Sex‐biased breeding dispersal is predicted by social environment in birds

Abstract

Sex‐biased dispersal is common in vertebrates, although the ecological and evolutionary causes of sex differences in dispersal are debated. Here, we investigate sex differences in both natal and breeding dispersal distances using a large dataset on birds including 86 species from 41 families. Using phylogenetic comparative analyses, we investigate whether sex‐biased natal and breeding dispersal are associated with sexual selection, parental sex roles, adult sex ratio (ASR), or adult mortality. We show that neither the intensity of sexual selection, nor the extent of sex bias in parental care was associated with sex‐biased natal or breeding dispersal. However, breeding dispersal was related to the social environment since male‐biased ASRs were associated with female‐biased breeding dispersal. Male‐biased ASRs were associated with female‐biased breeding dispersal. Sex bias in adult mortality was not consistently related to sex‐biased breeding dispersal. These results may indicate that the rare sex has a stronger tendency to disperse in order to find new mating opportunities. Alternatively, higher mortality of the more dispersive sex could account for biased ASRs, although our results do not give a strong support to this explanation. Whichever is the case, our findings improve our understanding of the causes and consequences of sex‐biased dispersal. Since the direction of causality is not yet known, we call for future studies to identify the causal relationships linking mortality, dispersal, and ASR.

Successful breeding predicts divorce in plovers

“…For example, many mammals are socially polygynous, males do not participate in parental care, females rely on home ranges with resources to successfully rear offspring, therefore, male-biased dispersal is expected. Whereas in birds, which are typically socially monogamous, males demonstrate territorial defence behaviour because high quality breeding sites provide good resources and opportunities for successful breeding, thus reducing male’s tendency to move large distance between breeding attempts 86 – 89 . Our result follows the general pattern of female-biased breeding dispersal observed in most bird species including shorebirds 90 , 91 .…”

Why we should care about movements: Using spatially explicit integrated population models to assess habitat source–sink dynamics

“…This would lead to a stronger underestimation of true survival for females than for males even after accounting for local movements. In line with this hypothesis, breeding and natal dispersal movements are typically female biased in birds (Greenwood & Harvey, 1982;Végvári et al, 2018). As almost all empirical data come from limited study areas, it remains challenging to know how well distances estimated from movements within study areas reflect movements out of the study areas.…”

A behavioural trait displayed in an artificial novel environment correlates with dispersal in a wild bird

“…On a smaller scale, we determined breeding dispersal distance for the birds that had bred in our study plots in the previous year or in the subsequent year ( N = 225) relative to the year of behavioural measurements. Breeding dispersal distance is defined as the distance between the former breeding area and a new breeding site of the animal (Belliure, Sorci, Moller, & Clobert, ; Végvári et al, ), and it is also commonly used in migratory species (Paradis, Baillie, Sutherland, & Gregory, ; Pärt, ). To estimate breeding dispersal distance, we used the GPS coordinates of the respective nest boxes and calculated their aerial distance.…”