Differential migration of the sexes cannot be explained by the body size hypothesis in Teal

Guillemain, Matthieu; Hearn, Richard D.; King, Roy; Gauthier‐Clerc, Michel; Simon, Géraldine; Caizergues, Alain

doi:10.1007/s10336-009-0375-5

Cited by 17 publications

(26 citation statements)

References 26 publications

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“…Voelker 2001;O'Hara et al 2006). Such a hypothetical link between wing length and migration distance was not supported by earlier analyses in Teal (Guillemain et al 2009), suggesting that wing length may be a more valid proxy for body size at the population level in this species than in other ones. Furthermore, in another wintering population of Teal, Green et al (2001) found that wing length and tarsus length (another measure frequently taken during ringing programmes) had similar correlations with body mass, suggesting that they are equally good measures of structural size.…”

Section: Methodsmentioning

confidence: 44%

Individual quality persists between years: individuals retain body condition from one winter to the next in Teal

et al. 2013

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Few studies have considered how body condition changes over time in individual birds, and most of these concerned long-lived breeding birds. We used a large database of Common Teal Anas crecca ringed and recaptured while wintering in the Camargue to study interannual persistence in wing length and body condition. Winter body condition may be a major determinant of survival during that season, and may further be related to breeding success. Indices of condition were compared for individual Teal between the moments of ringing and of recapture the following winter, analyzing each sex and age class (adult or juvenile) separately. Wing length was highly repeatable between years, though some limited annual variation was also recorded in adult males. Using scaled mass index as an index of body condition, we observed that condition at ringing was the strongest predictor of body condition at recapture for males and juvenile females, although inter-and intra-annual variation was also significant in most cases. The value of the slope for the relationship between individual body condition indices at ringing and recapture did not differ from 1 for males and for adults, whereas, for juvenile females, the slope was significantly greater than 1, indicating that individual differences in condition became more exaggerated over time. When analyses were repeated using crude body mass instead of a condition index, results were generally similar. Birds recaptured the following winter had a greater body condition at ringing that those that were not recaptured, supporting the hypothesis of a link between winter body condition and return probability. Our results demonstrate the importance of a head start in Teal, given persistent effects of obtaining better condition in the first winter, and suggest specific age and sex effects. They also underline the value of condition indices as a long-term predictor of individual quality in birds, even during the non-breeding season and for such a relatively short-lived species.Keywords Scaled mass index Á Inter-annual changes Á Body size Á Fitness Á Inter-annual persistence Zusammenfassung Individuelle Qualität bleibt von Jahr zu Jahr bestehen: Krickenten behalten ihre individuelle Körperkondition von einem Winter zum nächsten bei Es gibt nur wenige Studien zu zeitlichen Veränderungen der Körperkondition von Vogelindividuen; die meisten von diesen Untersuchungen betreffen zudem langlebige Vogelarten zur Brutzeit. Anhand einer großen Datenmenge von Krickenten Anas crecca, die in ihrem Winterquartier in der Camargue beringt und wiedergefangen wurden, untersuchten wir die Persistenz von Flügellänge und Körperkondition von einem Jahr zum anderen. Die winterliche Körperkon-dition kann einen Hauptüberlebensfaktor zu dieser Jahreszeit darstellen und darüber hinaus mit dem Bruterfolg

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Section: Methodsmentioning

confidence: 44%

Individual quality persists between years: individuals retain body condition from one winter to the next in Teal

et al. 2013

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“…Boyd et al 1975), so declines cannot be attributed to gradual moult of wing feathers in first-years. Differential migration of the age-classes (sensu Cristol et al 1999) cannot be responsible, because analysis of ringing data detected no such difference in average wintering latitude between adults and first-year birds (despite differences between sexes; Guillemain et al 2009a). Age-ratios can also be biased if one of the age-classes gradually becomes less likely to be represented in the sample.…”

Section: Discussionmentioning

confidence: 96%

“…This is unlikely here, since the average age-ratio of ca. 45,000 Teal ringed in Camargue, Southern France and at Abberton Reservoir, Essex, UK, did not differ significantly (Guillemain et al 2009a), though the numerous exchanges of birds between these two areas suggest they belong to the same vast population (Guillemain et al 2005). Secondly, changes in age-ratios along the flyway may not reflect the gradual depletion of the juvenile part of the population if survival of these first-year birds gradually improves, especially if they learn to avoid hunters.…”

Section: Wing Collectionmentioning

confidence: 90%

How many juvenile Teal Anas crecca reach the wintering grounds? Flyway-scale survival rate inferred from wing age-ratios

Guillemain

Bertout²,

Christensen

et al. 2009

J Ornithol

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Autumn postnuptial migration is critical in the dabbling duck annual cycle, when first-year birds in particular suffer high losses to natural and hunting mortality. Mortality rates in this age-class are generally unknown in Europe where winter ringing predominates. We used data from large-scale wing collections from hunters in Finland, Denmark and France to test the prediction that juvenile proportions among killed Teal (Anas crecca) would decline with distance along the flyway. As expected, this proportion decreased from 89% in Northern Finland to 58% in Western France. Potential biases linked with age determination from the wings, differential migration of age-classes, relative susceptibility to different forms hunting and gradual improvement of juvenile survival as they learn to avoid hunters could not explain the observed decline of juveniles in the shot population. This pattern was therefore considered to be genuine, the result of the cumulative depletion of first-years along the flyway, likely through hunting. On this assumption, combined with known adult monthly survival rates during August-November (94.2%), monthly juvenile survival rate was estimated at 52.8%, i.e. 14.7% (range 13.9-15.4% based on extreme values of adult survival) amongst Scandinavian juveniles reaching wintering quarters in Western France. Despite lack of precision in such estimates based on relative proportions, there is little doubt about the magnitude of autumn juvenile mortality and its consequences for the population dynamics of Teal. Lack of correlations between annual proportions of juveniles in the hunting bag and an index of Teal breeding success in Finland may result from such high and variable inter-annual mortality.

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“…Mazerolle and Hobson 2007;Morton 1984, Payevsky 1995Rogers et al 1989), waterfowl (e.g. Guillemain et al 2009) and waders (e.g. Fernandez and Lank 2007;O'Hara et al 2006).…”

mentioning

confidence: 99%

Differential migration by age and sex in central European Ospreys Pandion haliaetus

Bai

Schmidt²

2011

J Ornithol

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Differential migration reflects various constraints and selective forces on different individuals in a population, and has been explained by several hypotheses. Most previous studies about differential migration focused on only one aspect (e.g. spring timing, autumn timing or wintering area), which could not give a full picture of differential migration of the study population and carry out an overall investigation into the hypotheses. In this study, we analyse the migration patterns of European Ospreys Pandion haliaetus ringed in Germany based on the ring recovery database between 1980 and 2008. The migration routes of the study population form a broad front between south and southwest of the ringing area, and the wintering sites are in West Africa south of the Sahara and around the western Mediterranean. We demonstrate differential migration of the population in both spring and autumn timings as well as in the use of wintering grounds. Adult (third year and older) males return earliest to the breeding area in spring, followed by adult females and then twoyear-old birds. In autumn, the adult females leave the breeding area earlier than adult males, while the migration of first-year Ospreys takes place over a wide time-span. Adult males were discovered mainly around the western Mediterranean in winter, closer to the ringing area than adult females and younger birds. We suggest that the selection for prior access to breeding resources on males shapes the patterns of differential migration in Ospreys.

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Differential migration of the sexes cannot be explained by the body size hypothesis in Teal

Cited by 17 publications

References 26 publications

Individual quality persists between years: individuals retain body condition from one winter to the next in Teal

Individual quality persists between years: individuals retain body condition from one winter to the next in Teal

How many juvenile Teal Anas crecca reach the wintering grounds? Flyway-scale survival rate inferred from wing age-ratios

Differential migration by age and sex in central European Ospreys Pandion haliaetus

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