A few long versus many short foraging trips: different foraging strategies of lesser kestrel sexes during breeding

Abstract

BackgroundIn species with biparental care both members of the breeding pair cooperate to raise the offspring either by assisting each other in every reproductive task or by specializing in different ones. The latter case is known as reproductive role specialization. Raptors are considered one of the most role-specialized groups, but little is known about parental behavior away from the nest. Until the advent of biologgers, avian role specialization was traditionally studied with direct observations at the nest because of the difficulties of following and recording the behavior of free-ranging individuals. In this paper we analyze how the role specialization of the lesser kestrel (Falco naumanni) influences foraging movement patterns throughout the breeding season. We tracked 30 lesser kestrel breeders from two breeding colonies using high-frequency GPS-dataloggers during four consecutive breeding seasons.ResultsWe found no differences between sexes in lesser kestrel foraging movements early in the breeding season before the formation of the breeding pair. However, we observed sexually distinct foraging movement strategies later in the breeding season once breeding pairs were formed. Lesser kestrel males performed a large number of short foraging trips while females made a few long ones. This maximized the provisioning rate by males to feed their mates and offspring. Meanwhile, lesser kestrel females spent more time at the colony than males in order to defend the nest, incubate the eggs and brood the nestlings. Females also helped their mates to provision the nestling once these had grown and required more food and less protection. Furthermore, lesser kestrels showed a sexual spatial segregation in foraging areas, with males foraging closer to the colony than females.ConclusionsThe lesser kestrel responds to changes in energy demand throughout the breeding season with its foraging movement strategy, but in a different way depending on parental sex. The sexual spatial segregation observed is likely to be the result of an adaptive foraging strategy based on role specialization to reduce prey depletion close to the colony and intersexual competition in order to improve breeding success.Electronic supplementary materialThe online version of this article (doi:10.1186/s40462-017-0100-6) contains supplementary material, which is available to authorized users.

How can the home range of the Lesser Kestrel be affected by a large civil infrastructure?

“…When they are in a favourable habitat, the flight distances are lower (Bustamante 1997;Tella et al 1998;Catry et al 2013), and in our study the frequency of locations at greater distances from the nest is higher in the thermosolar power plant colony, with also greater distances than those of the individuals from the other colony (located in a natural landscape) before July 15, when they need more quantity of preys to feed the chicks. Coinciding with Vlachos et al (2015), we have not observed differences in the foraging areas and distances to the nest between sexes, although other studies have found a spatial segregation, with males foraging closer to the colony than females (Hernández-Pliego et al 2017).…”

Large birds travel farther in homogeneous environments

“…Previous work has examined species‐level differences in movement patterns, including differences in home‐range size (Haskell, Ritchie, & Olff, ) and migration distances/strategies (Alerstam, Hedenström, & Åkesson, ; La Sorte et al, ) based on species‐level traits (e.g., body size and diet). Some of the variation among individuals within the same species is probably attributable to sex, because males and females have different movement patterns during brood rearing (Hernández‐Pliego, Rodríguez, & Bustamante, ). In addition, feather moult (i.e., feathers being shed and regrown) may impact avian movements, including periods of flightlessness (e.g., cranes and waterfowl post‐breeding) and reduced aerodynamic performance of the wings (e.g., Falco peregrinus ; Flint & Meixell, ).…”

Analysis of movement recursions to detect reproductive events and estimate their fate in central place foragers

“…False positives were none or negligible for gulls and storks (0 and 2% respectively), but reached 50% for kestrels. This is likely explained by species-specific behavior: kestrels spend long stretches of time and consecutive days on a perch while scanning for prey or resting [37]. Distinguishing these patterns of attendance and revisitation from those of a nest might be challenging without applying restrictions based on seasonality and geographical area (for instance, breeding versus wintering range).…”

“…In this case, our inability to recognize the attempt as successful might have depended on behavioral differences between parents, whereby the male we were tracking might have interrupted parental care before the female did. This result highlights the importance of taking into account sex differences in breeding behavior, where that applies [37]. For example, in species exhibiting uniparental care, inference should only be based on the sex that carries out parental care [8].…”