Using a common morphometric-based method to sex a migratory bird along its entire flyway despite geographical and temporal variations in body size and sexual size dimorphism

TY - JOUR

T1 - Using a common morphometric-based method to sex a migratory bird along its entire flyway despite geographical and temporal variations in body size and sexual size dimorphism

AU - Pagnon, Thomas

AU - Etchart, Léa

AU - Teixeira, Maria

AU - Dechaume-Moncharmont, François Xavier

AU - Hallgrimsson, Gunnar T.

AU - Hansen, Jannik

AU - Lang, Johannes

AU - Moreau, Jérôme

AU - Reneerkens, Jeroen

AU - Schmidt, Niels M.

AU - Soloviev, Mikhail

AU - ten Horn, Job

AU - Tomkovich, Pavel

AU - Wood, Andrew G.

AU - Yannic, Glenn

AU - Bollache, Loïc

AU - Gilg, Olivier

PY - 2024/10

Y1 - 2024/10

N2 - Sexing bird species with monomorphic plumage is generally challenging, and sexual size dimorphism (SSD) is often used to develop morphometric-based sexing tools, e.g., using discriminant functions. Within species, local selection pressures, age-related and season-related growth may, however, induce geographical and temporal variations in body size and SSD. Such variations may complicate the development of reliable morphometric-based sexing methods at a broad scale. We first investigated body size variations in a migratory shorebird species with wide breeding and wintering ranges, the Sanderling Calidris alba, within the two breeding populations (Greenland and Russia) and three staging/wintering populations (United Kingdom, Iceland and Mauritania), which belong to the same flyway. Then, for samples from each region, we tested whether site-specific (i.e., “regional”) functions performed better than functions developed for birds from the other sites (i.e., “foreign” functions) or than an overall (“flyway”) function that combined all sampled individuals. We found minor variations in SSD between regions, but significant differences in body size between sexes and regions. Females were larger than males and, for instance, breeders had longer wings than staging and wintering birds. Regional functions had similar sexing efficiency as any other functions applied to sample from each region, except for Western Africa where the regional function performed slightly better than some of the other functions. Furthermore, the flyway function developed after merging all subsamples had a similar efficiency than the regional functions, i.e., from 75.4% to 90% of correct sex assignment depending on the region. Given the small or lack of benefit in using regional functions, we conclude that the flyway function can be used reliably to sex Sanderlings measured at different sites, years or seasons within the East Atlantic flyway. Our results may help to develop global sexing function for other bird species.

AB - Sexing bird species with monomorphic plumage is generally challenging, and sexual size dimorphism (SSD) is often used to develop morphometric-based sexing tools, e.g., using discriminant functions. Within species, local selection pressures, age-related and season-related growth may, however, induce geographical and temporal variations in body size and SSD. Such variations may complicate the development of reliable morphometric-based sexing methods at a broad scale. We first investigated body size variations in a migratory shorebird species with wide breeding and wintering ranges, the Sanderling Calidris alba, within the two breeding populations (Greenland and Russia) and three staging/wintering populations (United Kingdom, Iceland and Mauritania), which belong to the same flyway. Then, for samples from each region, we tested whether site-specific (i.e., “regional”) functions performed better than functions developed for birds from the other sites (i.e., “foreign” functions) or than an overall (“flyway”) function that combined all sampled individuals. We found minor variations in SSD between regions, but significant differences in body size between sexes and regions. Females were larger than males and, for instance, breeders had longer wings than staging and wintering birds. Regional functions had similar sexing efficiency as any other functions applied to sample from each region, except for Western Africa where the regional function performed slightly better than some of the other functions. Furthermore, the flyway function developed after merging all subsamples had a similar efficiency than the regional functions, i.e., from 75.4% to 90% of correct sex assignment depending on the region. Given the small or lack of benefit in using regional functions, we conclude that the flyway function can be used reliably to sex Sanderlings measured at different sites, years or seasons within the East Atlantic flyway. Our results may help to develop global sexing function for other bird species.

KW - Discriminant function

KW - East Atlantic flyway

KW - Molecular sexing

KW - Sanderling

KW - Shorebird

UR - http://www.scopus.com/inward/record.url?scp=85192507174&partnerID=8YFLogxK

U2 - 10.1007/s10336-024-02178-9

DO - 10.1007/s10336-024-02178-9

M3 - Journal article

SN - 2193-7206

VL - 165

SP - 923

EP - 934

JO - Journal of Ornithology

JF - Journal of Ornithology

IS - 4

ER -