Abstract
Breeding dispersal is a key process of population structure and dynamics and is often triggered by an individual's breeding failure. In both colonial and territorial birds, reproductive success of conspecifics (RSc) can also lead individuals to change breeding sites after a failure on a site. Yet, few studies have simultaneously investigated the independent contribution of individual reproductive success (RSi) and of RSc on dispersal decision. Here, we develop a modeling framework to disentangle the effects of RSi and RSc on demographic parameters, while accounting for imperfect individual detection and other confounding factors such as age or dispersal behavior in the previous year. Using a 10‐year capture–recapture dataset composed of 1,595 banded tree swallows, we assessed the effects of nonmanipulated RSi and RSc on female breeding dispersal in this semicolonial passerine. Dispersal was strongly driven by RSi, but not by RSc. Unsuccessful females were 9.5–2.5 times more likely to disperse than successful ones, depending if they had dispersed or not in the previous year, respectively. Unsuccessful females were also three times less likely to be detected than successful ones. Contrary to theoretical and empirical studies, RSc did not drive the decision to disperse but influenced the selection of the following breeding site once dispersal had been initiated. Because detection of individuals was driven by RSi, which was positively correlated to RSc, assuming a perfect detection as in previous studies may have lead us to conclude that RSc affected dispersal patterns, yet our approach corrected for this bias. Overall, our results suggest that the value and use of RSc as public information to guide dispersal decisions are likely dictated by multiple ecological determinants, such as landscape structure and extent, if this cue is indeed used.
Highlights
Breeding dispersal, the movement between subsequent breeding sites, plays a key role in population structure and dynamics as well as evolution (Clobert, Danchin, Nichols, & Dhondt, 2001)
We considered a “memory” effect whereby individuals dispersing in the previous year may show a higher dispersal probability than individuals faithful to their breeding site at t – 1, as previously shown to occur in tree swallows from this system (Lagrange et al, 2014)
We found no evidence to suggest that female birds modulate their decision to disperse on the basis of the breeding success of surrounding conspecifics (RSc)
Summary
The movement between subsequent breeding sites, plays a key role in population structure and dynamics as well as evolution (Clobert, Danchin, Nichols, & Dhondt, 2001) This behavior is inherent to habitat selection, which can strongly determine the survival and reproductive success of individuals (Bowler & Benton, 2005). Our second objective was to include the potential effect of RSc on the probability to disperse To tackle these objectives, we adapted a multievent capture–recapture model (Lagrange, Pradel, Bélisle, & Gimenez, 2014) to quantify the independent effects of RSi and RSc on the decision to disperse in female tree swallows while accounting for imperfect detection. We aimed to test the prediction that the likelihood of dispersal increases as RSi decreases, especially at low RSc, and assess the potential of RSc to override the effect of RSi on dispersal decisions as observed in Danchin et al (1998)
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