Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities

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, usi...

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Autores: Serrano Davies, Eva, Traba , Juan, Mougeot, François Robert, Arroyo Lopez, Beatriz
Tipo de recurso: artículo
Fecha de publicación:2023
País:España
Institución:Universidad de Castilla-La Mancha
Repositorio:RUIdeRA. Repositorio Institucional de la UCLM
OAI Identifier:oai:ruidera.uclm.es:10578/43200
Acceso en línea:https://hdl.handle.net/10578/43200
Access Level:acceso abierto
Palabra clave:Conservation
Endangered species
Female mortality
Steppe birds
Western Europe
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spelling Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalitiesSerrano Davies, EvaTraba , JuanMougeot, François RobertArroyo Lopez, BeatrizConservationEndangered speciesFemale mortalitySteppe birdsWestern EuropeAdult 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 achieveCambridge University Press202520252023info:eu-repo/semantics/articleapplication/pdfapplication/pdfhttps://hdl.handle.net/10578/43200reponame:RUIdeRA. Repositorio Institucional de la UCLMinstname:Universidad de Castilla-La ManchaInglésinfo:eu-repo/semantics/openAccessoai:ruidera.uclm.es:10578/432002026-05-27T07:36:41Z
dc.title.none.fl_str_mv Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
title Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
spellingShingle Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
Serrano Davies, Eva
Conservation
Endangered species
Female mortality
Steppe birds
Western Europe
title_short Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
title_full Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
title_fullStr Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
title_full_unstemmed Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
title_sort Biased adult sex ratios in Western Europe populations of Little Bustard (Tetrax tetrax) as a potential warning signal of unbalanced mortalities
dc.creator.none.fl_str_mv Serrano Davies, Eva
Traba , Juan
Mougeot, François Robert
Arroyo Lopez, Beatriz
author Serrano Davies, Eva
author_facet Serrano Davies, Eva
Traba , Juan
Mougeot, François Robert
Arroyo Lopez, Beatriz
author_role author
author2 Traba , Juan
Mougeot, François Robert
Arroyo Lopez, Beatriz
author2_role author
author
author
dc.subject.none.fl_str_mv Conservation
Endangered species
Female mortality
Steppe birds
Western Europe
topic Conservation
Endangered species
Female mortality
Steppe birds
Western Europe
description 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
publishDate 2023
dc.date.none.fl_str_mv 2023
2025
2025
dc.type.none.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/10578/43200
url https://hdl.handle.net/10578/43200
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Cambridge University Press
publisher.none.fl_str_mv Cambridge University Press
dc.source.none.fl_str_mv reponame:RUIdeRA. Repositorio Institucional de la UCLM
instname:Universidad de Castilla-La Mancha
instname_str Universidad de Castilla-La Mancha
reponame_str RUIdeRA. Repositorio Institucional de la UCLM
collection RUIdeRA. Repositorio Institucional de la UCLM
repository.name.fl_str_mv
repository.mail.fl_str_mv
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score 15.81155

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