Sensitivity Analyses of the Life Cycle of Midcontinent Mallards

Hoekman, Steven T.; Mills, L. Scott; Howerter, David W.; Devries, James H.; Ball, I. J.

doi:10.2307/3803153

Cited by 196 publications

(235 citation statements)

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“…Given annual survival estimates of ≈0.58 for adult female Mallards based on band-recovery data (Hoekman et al 2002), this suggests that approximately 80% of all mortality occurs during just one third of the year during the breeding season, with virtually all of the 0.08 additional mortality outside the breeding season presumably due to hunting mortality. Studies of radio-marked female Mallards on their wintering ranges confirm that survival is higher during the nonbreeding season than during the breeding season, and that virtually all mortality during nonbreeding is caused by hunting (Dugger et al 1994, Fleskes et al 2007, Dooley et al 2010; but see Bergan and Smith 1993).…”

Section: Discussionmentioning

confidence: 99%

“…4), a pattern we cannot readily explain. Nevertheless, given that the highest mortality of female Mallards was associated with nesting activity, providing safer nesting habitats would seem to provide twin benefits of enhanced nest survival as well as greater survival of adult females during the breeding season (Reynolds et al 1995, Hoekman et al 2002.…”

Section: Discussionmentioning

confidence: 99%

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Costs of Reproduction in Breeding Female Mallards: Predation Risk during Incubation Drives Annual Mortality

Arnold¹,

Roche²,

Devries³

et al. 2012

ACE

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ABSTRACT. The effort expended on reproduction may entail future costs, such as reduced survival or fecundity, and these costs can have an important influence on life-history optimization. For birds with precocial offspring, hypothesized costs of reproduction have typically emphasized nutritional and energetic investments in egg formation and incubation. We measured seasonal survival of 3856 radio-marked female Mallards (Anas platyrhynchos) from arrival on the breeding grounds through brood-rearing or cessation of breeding. There was a 2.5-fold direct increase in mortality risk associated with incubating nests in terrestrial habitats, whereas during brood-rearing when breeding females occupy aquatic habitats, mortality risk reached seasonal lows. Mortality risk also varied with calendar date and was highest during periods when large numbers of Mallards were nesting, suggesting that prey-switching behaviors by common predators may exacerbate risks to adults in all breeding stages. Although prior investments in egg laying and incubation affected mortality risk, most relationships were not consistent with the cost of reproduction hypothesis; birds with extensive prior investments in egg production or incubation typically survived better, suggesting that variation in individual quality drove both relationships. We conclude that for breeding female Mallards, the primary cost of reproduction is a fixed cost associated with placing oneself at risk to predators while incubating nests in terrestrial habitats.RÉSUMÉ. L'effort investi à la reproduction peut avoir une incidence sur les coûts futurs -comme un faible taux de survie ou de fertilité -et ces coûts peuvent grandement influencer l'optimisation du cycle biologique. Chez les oiseaux dont les jeunes sont nidifuges, les coûts hypothétiques de la reproduction sont surtout liés aux efforts nutritionnel et énergétique investis dans la formation des oeufs et à l'incubation. Dans le cadre de cette étude, nous avons mesuré le taux de survie saisonnier de 3 856 Canards colverts (Anas platyrhynchos) femelles munies d'un émetteur radio, de leur arrivée sur les aires de nidification jusqu'à ce que l'élevage des jeunes soit complété ou jusqu'à l'échec de la nidification. Le taux de mortalité était de 2,5 fois plus élevé chez les femelles qui couvaient leurs oeufs en milieu terrestre, tandis qu'il a était à son plus bas niveau saisonnier au moment de l'élevage des jeunes en milieu aquatique. Le taux de mortalité a aussi varié en fonction de la date : il était à son maximum au moment où de nombreux Canards colverts nichaient, ce qui laisse croire que le changement de proies dans la diète des prédateurs communs pourrait exacerber le risque de mortalité chez les femelles à toutes les étapes de la nidification. Même si les efforts investis dans la ponte et l'incubation ont eu un effet sur le taux de mortalité, la plupart des relations n'étaient pas conformes aux prédictions de l'hypothèse des coûts de la reproduction; les femelles qui ont grandement investi dans la production d'oeufs ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Costs of Reproduction in Breeding Female Mallards: Predation Risk during Incubation Drives Annual Mortality

Arnold¹,

Roche²,

Devries³

et al. 2012

ACE

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“…Breeding-season survival has been ranked very highly as an influence on population growth rates, not only for lesser scaup (Allen et al, 1999;Koons, 2001), but also for prairie-breeding mallard (Anas platyrhynchos) females (Hoekman et al, 2002) and northern pintail (Anas acuta) breeding in boreal forest habitat in Alaska (Flint et al, 1998). Estimates of breeding-season survival are needed to further assess these hypotheses about scaup population decline (Allen et al, 1999;Afton and Anderson, 2001) and to develop population models that may be important to help understand the causes of decline (Horvitz et al, 1997;Caswell, 2000).…”

Section: Introductionmentioning

confidence: 99%

Breeding Season Survival of Female Lesser Scaup in the Northern Boreal Forest

Brook¹,

Clark²

2010

ARCTIC

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ABSTRACT. One hypothesis advanced to explain the decline in lesser scaup (Aythya affinis) populations during the past 20 years is that adult female survival has decreased. However, no survival probability estimates exist for the boreal forest, the region where most scaup breed. We captured and radio-marked female lesser scaup (n = 42) near Yellowknife, Northwest Territories, Canada, just before the breeding season in 1999 and 2000. Constant weekly survival probability was estimated using a Cormack-JollySeber model (0.96). We extrapolate this rate to estimate survival probability for the nesting season (0.80, SE = 0.09), the period when females are at greatest risk of predation. Recent estimates of annual mortality (42%) suggest that about 50% of annual female mortality occurs during the breeding season, a result similar to recent conclusions from studies of prairie-nesting lesser scaup. Further, our survival estimate provides information required to produce preliminary models of population dynamics for boreal lesser scaup, a step that could greatly improve our understanding of decline in this species.Key words: Aythya affinis, lesser scaup, boreal forest, breeding season survival, recapture probability, survival probability RÉSUMÉ. Une hypothèse qui a été avancée pour expliquer le déclin des populations du petit fuligule (Aythya affinis) au cours des 20 dernières années est que la survie de la femelle adulte a baissé. Il n'existe cependant aucune estimation de la probabilité de survie pour la forêt boréale, région où se reproduisent la plupart des fuligules. Juste avant la saison de reproduction en 1999 et 2000, on a capturé, près de Yellowknife dans les Territoires du Nord-Ouest, des fuligules femelles (n = 42) qu'on a équipées de radio-émetteurs. À l'aide du modèle de Cormack-Jolly-Seber, on a estimé la probabilité de survie hebdomadaire (0,96) sur une base constante. On a extrapolé ce taux pour estimer la probabilité de survie pour la saison de reproduction (0,80, erreur-type = 0,09), période qui représente pour les femelles le plus grand risque de prédation. De récentes estimations de la mortalité annuelle (42 %) suggèrent qu'environ 50 % de cette dernière chez la population femelle se produit durant la saison de reproduction, ce qu'on retrouve aussi dans les résultats d'études récentes sur le fuligule nichant dans la prairie. De plus, notre estimation de la survie offre des renseignements qui sont nécessaires à l'élaboration de modèles préliminaires de la dynamique des populations chez le fuligule boréal, une étape qui permettrait d'améliorer considérablement notre compréhension du déclin de l'espèce.Mots clés: Aythya affinis, fuligule, forêt boréale, survie durant la saison de reproduction, probabilité de recapture, probabilité de survie Traduit pour la revue Arctic par Nésida Loyer.

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“…However, it is thought that like other ground-nesting birds (Johnson et al 1992, Hoekman et al 2002, Hagen et al 2009), nest survival plays an influential role in population dynamics (Taylor et al 2012). As such, conservation recommendations have often been focused on improving nesting habitat conditions (Johnson and Braun 1999, Connelly et al 2000, Taylor et al 2012, Kirol et al 2015.…”

Section: Introductionmentioning

confidence: 99%

Evaluating vital rate contributions to greater sage‐grouse population dynamics to inform conservation

et al. 2016

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Abstract. Species conservation efforts often use short-term studies that fail to identify the vital rates that contribute most to population growth. Although the greater sage-grouse (Centrocercus urophasianus; sage-grouse) is a candidate for protection under the U.S. Endangered Species Act, and is sometimes referred to as an umbrella species in the sagebrush (Artemisia spp.) biome of western North America, the failure of proposed management strategies to focus on key vital rates that may contribute most to achieving population stability remains problematic for sustainable conservation. To address this dilemma, we performed both prospective and retrospective perturbation analyses of a life cycle model based on a 12-yr study that encompassed nearly all sage-grouse vital rates. To validate our population models, we compared estimates of annual finite population growth rates (λ) from our female-based life cycle models to those attained from male-based lek counts. Post-fledging (i.e., after second year, second year, and juvenile) female survival parameters contributed most to past variation in λ during our study and had the greatest potential to change λ in the future, indicating these vital rates as important determinants of sage-grouse population dynamics. In addition, annual estimates of λ from female-based life cycle models and malebased lek data were similar, providing the most rigorous evidence to date that lek counts of males can serve as a valid index of sage-grouse population change. Our comparison of fixed and mixed statistical models for evaluating temporal variation in nest survival and initiation suggest that conservation planners use caution when evaluating short-term nesting studies and using associated fixed-effect results to develop conservation objectives. In addition, our findings indicated that greater attention should be paid to those factors affecting sage-grouse post-fledging females. Our approach demonstrates the need for more long-term studies of species vital rates across the life cycle. Such studies should address the decoupling of sampling variation from underlying process (co)variation in vital rates, identification of how such variation drives population dynamics, and how decision makers can use this information to re-direct conservation efforts to address the most limiting points in the life cycle for a given population.

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Sensitivity Analyses of the Life Cycle of Midcontinent Mallards

Cited by 196 publications

References 77 publications

Costs of Reproduction in Breeding Female Mallards: Predation Risk during Incubation Drives Annual Mortality

Costs of Reproduction in Breeding Female Mallards: Predation Risk during Incubation Drives Annual Mortality

Breeding Season Survival of Female Lesser Scaup in the Northern Boreal Forest

Evaluating vital rate contributions to greater sage‐grouse population dynamics to inform conservation

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