Density dependence maintains long‐term stability despite increased isolation and inbreeding in the Florida Scrub‐Jay

Ecology Letters, Год журнала: 2024, Номер 27(12)

Опубликована: Дек. 1, 2024

Isolation caused by anthropogenic habitat fragmentation can destabilize populations. Populations relying on the inflow of immigrants face reduced fitness due to inbreeding depression as fewer new individuals arrive. Empirical studies demographic consequences isolation are critical understand how populations persist through changing conditions. We used a 34-year and environmental dataset from population cooperatively breeding Florida Scrub-Jays (Aphelocoma coerulescens) create mechanistic models linking factors growth rates. found that has not declined despite both declining immigration increasing inbreeding, owing coinciding response in breeder survival. find evidence density-dependent immigration, survival fecundity, indicating interactions between vital rates local density play role buffering against change. Our study elucidates impacts demography long-term stability is maintained via responses.

Язык: Английский

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Explaining the divergence of population trajectories for two interacting waterfowl species

Ecological Monographs, Год журнала: 2025, Номер 95(1)

Опубликована: Янв. 12, 2025

Abstract Identifying the specific environmental features and associated density‐dependent processes that limit population growth is central to both ecology conservation. Comparative assessments of sympatric species allow for inference about how ecologically similar differentially respond their shared environment, which can be used inform community‐level conservation strategies. nevertheless complicated by interactions feedback loops among in question. We developed an integrated model based on 61 years ecological data describing demographic histories Canvasbacks ( Aythya valisineria ) Redheads americana ), two migratory diving ducks utilize breeding habitats affect each other's demography through interspecific nest parasitism. combined this with a transient life table response experiment determine extent rates, contributions growth, were between these species. found rates and, lesser extent, covaried Redheads, but trajectories abundances widely diverged during end twentieth century due inherent differences sensitivities variation harvest pressure. annual survival increased restrictive regulations; however, recent pressure female may contributing declines. Despite periodic, often dramatic, increases abundance wet years, number declined 13% whereas has 37% since 1961. Reductions improvements submerged aquatic vegetation throughout wintering grounds have mediated populations contracted dry Prairie Pothole Region. However, continued degradation climate‐related shifts wetland hydrology agricultural conversion surrounding grassland exceeded capacity compensation nonbreeding season.

Язык: Английский

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Population density and timing of breeding mediate effects of early life conditions on recruitment

Biology Letters, Год журнала: 2025, Номер 21(4)

Опубликована: Апрель 1, 2025

Identifying the factors driving juvenile recruitment is crucial for predicting response of populations to environmental change. Importantly, how early life conditions carry over influence may be highly dependent on context in which they occur. For example, effects challenging more pronounced under high densities or when young are born late season. We examined ecological influencing local spanning three decades Savannah sparrows ( Passerculus sandwichensis ) breeding Kent Island, NB, Canada. The effect nestling mass depended both population density and fledging date. At low-population season, had little probability. high-population later a stronger effect, with heavier individuals likely recruit. Lighter fledglings have lower due competitive ability, mobility greater susceptibility resource limitation relative fledglings. Our findings important implications life-history evolution selection body size changing world, highlighting relationships between density, timing offspring recruitment.

Язык: Английский

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Density‐dependent population dynamics of a high Arctic capital breeder, the barnacle goose

Journal of Animal Ecology, Год журнала: 2019, Номер 88(8), С. 1191 - 1201

Опубликована: Апрель 29, 2019

Density regulation of the population growth rate occurs through negative feedbacks on underlying vital rates, in response to increasing size. Here, we examine a capital breeder how rates different life-history stages, their elasticities and are affected by changes We developed an integrated model for local Svalbard barnacle geese, Branta leucopsis, using counts, reproductive data individual-based mark-recapture (1990-2017) age class-specific survival, reproduction number individuals. Based these estimates, quantified demographic structure effect size elasticities, as well rate. Local density at breeding grounds acted reduce effects reproduction; however, could not explain substantial variation survival although there was some support density-dependent first-year survival. With use prospective perturbation analysis projection matrix, show that changed increased. As approached carrying capacity, influence early-life reduced, whereas adult A retrospective revealed dependence resulted positive contribution numbers individuals class, realised The patterns this geese were from those recorded income birds, where mainly This indicates dynamics breeders, such goose, likely be more reproduction-driven than is case breeders.

Язык: Английский

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Quantifying the links between land use and population growth rate in a declining farmland bird

Ecology and Evolution, Год журнала: 2019, Номер 9(2), С. 868 - 879

Опубликована: Янв. 1, 2019

Abstract Land use is likely to be a key driver of population dynamics species inhabiting anthropogenic landscapes, such as farmlands. Understanding the relationships between land and variation in growth rates therefore critical for management many farmland species. Using 24 years data declining bird an integrated model, we examined how spatiotemporal (defined habitats with “Short” “Tall” ground vegetation during breeding season) habitat‐specific demographic parameters relates taking into account individual movements habitats. We also evaluated contributions using transient life table response experiments which gives information on contribution past real‐time elasticities suggests future scenarios change rates. LTRE analyses revealed clear Short annual rate that was mostly due fledgling recruitment, whereas there no evidence Tall Only 18% explained by modeled local demography, remaining being apparent immigration (i.e., residual variation). discuss potential biological methodological reasons high open populations. In line analysis, elasticity analysis linked had stronger influence than those Most particularly, increase proportion sites occupied Old breeders could have distinct positive impact growth. High‐quality grazed pastures been southern Sweden. Converting low‐quality high‐quality present negative trend this, other similar habitat requirements.

Язык: Английский

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