Autumn survival inferred from wing age ratios: Wigeon juvenile survival half that of adults at best?

Guillemain, Matthieu; Fox, Anthony D.; Pöysä, Hannu; Väänänen, Veli‐Matti; Christensen, Thomas Kjær; Triplet, Patrick; Schricke, Vincent; Korner‐Nievergelt, Fränzi

doi:10.1007/s10336-012-0899-y

Cited by 18 publications

(20 citation statements)

References 18 publications

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“…However, our results suggest that this vulnerability declines during the winter, contradicting the assumption of Guillemain et al . () that there was no basis to expect that in the course of the season juvenile Wigeon ‘gradually learn to avoid hunters’, which according to our data could be the case. These results confirm the importance of accounting for temporal components of demographic measures and the need for calibration, in this case not just to account for bias in hunted samples for age ratios but to also incorporate temporal variation in this bias.…”

Section: Discussioncontrasting

confidence: 54%

Age‐ratio bias among hunter‐based surveys of Eurasian Wigeon Anas penelope based on wing vs. field samples

Fox

Clausen

Dalby

et al. 2014

Ibis

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We compared age and sex ratios among Eurasian Wigeon Anas penelope derived from Danish field observations and hunter‐based shot samples throughout an entire winter. Sex ratios did not differ significantly between the two samples. Overall, first‐year males were more than three times more likely to be represented than adult males in the hunter sample compared with field samples and were 7–20 times overrepresented in the hunting sample at the beginning of the season. These results confirm the need to account for such bias and its temporal variation when using the results of hunting surveys to model population parameters. Hunter‐shot age ratios may provide a long‐term measure of reproductive success of dabbling duck flyway populations given an understanding of such bias.

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Section: Discussioncontrasting

confidence: 54%

Age‐ratio bias among hunter‐based surveys of Eurasian Wigeon Anas penelope based on wing vs. field samples

Fox

Clausen

Dalby

et al. 2014

Ibis

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“…; Guillemain et al . ). The migration period is considered a critical phase of annual survival (Newton ) with increased mortality during migration compared to stationary periods (Owen & Black ; Sillett & Holmes ; Strandberg et al .…”

Section: Introductionmentioning

confidence: 97%

“…dynamics. In many migrating bird species, juveniles in their first year exhibit considerably lower annual survival rates compared to adults (Schaub & Pradel 2004;Menu, Gauthier & Reed 2005;Strandberg et al 2010;Sergio et al 2011;Guillemain et al 2013). The migration period is considered a critical phase of annual survival (Newton 2006) with increased mortality during migration compared to stationary periods (Owen & Black 1989;Sillett & Holmes 2002;Strandberg et al 2010;Klaassen et al 2014;Lok, Overdijk & Piersma 2015) and juveniles in particular suffer higher mortality during the strenuous journeys (Owen & Black 1989;Menu, Gauthier & Reed 2005;Strandberg et al 2010;Sergio et al 2014).…”

mentioning

confidence: 99%

The challenges of the first migration: movement and behaviour of juvenile vs. adult white storks with insights regarding juvenile mortality

Rotics

Kaatz²,

Resheff

et al. 2016

Journal of Animal Ecology

166

209

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Summary 1.Migration conveys an immense challenge, especially for juvenile birds coping with enduring and risky journeys shortly after fledging. Accordingly, juveniles exhibit considerably lower survival rates compared to adults, particularly during migration. Juvenile white storks (Ciconia ciconia), which are known to rely on adults during their first fall migration presumably for navigational purposes, also display much lower annual survival than adults. 2. Using detailed GPS and body acceleration data, we examined the patterns and potential causes of age-related differences in fall migration properties of white storks by comparing first-year juveniles and adults. We compared juvenile and adult parameters of movement, behaviour and energy expenditure (estimated from overall dynamic body acceleration) and placed this in the context of the juveniles' lower survival rate. 3. Juveniles used flapping flight vs. soaring flight 23% more than adults and were estimated to expend 14% more energy during flight. Juveniles did not compensate for their higher flight costs by increased refuelling or resting during migration. When juveniles and adults migrated together in the same flock, the juvenile flew mostly behind the adult and was left behind when they separated. Juveniles showed greater improvement in flight efficiency throughout migration compared to adults which appears crucial because juveniles exhibiting higher flight costs suffered increased mortality. 4. Our findings demonstrate the conflict between the juveniles' inferior flight skills and their urge to keep up with mixed adult-juvenile flocks. We suggest that increased flight costs are an important proximate cause of juvenile mortality in white storks and likely in other soaring migrants and that natural selection is operating on juvenile variation in flight efficiency.

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“…Higher juvenile recovery probabilities have been found for many waterfowl species (Reynolds ; Guillemain et al. , ) including black duck (Reed and Boyd ; Parker ; Longcore et al. ).…”

Section: Discussionmentioning

confidence: 94%

“…There was a strong tendency for higher juvenile recovery with all other band types, but the differences were not significant according to the 95% credible intervals. Higher juvenile recovery probabilities have been found for many waterfowl species (Reynolds 1987;Guillemain et al 2010Guillemain et al , 2013 including black duck (Reed and Boyd 1974;Parker 1991;Longcore et al 2000a). The increased vulnerability of juveniles is typically attributed to naivety of individuals not previously exposed to hunting (Francis et al 1992;Calvert et al 2005).…”

Section: Recovery Probabilitymentioning

confidence: 94%

Spatial and temporal variation in harvest probabilities for American black duck

Roy

Cumming

McIntire

2015

Ecology and Evolution

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Assessing spatial variation in waterfowl harvest probabilities from banding data is challenging because reporting and recovery probabilities have distinct spatial patterns that covary temporally with harvesting regulations, hunter effort, and reporting methods. We analyzed direct band recovery data from American black ducks banded on the Canadian breeding grounds from 1970 through 2010. Data were registered to a 1-degree grid and analyzed using hierarchical logistic regression models with spatially correlated errors to estimate the annual probabilities of band recovery and the proportion of individuals recovered in Canada. Probability of harvest was estimated from these values, in combination with independent estimates of reporting probabilities in Canada and the USA. Model covariates included estimates of hunting effort and factors for harvest regulation and band reporting methods. Both the band recovery processes and the proportion of individuals recovered in Canada had significant spatial structure. Recovery probabilities were highest in southern Ontario, along the Saint Lawrence River in Quebec, and in Nova Scotia. Black ducks breeding in Nova Scotia and southern Quebec were harvested predominantly in Canada. Recovery probabilities for juveniles were correlated with hunter effort, while the adult recoveries were weakly correlated with the implementation of stricter harvest regulations in the early 1980s. Mean harvest probability decreased in the northern portion of the survey area but remained stable or even increased in the south. Harvest probabilities for juveniles in 2010 exceeded 20% in southern Quebec and the Atlantic provinces. Our results demonstrate fine-scale variation in harvest probabilities for black duck on the Canadian breeding ground. In particular, harvest probabilities should be closely monitored along the Saint Lawrence River system and in the Atlantic provinces to avoid overexploitation.

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Autumn survival inferred from wing age ratios: Wigeon juvenile survival half that of adults at best?

Cited by 18 publications

References 18 publications

Age‐ratio bias among hunter‐based surveys of Eurasian Wigeon Anas penelope based on wing vs. field samples

Age‐ratio bias among hunter‐based surveys of Eurasian Wigeon Anas penelope based on wing vs. field samples

The challenges of the first migration: movement and behaviour of juvenile vs. adult white storks with insights regarding juvenile mortality

Spatial and temporal variation in harvest probabilities for American black duck

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