Age‐specific breeding probability in black brant: effects of population density

Sedinger, James S.; Lindberg, Mark S.; Chelgren, Nathan D.

doi:10.1046/j.0021-8790.2001.00535.x

Cited by 53 publications

(75 citation statements)

References 53 publications

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“…Density-dependent processes often interact with other variables including predation, harvest, and genetics, as well as density independent factors such as climate-those interactions can make density-related processes difficult to document (McCullough 1979(McCullough , 1990White and Bartmann 1997;Bowyer et al 1999;Aanes et al 2000). Density dependence has been investigated in birds (Sedinger et al 2001;Both and Visser 2003;Elmberg et al 2003), small mammals (Aars and Ims 2002), carnivorous mammals (Fryxell et al 1999;Macdonald et al 2002), and large, herbivorous mammals (McCullough 1979;Kie and White 1985;Bowyer et al 1999;Mysterud et al 2000;Saether et al 2002;Toigo et al 2002) with varying results, because most organisms exhibit both density-dependent and density-independent characteristics.…”

Section: Introductionmentioning

confidence: 98%

Density-dependent effects on physical condition and reproduction in North American elk: an experimental test

et al. 2004

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Density dependence plays a key role in life-history characteristics and population ecology of large, herbivorous mammals. We designed a manipulative experiment to test hypotheses relating effects of density-dependent mechanisms on physical condition and fecundity of North American elk (Cervus elaphus) by creating populations at low and high density. We hypothesized that if density-dependent effects were manifested principally through intraspecific competition, body condition and fecundity of females would be lower in an area of high population density than in a low-density area. Thus, we collected data on physical condition and rates of pregnancy in each experimental population. Our manipulative experiment indicated that density-dependent feedbacks affected physical condition and reproduction of adult female elk. Age-specific pregnancy rates were lower in the high-density area, although there were no differences in pregnancy of yearlings or in age at peak reproduction between areas. Age-specific rates of pregnancy began to diverge at 2 years of age between the two populations and peaked at 6 years old. Pregnancy rates were most affected by body condition and mass, although successful reproduction the previous year also reduced pregnancy rates during the current year. Our results indicated that while holding effects of winter constant, density-dependent mechanisms had a much greater effect on physical condition and fecundity than density-independent factors (e.g., precipitation and temperature). Moreover, our results demonstrated effects of differing nutrition resulting from population density during summer on body condition and reproduction. Thus, summer is a critical period for accumulation of body stores to buffer animals against winter; more emphasis should be placed on the role of spring and summer nutrition on population regulation in large, northern herbivores.

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Section: Introductionmentioning

confidence: 98%

Density-dependent effects on physical condition and reproduction in North American elk: an experimental test

et al. 2004

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“…In addition to generating estimates of apparent U, the robust design provides estimates of temporary emigration (c), capture probability ( p), and recapture probability (c). Our goal was to generate reliable estimates of U, given potential variance associated with temporary emigration (Kendall et al 1997), which may have occurred if males did not breed in each year of the study (Sedinger et al 2001). In a previous analysis we found that male density during year t was the best predictor of c tþ1 , so we incorporated a structure of c using this density covariate for all models.…”

Section: Survival Analysismentioning

confidence: 99%

Characteristics of climate and landscape disturbance influence the dynamics of greater sage‐grouse populations

et al. 2012

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Life histories determine how organisms interact with their environment and predict how populations respond to environmental change. Understanding relationships between life histories and environmental variability is therefore crucial for effective conservation under changing environmental conditions. Greater sage‐grouse (Centrocercus urophasianus) is a species of major conservation concern in western North America following widespread disturbance of the sagebrush ecosystems to which they are endemic. Using robust design and Pradel capture‐mark‐recapture models, we evaluated the influence of climatic processes and disturbance associated with post‐wildfire exotic grass invasion on annual survival, per‐capita recruitment, and population growth of breeding male sage‐grouse in eastern Nevada, USA. Climatic processes, indexed by annual rainfall and maximum summertime temperatures, had a strong relationship with recruitment and adult survival, respectively. The range of variation in recruitment during the study was greater than the range of variation in survival, consistent with a life‐history strategy that features lengthened lifespan to capitalize on periodically favorable reproductive conditions. Annual variation in precipitation variables (e.g., rainfall or snow depth) explained as much as 75% of the annual variance in population size during the study. Our results are consistent with bottom‐up regulation of sage‐grouse populations, where abundance is determined in large part by climate‐driven variation in resource availability. Exotic grasslands had a negative influence on recruitment that was interactive with annual rainfall; recruitment was consistently low in areas with a substantial exotic grassland footprint even following years of favorable rainfall. We found males breeding at leks with substantial exotic grassland impacts had lower annual survival compared to males at leks surrounded by native sagebrush habitats. However, models containing an interaction between exotic grasslands and maximum summer temperature were not clearly superior to models that considered only additive effects of the two variables. This research has significant implications for sage‐grouse persistence in a changing climate, where more frequent drought and increased spread of exotic grasslands will have negative impacts on sage‐grouse populations.

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“…Such a threshold has been well documented in both mammal and reptile species (reviewed by Shine 2003, Bonenfant et al 2009). Despite breeding propensity being considered a key demographic parameter (Sedinger et al 2001), it is the least understood reproductive decision in avian species (Sedinger et al 2001, Reed et al 2004. This parameter has rarely been tested in birds because non-breeders are often entirely absent from the breeding grounds, making comparisons to breeding birds challenging (Chastel 1995), and individuals are difficult to both capture…”

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confidence: 99%

Unpredictable perturbation reduces breeding propensity regardless of pre‐laying reproductive readiness in a partial capital breeder

Legagneux

Hennin

Gilchrist

et al. 2016

Journal of Avian Biology

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Theoretically, individuals of migratory species should optimize reproductive investment based on a combination of timing of and body condition at arrival on the breeding grounds. A minimum threshold body mass is required to initiate reproduction, and the timing of reaching this threshold is critical because of the trade-off between delaying breeding to gain in condition against the declining value of offspring with later reproductive timing. Long-lived species have the flexibility within their life history to skip reproduction in a given year if they are unable to achieve this theoretical mass threshold. Although the decision to breed or not is an important parameter influencing population dynamics, the mechanisms underlying this decision are poorly understood. Here, we mimicked an unpredictable environmental perturbation that induced a reduction in body mass of Arctic pre-breeding (before the laying period) female common eiders Somateria mollissima; a long-lived migratory seaduck, while controlling for individual variation in the pre-laying physiological reproductive readiness via vitellogenin (VTG) -a yolk-targeted lipoprotein. Our aim was to causally determine the interaction between body condition and pre-laying reproductive readiness (VTG) on breeding propensity by experimentally reducing body mass in treatment females. We first demonstrated that arrival body condition was a key driver of breeding propensity. Secondly, we found that treatment and VTG levels interacted to influence breeding propensity, indicating that our experimental manipulation, mimicking an unpredictable food shortage, reduced breeding propensity, regardless of the degree of pre-laying physiological reproductive readiness (i.e. timing of ovarian follicles recruitment). Our experiment demonstrates that momentary environmental perturbations during the prebreeding period can strongly affect the decision to breed, a key parameter driving population dynamics.

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Age‐specific breeding probability in black brant: effects of population density

Cited by 53 publications

References 53 publications

Density-dependent effects on physical condition and reproduction in North American elk: an experimental test

Density-dependent effects on physical condition and reproduction in North American elk: an experimental test

Characteristics of climate and landscape disturbance influence the dynamics of greater sage‐grouse populations

Unpredictable perturbation reduces breeding propensity regardless of pre‐laying reproductive readiness in a partial capital breeder

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