Vital rates of intermittent nonbreeders and returning breeders strongly influence population dynamics of Somateria mollissima (Common Eider)
Vital rates of intermittent nonbreeders and returning breeders strongly influence population dynamics of Somateria mollissima (Common Eider)
Risks and costs associated with reproduction may induce iteroparous species to employ intermittent breeding, whereby individuals forgo attempting reproduction in some breeding periods following recruitment to the breeding population. We explore this behavior through population-level analyses of Somateria mollissima (Common Eider), quantifying the survival cost of breeding and hence one benefit of skipping. Nonbreeding in a given year may be a short-term response to expected low fitness returns, avoiding either breeding-induced mortality or low offspring value. Alternatively, or additionally, intermittent breeding may be a long-term strategy maximizing lifetime fitness, with breeding trajectories that include nonbreeding years resulting in more recruited offspring over the whole life course than those with the same number of consecutive breeding attempts. Reanalysis of 3 studies reporting annual mortality schedules for S. mollissima allowed estimation of the proportion of mortality incurred during the peak breeding season (~50%) and hence the difference in survival rates between breeders and nonbreeders. These were incorporated into a life cycle and associated matrix population model with a “refreshed breeder” stage to which individuals transition for the time step following nonbreeding. We show that the transition to this stage strongly influences population growth rate—being more than twice as important as reproduction by continued breeders—mostly driven by the possibility of differential survival after skipping breeding. Our results emphasize the benefits of long-term individual-based studies that can identify refreshed breeders to further our understanding of intermittent breeding. Specifically, the accuracy of population projections could be improved by factoring in transitions following skipped breeding, and management enhanced by interventions facilitating return to the breeding pool, such as nest shelter provision.
Common Eider, modèle matriciel de population, Somateria mollissima, seaduck, breeding propensity, dynamique de population, mortalité, propension à la reproduction, reproducteur rafraîchi, population dynamics, matrix population model, vital rates, canard de mer, refreshed breeder, mortality, taux vitaux
Nicol-Harper, Alex
b4d622c9-7cf5-4fd7-9221-128f29ade156
Wood, Kevin A.
9b23af3a-4b22-459a-9fb8-a80ea690be01
Hilton, Geoff M.
77c4be6c-31ea-49c6-8e20-55f21e16384c
Doncaster, C. Patrick
0eff2f42-fa0a-4e35-b6ac-475ad3482047
Ezard, Thomas H.G.
a143a893-07d0-4673-a2dd-cea2cd7e1374
12 February 2025
Nicol-Harper, Alex
b4d622c9-7cf5-4fd7-9221-128f29ade156
Wood, Kevin A.
9b23af3a-4b22-459a-9fb8-a80ea690be01
Hilton, Geoff M.
77c4be6c-31ea-49c6-8e20-55f21e16384c
Doncaster, C. Patrick
0eff2f42-fa0a-4e35-b6ac-475ad3482047
Ezard, Thomas H.G.
a143a893-07d0-4673-a2dd-cea2cd7e1374
Nicol-Harper, Alex, Wood, Kevin A., Hilton, Geoff M., Doncaster, C. Patrick and Ezard, Thomas H.G.
(2025)
Vital rates of intermittent nonbreeders and returning breeders strongly influence population dynamics of Somateria mollissima (Common Eider).
Ornithology, 142 (2), [ukae057].
(doi:10.1093/ornithology/ukae057).
Abstract
Risks and costs associated with reproduction may induce iteroparous species to employ intermittent breeding, whereby individuals forgo attempting reproduction in some breeding periods following recruitment to the breeding population. We explore this behavior through population-level analyses of Somateria mollissima (Common Eider), quantifying the survival cost of breeding and hence one benefit of skipping. Nonbreeding in a given year may be a short-term response to expected low fitness returns, avoiding either breeding-induced mortality or low offspring value. Alternatively, or additionally, intermittent breeding may be a long-term strategy maximizing lifetime fitness, with breeding trajectories that include nonbreeding years resulting in more recruited offspring over the whole life course than those with the same number of consecutive breeding attempts. Reanalysis of 3 studies reporting annual mortality schedules for S. mollissima allowed estimation of the proportion of mortality incurred during the peak breeding season (~50%) and hence the difference in survival rates between breeders and nonbreeders. These were incorporated into a life cycle and associated matrix population model with a “refreshed breeder” stage to which individuals transition for the time step following nonbreeding. We show that the transition to this stage strongly influences population growth rate—being more than twice as important as reproduction by continued breeders—mostly driven by the possibility of differential survival after skipping breeding. Our results emphasize the benefits of long-term individual-based studies that can identify refreshed breeders to further our understanding of intermittent breeding. Specifically, the accuracy of population projections could be improved by factoring in transitions following skipped breeding, and management enhanced by interventions facilitating return to the breeding pool, such as nest shelter provision.
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Accepted/In Press date: 29 October 2024
e-pub ahead of print date: 30 January 2025
Published date: 12 February 2025
Keywords:
Common Eider, modèle matriciel de population, Somateria mollissima, seaduck, breeding propensity, dynamique de population, mortalité, propension à la reproduction, reproducteur rafraîchi, population dynamics, matrix population model, vital rates, canard de mer, refreshed breeder, mortality, taux vitaux
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Local EPrints ID: 498289
URI: http://eprints.soton.ac.uk/id/eprint/498289
ISSN: 0004-8038
PURE UUID: 88514bcf-24d2-415d-9543-99a41d400d4a
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Date deposited: 13 Feb 2025 18:03
Last modified: 04 Sep 2025 02:14
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Author:
Kevin A. Wood
Author:
Geoff M. Hilton
Author:
Thomas H.G. Ezard
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