, by integrating results obtained from 411 direct observations with those gathered from nine GPS-tracked individuals. The study population breeds in the intensively cultivated Po Plain (northern Italy). Direct observations and GPS data coincide in showing that foraging lesser kestrels shifted their habitat preferences through the breeding cycle. They positively selected alfalfa and other non-irrigated crops during the early breeding season, while winter cereals were selected during the nestling-rearing phase. Maize was selected during the early breeding season, after sowing, but significantly avoided later. Overall, vegetation height emerged as the main predictor of foraging habitat selection, with birds preferring short vegetation, which is likely to maximise prey accessibility. Such a flexibility in foraging habitat selection according to spatio-temporal variation in the agricultural landscape determined by local crop management practices may have allowed the species to successfully thrive in one of the most intensively cultivated areas of Europe. In the southeastern Po Plain, the broad extent of hay and non-irrigated crops is possibly functioning as a surrogate habitat for the pseudo-steppe environment where most of the European breeding population is settled, fostering the northward expansion of the species in Europe. In intensive agricultural landscapes, the maintenance of alfalfa and winter cereals crops and an overall high crop heterogeneity (deriving from crop rotation) is fundamental to accommodate the ecological requirements of the species in different phases of its breeding cycle.

Within‐colony segregation of foraging areas: from patterns to processes

“…Second, we tested whether individuals from the two nest clusters differed in the bearing taken when departing on foraging trips, and then compared the bearings taken by individuals when leaving the nesting site to those of concomitantly departing and returning individuals. Indeed, lesser kestrels are non‐territorial during foraging, have been shown to use social information obtained at the colony in some contexts (nest site selection, Aparicio et al 2007, Morinay et al 2021, antipredator vigilance, Campobello et al 2012), and are known to sometimes forage in groups (typically in patches with ephemeral and high prey density, in fields being ploughed; Morganti et al 2021, Cioccarelli et al 2022). Hence, we might expect them to use foraging social information obtained at the colony, by eavesdropping on the departure or return bearings of neighbouring breeders.…”