1 research outputs found
Multievent capture-recapture analysis reveals individual foraging specialisation in a generalist species
Populations of species typically considered trophic generalists may include
specialized individuals consistently feeding on certain resources. Optimal foraging theory
states that individuals should feed on those resources most valuable to them. This, however,
may vary according to individual differences in detecting or processing resources, different
optimization criteria, and competitive abilities. White Storks (Ciconia ciconia) are trophic
generalists at the population level. Their European population recovery has been attributed to
increased wintering in southern Europe (rather than Africa) where they feed upon new
anthropogenic food subsidies: predictable dumps and less predictable and more difficult to
detect, but abundant, invasive Procambarus clarkii crayfishes in ricefields. We studied the
foraging strategies of resident and wintering storks in southwestern Spain in ricefields and
dumps, predicting that more experience in the study area (residents vs. immigrants, old vs.
young) would increase ricefield specialization. We developed the first multi-event capture–
recapture model to evaluate behavioral consistency, analyzing 3042 observations of 1684
banded storks. There were more specialists among residents (72%) than immigrants (40%). All
resident specialists foraged in ricefields, and ricefield use increased with individual age. In
contrast, some immigrants specialized on either dumps (24%) or ricefields (16%), but the
majority were generalists (60%). Our results provide empirical evidence of high individual
foraging consistency within a generalist species and a differential resource selection by
individuals of different ages and origins, probably related to their previous experience in the
foraging area. Thus, future changes in food resource availability at either of the two
anthropogenic subsidies (ricefields or dumps) may differentially impact individuals of different
ages and origins making up the wintering population. The use of multi-event capture–
recapture modeling has proven useful for studying interindividual variability in behaviorPeer reviewe