Abstract
Natal or prebreeding dispersal is a key driver of the functioning, dynamics, and evolution of populations. Conditions experienced by individuals during development, that is, rearing conditions, may have serious consequences for the multiple components that shape natal dispersal processes. Rearing conditions vary as a result of differences in parental and environmental quality, and it has been shown that favorable rearing conditions are beneficial for individuals throughout their lives. However, the long‐term consequences of rearing conditions on natal dispersal are still not fully understood in long‐lived birds. In this study, we aim to test the following hypotheses to address the relationship between rearing conditions and certain components of the natal dispersal process in Bonelli’s eagle (Aquila fasciata): (1) The body condition of nestlings depends on the quality of the territory and/or breeders; and (2) the survival until recruitment, (3) the age of recruitment, and (4) the natal dispersal distance (NDD) all depend on rearing conditions. As expected, nestlings reared in territories with high past productivity of chicks had better body condition, which indicates that both body condition and past productivity reflect the rearing conditions under which chicks are raised. In addition, chicks raised in territories with high past productivity and with good body condition had greater chances of surviving until recruitment. Furthermore, birds that have better condition recruit earlier, and males recruit at a younger age than females. At last, although females in good body condition exhibited higher NDD when they recruited at younger ages, this pattern was not observed in either older females or males. Overall, this study provides evidence that rearing conditions have important long‐term consequences in long‐lived birds. On the basis of our results, we advocate that conservation managers work actively in the promotion of actions aimed at improving the rearing conditions under which individuals develop in threatened populations.
Highlights
Natal dispersal is a key driver of the functioning, dynamics, and evolution of populations and metapopulations (Clobert, Baguette, Benton, & Bullock, 2012; Debeffe et al, 2012; Dobson, 2012; Greenwood & Harvey, 1982)
Less is known about the mid- and long-term effects of rearing conditions on long-lived species (Szostek & Becker, 2015), which include the complex set of processes that, together, conform natal dispersal, such as the probability of surviving until recruitment, that is, the entry of prebreeding birds into the breeding portion of the population (Green & Cockburn, 2001; Hernández-Matías et al, 2010), the age at which individuals recruit (Acker et al, 2018; Grande et al, 2009; Hernández-Matías, Real, Pradel, Ravayrol, Vincent-Martin, 2011; Kokko & Sutherland, 1998), and the distance from the place of birth to the recruitment site, the so-called natal dispersal distance (NDD) (Rémy et al, 2011; Stamps, 2006)
We study whether natal dispersal distance depends on rearing conditions and test two further hypotheses
Summary
Natal dispersal is a key driver of the functioning, dynamics, and evolution of populations and metapopulations (Clobert, Baguette, Benton, & Bullock, 2012; Debeffe et al, 2012; Dobson, 2012; Greenwood & Harvey, 1982). Less is known about the mid- and long-term effects of rearing conditions on long-lived species (Szostek & Becker, 2015), which include the complex set of processes that, together, conform natal dispersal, such as the probability of surviving until recruitment, that is, the entry of prebreeding birds into the breeding portion of the population (Green & Cockburn, 2001; Hernández-Matías et al, 2010), the age at which individuals recruit (Acker et al, 2018; Grande et al, 2009; Hernández-Matías, Real, Pradel, Ravayrol, Vincent-Martin, 2011; Kokko & Sutherland, 1998), and the distance from the place of birth to the recruitment site, the so-called natal dispersal distance (NDD) (Rémy et al, 2011; Stamps, 2006) This gap in our knowledge is understandable given that effects of rearing conditions are less pronounced during middle and late life stages (Van De Pol et al, 2006). Hypothesis 6 assumes that natal dispersal can produce net benefits including the avoidance of inbreeding and the reduction of competition for resources and mates and, we predict that individuals in better body condition recruit farther from their natal territories
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