2026-04-17T15:44:44Zhttps://recercat.cat/oai/request

oai:recercat.cat:10459.1/842932024-12-05T21:24:29Zcom_2072_3622col_2072_479130

Biased sex ratios in Western Europe populations of little bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities Serrano-Davies, Eva Traba, Juan Arroyo, Beatriz Mougeot, François Cuscó, Francesc Mañosa, Santi Bota, Gerard Faria, Nuno Villers, Alexandre Casas, Fabián Attie, Carole Devoucoux, Pierrick Bretagnolle, Vincent Morales, Manuel B. Female mortality Conservation Endangered species Steppe birds Western Europe Adult sex ratios (ASRs) have proved to correlate with population trends, which make them potential useful indicators of a species’ population trajectory and conservation status. We analysed ASRs and proportion of juveniles in flocks of an endangered steppe bird, the Little Bustard Tetrax tetrax, using surveys made during the non-breeding period in seven areas within its Western European range (one in Portugal, four in Spain, and two in France). We found overall male-biased ASRs, as all the seven surveyed areas showed a male-biased ASR mean value. Five areas were below the threshold median value (female sex ratio = 0.4) considered to be consistent with an increased probability of extinction, according to earlier population viability analyses for the species. We also found a significant positive correlation between female ratio and the proportion of young individuals in the non-breeding flocks surveyed. Our results (strongly male-biased ASRs) support the hypothesis that the viability of Little Bustard populations in Western Europe is threatened by an excess of female mortality, something that should be quantified in the future, and emphasise the value of monitoring sex ratio as a population viability indicator in species where monitoring survival is difficult to achieve. This paper is a contribution to the REMEDINAL 3 (S2013/MAE-2719) network which funded a post-doc contract for ESD. It also contributes to the Excellence Network REMEDINAL 3CM (S2013/ MAE2719), supported by Comunidad de Madrid. We thank all the field workers that collaborated in this study. Thanks to Ricardo Montero from Extremadura Birding who provided us with a Little Bustard winter flock video record. We are grateful to Julia Gómez-Catasús for her help with the bootstrapping analysis. This study was carried out with no funds from the Spanish Ministry of Science and Innovation. 2024-12-05T21:24:29Z 2024-12-05T21:24:29Z 2024-12-05T21:24:29Z 2022-11-22T13:24:25Z 2022-11-22T13:24:25Z 2022 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion http://hdl.handle.net/10459.1/84293 Reproducció del document publicat a https://doi.org/10.1017/S0959270922000430 Bird Conservation International, 2022, p. 1-8 cc-by, (c) Serrano-Davies et al., 2022 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Cambridge University Press