Wintering areas predict age‐related breeding phenology in a migratory passerine bird

Abstract

Understanding connections between breeding, stopover and wintering grounds for long‐distance migratory birds can provide important insight into factors influencing demography and the strength of carry‐over effects among various periods of the annual cycle. Using previously described, multi‐isotope (δ13C, δ15N, δ2H) feather isoscapes for Africa, we identified the most probable wintering areas for house martins Delichon urbica breeding at Badajoz in southwestern Spain. We identified two most‐probable wintering areas differing in isotopic signature in west Africa. We found that the probability to winter in the isotopic cluster two was related to age and sex of individuals. Specifically, experienced males (i.e. two years or older) winter in the isotopic cluster two with a greater probability than experienced females, whereas first‐year females winter in the isotopic cluster two with a greater probability than first‐year males. In addition, wintering area was correlated with breeding phenology, with individuals wintering in the isotopic cluster two initiating their clutches earlier than those wintering in the isotopic cluster one. For birds wintering in the isotopic cluster two, there was no relationship between age and clutch initiation date. In contrast, young birds wintering in the isotopic cluster one initiated their clutches earlier than experienced birds wintering in this area. There was no significant correlation between wintering area and clutch size or the number of fledglings produced. We hypothesize that the relationship among social status, population density and winter habitat quality should be the most important driver of the carry‐over effect we found for this population.

Rainfall at African wintering grounds predicts age‐specific probability of haemosporidian infection in a migratory passerine bird

“…In contrast, young birds wintering in habitats with higher rainfall had a lower probability of becoming infected compared with young birds wintering in habitats with lower rainfall. Unlike previous studies in other bird species, we were also able to associate House Martins with specific wintering areas using assignment to isoscapes , L opez-Calder on et al 2017a, where we were better able to interpret climate regimes. For instance, Great Reed Warblers wintering in tropical Africa suffer a higher haemosporidian prevalence associated with water-stressed habitats (Yohannes et al 2008).…”

“…In addition, our results indicate that age-class is another source of variance to take into account in these kinds of studies. Unlike previous studies in other bird species, we were also able to associate House Martins with specific wintering areas using assignment to isoscapes , L opez-Calder on et al 2017a, where we were better able to interpret climate regimes.…”

“…Because previous studies have revealed the importance of age for haemosporidian infection and migratory ecology in House Martins (Marzal et al 2016, L opez-Calder on et al 2017a, we also tested for differences in the probability of blood infection and winter quarters according to ageclass. genera Haemoproteus, Plasmodium and Leucozytozoon).…”

“…As a proxy for winter origins and habitats used during moult, we used stable isotope (d 2 H, d 13 C and d 15 N) measurements from winter-grown feathers. Because previous studies have revealed the importance of age for haemosporidian infection and migratory ecology in House Martins (Marzal et al 2016, L opez-Calder on et al 2017a, we also tested for differences in the probability of blood infection and winter quarters according to ageclass. The few studies that have previously explored the relationship between feather stable isotope values and haemosporidian infection in birds have shown mixed results.…”

Environmental conditions during winter predict age- and sex-specific differences in reproductive success of a trans-Saharan migratory bird

“…In an ecological context, carry-over effects occur when the previous history and experience of an individual explains its current performance in a given situation 1 . Many studies of migratory birds have found that environmental conditions experienced during winter have carry-over effects in terms of subsequent body condition and breeding phenology 2 – 7 . However, few studies have found carry-over effects of environmental conditions from winter areas on final reproductive success 8 – 12 .…”