Conditions at autumn stopover sites affect survival of a migratory passerine

Abstract

Weather is an important factor affecting many aspects of avian ecology, yet its importance for survival during various periods of the avian annual cycle has received relatively little attention and remains poorly understood. We have investigated the effect of weather conditions at the breeding and wintering grounds and during migration on the survival probability of Eurasian Reed Warblers Acrocephalus scirpaceus, a long-distance Palaearctic-African migrant species. We found that annual survival was significantly affected by precipitation at the autumn stopover sites in Spain and Morocco, where Reed Warblers accumulate energy reserves prior to crossing the Sahara desert: low rainfall was associated with decreased survival. We suggest that arid conditions at these crucial stopover sites may cause limitations in food availability, prevent proper refueling and hence result in lower survival.Survival estimates were not related to weather conditions in Africa during the bird wintering period or the preceding wet season. Likewise, meteorological conditions at the breeding area did not influence survival. Survival estimates for males and females did not differ, although recapture probability was significantly lower for females than for males. Our results indicate that weather significantly influences Reed Warbler survival, although its effect may vary for different stages of the annual cycle. Our findings suggest that marked climatic changes occurring along migratory routes, in particular at important stopover sites, may have far-reaching consequences on bird survival and population size.

Disentangling the effects of environmental conditions on wintering and breeding grounds on age‐specific survival rates in a trans‐Saharan migratory raptor

“…Integrating all phases of the annual cycle, and potential effects associated with the sequential distribution of individuals across time and space, is likely to improve our understanding of population dynamics (Ratikainen et al 2008, van de Pol et al 2010. Studies trying to disentangle the relative contribution of breeding and wintering conditions on survival of migratory populations remain rare (Cowley and Siriwardena 2005, Schaub et al 2005, Grande et al 2009, Halupka et al 2017) and, moreover, do not investigate the potential interaction between successive seasons. Indeed, conditions in one area or season could affect the ability of individuals, not only to reproduce (i.e.…”

Automated telemetry reveals staging behavior in a declining migratory passerine

“…Extrinsic environmental factors such as weather and geography also influence stopover dynamics. For instance, favorable wind conditions influence departure time in some species (e.g., Mitchell et al 2015, Dossman et al 2016, and rainfall may drive food availability, and therefore refueling rates, thus influencing stopover duration and survival (Halupka et al 2017). Individual stopover duration is largely determined by the interplay of these intrinsic and extrinsic factors, as a bird's behavior on stopover will depend on its geographic location, environmental conditions, and internal drivers (Cohen et al 2014, Deppe et al 2015.…”

Analysis of Bird Flyways in 3D

“…Besides the itinerary chosen by the birds, migration is affected by nutritional needs [6] and other factors such as weather conditions [32], the place of origin and destination [33], and the visibility, especially in the alpine environment. We tested whether there were routes along which birds can see at greater distances, and if there are visible stopover places.…”