Affinity for natal environments by dispersers impacts reproduction and explains geographical structure of a highly mobile bird

Abstract

Understanding dispersal and habitat selection behaviours is central to many problems in ecology, evolution and conservation. One factor often hypothesized to influence habitat selection by dispersers is the natal environment experienced by juveniles. Nonetheless, evidence for the effect of natal environment on dispersing, wild vertebrates remains limited. Using 18 years of nesting and mark-resight data across an entire North American geographical range of an endangered bird, the snail kite (Rostrhamus sociabilis), we tested for natal effects on breeding-site selection by dispersers and its consequences for reproductive success and population structure. Dispersing snail kites were more likely to nest in wetlands of the same habitat type (lacustrine or palustrine) as their natal wetland, independent of dispersal distance, but this preference declined with age and if individuals were born during droughts. Importantly, dispersing kites that bred in natal-like habitats had lower nest success and productivity than kites that did not. These behaviours help explain recently described population connectivity and spatial structure across their geographical range and reveal that assortative breeding is occurring, where birds are more likely to breed with individuals born in the same wetland type as their natal habitat. Natal environments can thus have long-term and large-scale effects on populations in nature, even in highly mobile animals.

Ecological traps: current evidence and future directions

“…However, recent empirical work demonstrates that animals that select natal-like habitats can have compromised fitness [28,29], which could exacerbate the effects of traps [10]. Dispersers in poor physiological condition or under time constraints may become less choosy or more likely to choose sub-optimal habitats in general [45], but the degree to which this results in ecological traps has not been explored.…”

Consistent scaling of population structure across landscapes despite intraspecific variation in movement and connectivity

“…; Fletcher et al . ), and including self‐loops in modularity analyses would shift the emphasis from isolating mesoscale structure among wetlands to primarily identifying wetlands where high site fidelity occurred, which was not of interest here (but see Table ). We created six adjacency matrices based on movement types that varied by individual trait (age and sex) and time interval (annual, seasonal, and within‐breeding season movements) (Table ) (Reichert et al .…”

Experimental Test of Preferences for an Invasive Prey by an Endangered Predator: Implications for Conservation

“…K is the number of parameters in the model, LL is the model likelihood, AICc is Akaike’s Information Criterion adjusted for small sample size, Δ AIC is the difference in AICc from one model to the best ranked model and AICc Weight is a normalized representation of the model likelihoods so that they are treated as relative probabilities for comparison [41]. …”

“…This allowed us to understand variability in preference through multiple choices, which would imply that the first choice might be exploratory rather than preferential. Models were evaluated with Akaike’s Information Criterion accounting for small sample size (AICc) and AICc weights [41]. The models that had the lowest AICc value and the highest AICc weight were considered to be top performing models [41].…”

“…Models were evaluated with Akaike’s Information Criterion accounting for small sample size (AICc) and AICc weights [41]. The models that had the lowest AICc value and the highest AICc weight were considered to be top performing models [41]. …”