Geographical variation, sex and age in Great Bittern <i>Botaurus stellaris</i> using coloration and morphometrics

Dmitrenok, Marina; Puglisi, Luca; Demongin, Laurent; Gilbert, Gillian; Polak, Marcin; Bretagnolle, Vincent

doi:10.1111/j.1474-919x.2006.00592.x

Cited by 10 publications

(5 citation statements)

References 15 publications

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“…A wide breeding range, such as that of the Little Stint, often results in a geographical variation in biometrics ( Zwarts et al, 1996 ; Dmitrenok et al, 2007 ), which might distort a discriminant function analysis. We do not expect such differences in our study because Little Stints are an opportunistic species that show no natal philopatry or breeding-site fidelity and breed wherever they find favourable environmental conditions ( Hildén, 1983 ; Underhill et al, 1993 ; Tomkovich & Soloviev, 1994 ).…”

Section: Discussionmentioning

confidence: 99%

Sexual dimorphism in adult Little Stints (Calidris minuta) revealed by DNA sexing and discriminant analysis

Niemc

Remisiewicz

Avni³

et al. 2018

PeerJ

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BackgroundThe sex of an individual organism plays such an important role in its life cycle that researchers must know a bird’s sex to interpret key aspects of its biology. The sexes of dimorphic species can be easily distinguished, but sexing monomorphic bird species often requires expensive and time-consuming molecular methods. The Little Stint (Calidris minuta) is a numerous species, monomorphic in plumage but showing a small degree of reversed sexual size dimorphism. Females are larger than males but the ranges of their measurements overlap, making Little Stints difficult to sex in the field. Our aim was to develop reliable sexing criteria for Little Stints in different stages of primary moult during their stay on the non-breeding grounds in South Africa using DNA-sexed individuals and discriminant function analysis.MethodsWe caught 348 adult Little Stints in 2008–2016 on their non-breeding grounds at Barberspan Bird Sanctuary. To molecularly identify the birds’ sex we used P2/P8 primers and DNA isolated from blood samples collected in the field. We used Storer’s dimorphism index to assess the degree of sexual size dimorphism. Then we divided our sample into two groups: before or during and after primary moult. For each group we developed two functions: one using wing length only and the other a combination of morphometric features including wing, tarsus and total head length. Then we used a stepwise procedure to check which combination of measurements best discriminated sexes. To validate our result we used a jack-knife cross-validation procedure and Cohen-kappa statistics.ResultsAll the morphometric features we measured were bigger in DNA-sexed females than in males. Birds with fresh primaries had on average 2.3 mm longer wings than those with worn primaries. A discriminant function using wing length (D1) correctly sexed 78.8% of individuals before moult, and a stepwise analysis showed that a combination of wing length and tarsus (D2) correctly identified the sex of 82.7% of these birds. For birds with freshly moulted primaries a function using wing length (D3) correctly classified 83.4% of the individuals, and a stepwise analysis revealed that wing and total head length (D4) classified 84.7%.DiscussionSexual size differences in Little Stints might be linked to their phylogenetics and breeding biology. Females are bigger, which increases their fecundity; males are smaller, which increases their manoeuverability during display flights and hence their mating success. Little Stints show an extreme lack of breeding site fidelity so we did not expect a geographical cline in their biometrics. Sexing criteria available for Little Stints in the literature were developed using museum specimens, which often shrink, leading to misclassification of live birds. The sexing criteria we developed can be used for studies on Little Stints at their non-breeding grounds and on past data, but should be applied cautiously because of the overlapping ranges.

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Section: Discussionmentioning

confidence: 99%

Sexual dimorphism in adult Little Stints (Calidris minuta) revealed by DNA sexing and discriminant analysis

Niemc

Remisiewicz

Avni³

et al. 2018

PeerJ

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show abstract

“…A wide breeding range, such as that of the Little Stint, often results in a geographical variation in biometrics (Zwarts et al, 1996;Dmitrenok et al, 2007), which might distort a discriminant function analysis. We do not expect such differences in our study because Little Stints are an opportunistic species that show no natal philopatry or breeding-site fidelity and breed wherever they find favourable environmental conditions (Hildén, 1983; PeerJ reviewing PDF | (2018:02:24980:1:1:NEW 28 Jun 2018)…”

Section: Discussionmentioning

confidence: 99%

Peer Review #3 of "Sexual dimorphism in adult Little Stints (Calidris minuta) revealed by DNA sexing and discriminant analysis (v0.1)"

Scherer¹

2018

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Background. The sex of an individual organism plays such an important role in its life cycle that researchers must know a bird's sex to interpret key aspects of its biology. Sexes of dimorphic species can be easily distinguished, but sexing monomorphic bird species often requires expensive and timeconsuming molecular methods. The Little Stint (Calidris minuta) is a numerous species, monomorphic in plumage but showing a small degree of reversed sexual size dimorphism. Females are larger than males but the ranges of their measurements overlap, making Little Stints difficult to sex in the field. Our aim was to develop reliable sexing criteria for Little Stints in different stages of primary moult during their stay on the non-breeding grounds in South Africa using DNA-sexed individuals and discriminant function analysis. Methods. We caught 348 adult Little Stints in 2008-2016 on their non-breeding grounds at Barberspan Bird Sanctuary. To molecularly identify the birds' sex we used P2/P8 primers and DNA isolated from blood samples collected in the field. We used Storer's dimorphism index to assess the degree of sexual size dimorphism. Then we divided our sample into two groups: before or during and after primary moult. For each group we developed two functions: one using wing length only and the other a combination of morphometric features including wing, tarsus and total head length. Then we used a stepwise procedure to check which combination of measurements best discriminated sexes. To validate our result we used a jack-knife cross-validation procedure and Cohen-kappa statistics. Results. All the morphometric features we measured were bigger in DNA-sexed females than in males. Birds with fresh primaries had on average 2.3 mm longer wings than those with worn primaries. A discriminant function using wing length (D 1) correctly sexed 78.8% of individuals before moult, and a stepwise analysis showed that a combination of wing length and tarsus (D 2) correctly identified the sex of 82.7% of these birds. For birds with freshly moulted primaries a function using wing length (D 3) correctly classified 83.4% of the individuals, and a stepwise analysis revealed that wing and total head length (D 4) classified 84.7%. Discussion. Sexual size differences in Little Stints might be linked to their phylogenetics and breeding biology. Females are bigger, which increases their fecundity; males are smaller, which increases their manoeuverability during display flights and hence their mating success. Little Stints show an extreme lack of breeding site fidelity so we did not expect a geographical cline in their biometrics. Sexing criteria available for Little Stints in the literature were developed using museum specimens, which often shrink, leading to misclassification of live birds. The sexing criteria we developed can be used for studies on Little Stints at their non-breeding grounds and on past data, but should be applied cautiously because of the overlapping ranges.

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“…Eurasian Bitterns Botaurus stellaris (Bittern from hereon) are highly sexually dimorphic. Males are almost twice as heavy as females (Cramp & Simmons 1977), with occasional overlap in mass during the nonbreeding season (Dmitrenok et al 2007). Bitterns breed across temperate Atlantic and Mediterranean as well as boreal climates with colder winters from the United Kingdom (UK) in the west to Japan in the east (Cramp & Simmons 1977, Voisin 1991, White et al 2006.…”

Section: Sex-related Migration Distances In the Dimorphic Eurasianmentioning

confidence: 99%

Sex-Related Migration Distances in the Dimorphic Eurasian Bittern Botaurus stellaris Breeding in the Netherlands

Winden¹,

Hogeweg²,

Shamoun‐Baranes

et al. 2020

Ardea

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In many bird species intraspecific variation in migration strategies is related to sex or size. The Eurasian Bittern Botaurus stellaris is a sexually size-dimorphic heron species with a vast breeding and wintering range spanning a range of climates. Ringing data show that Bitterns from northern populations migrate westwards or southwards over thousands of kilometres, while Bitterns from southern or temperate breeding areas migrate much shorter distances or remain resident. So far, any differences in the migrations of males and females have remained unstudied. In temperate climates, relatively benign winters alternate with the occasional harsh winter, and under these conditions, males as the larger sex might take the risk to stay rather than show seasonal migration. In the years 2010-2012 we equipped three females and three males from breeding areas in The Netherlands with a tracking device, recording their movements over periods of 2-5 years. All three males and one female stayed within or near the breeding area during the non-breeding season, but two females moved to distant wintering sites. One female migrated 4900 km to The Gambia providing the first direct evidence for trans-Saharan migration in this species. Another female migrated 700 km to winter in Devon, UK, for five consecutive years. The Bitterns were site-faithful to their breeding area and, mostly, to their wintering areas as well, although one male and one female progressively wintered closer to the breeding area in three successive years. Our results suggest that larger males from The Netherlands, a breeding area with fluctuating winter conditions, are predominantly resident, while the females are partial migrants with individually different and flexible strategies.

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Geographical variation, sex and age in Great Bittern Botaurus stellaris using coloration and morphometrics

Cited by 10 publications

References 15 publications

Sexual dimorphism in adult Little Stints (Calidris minuta) revealed by DNA sexing and discriminant analysis

Sexual dimorphism in adult Little Stints (Calidris minuta) revealed by DNA sexing and discriminant analysis

Peer Review #3 of "Sexual dimorphism in adult Little Stints (Calidris minuta) revealed by DNA sexing and discriminant analysis (v0.1)"

Sex-Related Migration Distances in the Dimorphic Eurasian Bittern Botaurus stellaris Breeding in the Netherlands

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