Diet and provisioning rate differ predictably between dispersing and philopatric pied flycatchers

• Published in: Behavioral ecology Vol. 30; no. 1; pp. 114 - 124
• Main Authors: Nicolaus, Marion, Barrault, Solange C Y, Both, Christiaan
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press 04.03.2019
• Subjects: dispersal syndrome; foraging behavior; animal personality; niche partitioning; diet specialization; provisioning rates
• ISSN: 1045-2249; 1465-7279
• DOI: 10.1093/beheco/ary152

Dispersers should express different foraging or social behaviors than nondispersers to thrive in unfamiliar habitats. In pied flycatchers (Ficedula hypoleuca), “naive” dispersers (immigrants) had a more generalist diet and higher feeding rates compared with philopatric birds, but we found no difference in level of aggression. Males with more generalist diet fledged more young. This suggests that learning or early imprinting affects individual food and settlement choices and that dispersers adopt different life-history strategies. Abstract Dispersal is an essential process for most animal populations to persist in changing environments. Dispersers are often a nonrandom sample of the population, and differ consistently from nondispersers in a suite of correlated phenotypic traits (“dispersal syndromes”). This phenotypic integration is thought to be adaptive. Here, we investigate whether dispersal tendency of individual pied flycatchers (Ficedula hypoleuca) covaries with a set of repeatable behaviors that should confer advantages for surviving and reproducing in novel environments. We specifically focus on the link between dispersal, foraging behavior, and aggressiveness because selection on foraging tactics or social behaviors likely differs between individuals staying in familiar or dispersing to novel environments. Using repeated measures of nestling provisioning data of pied flycatcher parents in 1 year, we tested if immigrants and philopatric individuals (local recruits and experienced breeders) differed in diet specialization, provisioning rates, levels of aggression, and reproductive success. Results show that individuals differed consistently in their foraging behavior, with immigrants having a more generalist diet and higher feeding rates than philopatric birds, but not in aggressiveness. More generalist males fledged more young. Our findings suggest that prior local knowledge facilitates diet specialization, and that more generalist diets could be adaptive for immigrants breeding in unknown environments. Aggressiveness was not part of the dispersal syndrome in our population, perhaps because high aggression levels are too costly to maintain in high density populations. Understanding the proximate causes and ultimate consequences of variation in dispersal syndromes requires now experimental manipulations of individual dispersal decisions.