Migratory and resident waders differ in risk taking on the wintering grounds

Animals, including birds, have to optimize their escape strategies under the risk of predation. Level of risk-taking is often estimated as flight initiation distance (FID), which is assumed to reflect the trade-off between costs of escape and benefits of staying put. Despite costs and benefits of escape may change during the season, previous studies have focused mainly on breeding bird populations. Here, we focused on risk taking in migratory and resident populations of waders (Charadriiformes) at the wintering grounds in tropical Africa. Phylogenetically informed comparative analyses revealed significant correlation between starting distance, body mass and, marginally, reproductive effort and FID, but no correlation between flock size and FID in wintering waders. Interestingly, despite no differences in body mass, reproductive effort and flock size, FID significantly differed between migratory and resident wader species after controlling for the potential effect of confounding variables, with FID being shorter in resident species. This suggests that such differences in risk perception are linked to some other factors as, for instance, the level of familiarity of waders with local environments at their wintering grounds and previous experience with humans. Our results may have also implications for avian conservation of migratory species at wintering grounds.PM and TA were financially supported through the Czech Science Foundation [14–36098G]. Field research in Kenya (MH) was supported by ITMS [26110230119] and VEGA [1/0977/16].Peer Reviewe

Adjusting risk taking to the annual cycle of long-distance migratory birds

© The Author(s) 2018.Life-history theory predicts that current behaviour affects future reproduction, implying that animals should optimise their escape strategies to reflect fitness costs and benefits of premature escape. Both costs and benefits of escape may change temporally with important consequences for the evolution of escape strategies. Moreover, escape strategies of species may differ according to their positions on slow–fast pace of life gradients. We studied risk-taking in long-distance migratory animals, waders (Charadriiformes), during the annual cycle, i.e., breeding in Europe, stopover in the Middle East and wintering in tropical Africa. Phylogenetically informed comparative analyses revealed that risk-taking (measured as flight initiation distance, FID) changed significantly over the year, being lowest during breeding and peaking at stopover sites. Similarly, relationships between risk-taking and life-history traits changed among stages of the annual cycle. While risk-taking significantly decreased with increasing body mass during breeding, risk-taking–body mass relationship became marginally significant in winter and disappeared during migration. The positive trend of risk-taking along slow–fast pace of life gradient measured as adult survival was only found during breeding. The season-dependent relationships between risk-taking and life history traits suggest that migrating animals respond to fluctuating environments by adopting behavioural plasticity.Te study was fnancially supported by project OPV ITMS26110230119 and VEGA 1/0977/16. TA and PM were supported by Czech Science Foundation project (14–36098G). This paper is a contribution by MD to the thematic network REMEDINAL3-CM (S2013/ MAE-2719).Peer Reviewe