Individual improvements and selective mortality shape lifelong migratory performance

Sergio, Fabrizio; Tanferna, Alessandro; Stephanis, Renaud de; López‐Jiménez, Lidia; Blas, Julio; Tavecchia, Giacomo; Preatoni, Damiano; Hiraldo, Fernando

doi:10.1038/nature13696

Cited by 276 publications

(336 citation statements)

References 37 publications

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“…Studies however varied in their estimates, from a low but significant value of 0.09 in a very large sample of Cliff Swallows Petrochelidon pyrrhonota (Brown & Brown 1998), to a high value of 0.67 in a small sample of Black Kites Milvus migrans tagged with a satellitetransmitter (Sergio et al 2014). Various recent studies have used small samples of mostly large-bodied tagged birds.…”

Section: Discussionmentioning

confidence: 99%

“…Starting with the latter, some studies have analysed males and females simultaneously (e.g. Gill et al 2014, Sergio et al 2014, and if sexes arrive on average at different times (as is often the case: current study, Lourenço et al 2011, Gordo et al 2013, Coppack et al 2006, the repeatability may be an effect of sex, rather than of individual variation within sexes. Some studies have standardized arrival dates to the annual mean, whereas other have not.…”

Section: Discussionmentioning

confidence: 99%

“…This also suggests that young birds still need to learn how to migrate, and therefore show larger variability in arrival dates (Sergio et al 2014).…”

Section: Age Effectmentioning

confidence: 99%

“…Hence, our estimate of first-year arrival may be biased towards the successful individuals. The reason why young birds may travel slower and arrive later could be inexperience (Sergio et al 2014), but also that their probability to breed is low, and therefore they take less risks during migration (Hill 1989).…”

Section: Age Effectmentioning

confidence: 99%

“…Note that many locally born individuals are not observed in their first year (Harvey et al 1985, Sternberg 1989, Potti & Montalvo 1991b. While analysing the age effect we also have to consider whether previous experience affects arrival date (Sternberg 1989, Sternberg et al 2002, Sergio et al 2014.…”

Section: Data Selectionmentioning

confidence: 99%

See 4 more Smart Citations

Repeatability in Spring Arrival Dates in Pied Flycatchers Varies Among Years and Sexes

Both¹,

Bijlsma²,

Ouwehand³

2016

Ardea

117

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…This also suggests that young birds still need to learn how to migrate, and therefore show larger variability in arrival dates (Sergio et al 2014).…”

Section: Age Effectmentioning

confidence: 99%

Section: Age Effectmentioning

confidence: 99%

Section: Data Selectionmentioning

confidence: 99%

See 3 more Smart Citations

Repeatability in Spring Arrival Dates in Pied Flycatchers Varies Among Years and Sexes

Both¹,

Bijlsma²,

Ouwehand³

2016

Ardea

117

View full text Add to dashboard Cite

Demographic modeling to fine‐tune conservation targets: importance of pre‐adults for the decline of an endangered raptor

Tavecchia

Blas²,

Tanferna³

et al. 2021

Ecological Applications

Self Cite

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Large, long-lived species with slow life histories and protracted pre-breeding stages are particularly susceptible to declines and extinction, often for unknown causes. Here, we show how demographic modeling of a medium-sized raptor, the Red Kite Milvus milvus, can aid to refocus conservation research and attention on the most likely mechanisms driving its decline. Red Kites' survival and reproduction increased through three sequential stages for 1-2, 3-6, and 7-30 yr of age, mainly corresponding to individuals that are dispersing, attempting to gain a territory, and breeding. As typical of long-lived species, elasticities were highest for adult (≥7 yr old) survival, but this was high, with little scope for improvement. Instead, the declines were driven by an extremely low survival of pre-adults in their first years of life, which weakened the whole demographic system by nullifying the offspring contribution of adults and curtailing their replacement by recruits. For example, 27 pairs were necessary to generate a single prime age adult. Simulation of management scenarios suggested that the decline could be halted most parsimoniously by increasing pre-adult survival to the mean levels recorded for other areas, while only the synergistic, simultaneous improvement of breeding success, adult and pre-adult survival could generate a recovery. We propose three actions to attain such goals through selective supplementary feeding of both breeding and non-breeding individuals, and through mortality improvement by GPS remote-sensing devices employed as surveillance monitoring tools. Our results show how improving demographic models by using real, local vital rates rather than "best guess" vital rates can dramatically improve model realism by refocusing attention on the actual stages and mortality causes in need of manipulation, thus building precious time and resources for conservation management. These results also highlight the frequent key role of pre-adult survival for the management of long-lived species, coherent with the idea of demographic systems as integrated chains only as strong as their weakest link.

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Insularity determines nestling sex ratio variation in Egyptian vulture populations

Gómez‐López

Sanz‐Aguilar

Carrete

et al. 2023

Ecology and Evolution

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Variation in offspring sex ratio, particularly in birds, has been frequently studied over the last century, although seldom using long‐term monitoring data. In raptors, the cost of raising males and females is not equal, and several variables have been found to have significant effects on sex ratio, including food availability, parental age, and hatching order. Sex ratio differences between island populations and their mainland counterparts have been poorly documented, despite broad scientific literature on the island syndrome reporting substantial differences in population demography and ecology. Here, we assessed individual and environmental factors potentially affecting the secondary sex ratio of the long‐lived Egyptian vulture Neophron percnopterus. We used data collected from Spanish mainland and island populations over a ca. 30‐year period (1995–2021) to assess the effects of insularity, parental age, breeding phenology, brood size, hatching order, type of breeding unit (pairs vs. trios), and spatial and temporal variability on offspring sex ratio. No sex bias was found at the population level, but two opposite trends were observed between mainland and island populations consistent with the island syndrome. Offspring sex ratio was nonsignificantly female‐biased in mainland Spain (0.47, n = 1112) but significantly male‐biased in the Canary Islands (0.55, n = 499), where a male‐biased mortality among immatures could be compensating for offspring biases and maintaining a paired adult sex ratio. Temporal and spatial variation in food availability might also have some influence on sex ratio, although the difficulties in quantifying them preclude us from determining the magnitude of such influence. This study shows that insularity influences the offspring sex ratio of the Egyptian vulture through several processes that can affect island and mainland populations differentially. Our research contributes to improving our understanding of sex allocation theory by investigating whether sex ratio deviations from parity are possible as a response to changing environments comprised by multiple and complexly interrelated factors.

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Individual improvements and selective mortality shape lifelong migratory performance

Cited by 276 publications

References 37 publications

Repeatability in Spring Arrival Dates in Pied Flycatchers Varies Among Years and Sexes

Repeatability in Spring Arrival Dates in Pied Flycatchers Varies Among Years and Sexes

Demographic modeling to fine‐tune conservation targets: importance of pre‐adults for the decline of an endangered raptor

Insularity determines nestling sex ratio variation in Egyptian vulture populations

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