Differential contribution of demographic rate synchrony to population synchrony in barn swallows

Schaub, Michael; Hirschheydt, Johann von; Grüebler, Martin U.

doi:10.1111/1365-2656.12423

Cited by 38 publications

(53 citation statements)

References 58 publications

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“…), examine spatiotemporal demography (Schaub et al. ), or assess the community dynamics of interacting species (Péron and Koons ). Integrated analyses cannot guarantee improved inference, however, and as is always the case, careful thought and testing of assumptions must be practiced in order to construct useful and unbiased models (Abadi et al.…”

Section: Discussionmentioning

confidence: 99%

Understanding the demographic drivers of realized population growth rates

Koons

Arnold

Schaub

2017

Ecological Applications

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133

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Identifying the demographic parameters (e.g., reproduction, survival, dispersal) that most influence population dynamics can increase conservation effectiveness and enhance ecological understanding. Life table response experiments (LTRE) aim to decompose the effects of change in parameters on past demographic outcomes (e.g., population growth rates). But the vast majority of LTREs and other retrospective population analyses have focused on decomposing asymptotic population growth rates, which do not account for the dynamic interplay between population structure and vital rates that shape realized population growth rates (λt=Nt+1/Nt) in time-varying environments. We provide an empirical means to overcome these shortcomings by merging recently developed "transient life-table response experiments" with integrated population models (IPMs). IPMs allow for the estimation of latent population structure and other demographic parameters that are required for transient LTRE analysis, and Bayesian versions additionally allow for complete error propagation from the estimation of demographic parameters to derivations of realized population growth rates and perturbation analyses of growth rates. By integrating available monitoring data for Lesser Scaup over 60 yr, and conducting transient LTREs on IPM estimates, we found that the contribution of juvenile female survival to long-term variation in realized population growth rates was 1.6 and 3.7 times larger than that of adult female survival and fecundity, respectively. But a persistent long-term decline in fecundity explained 92% of the decline in abundance between 1983 and 2006. In contrast, an improvement in adult female survival drove the modest recovery in Lesser Scaup abundance since 2006, indicating that the most important demographic drivers of Lesser Scaup population dynamics are temporally dynamic. In addition to resolving uncertainty about Lesser Scaup population dynamics, the merger of IPMs with transient LTREs will strengthen our understanding of demography for many species as we aim to conserve biodiversity during an era of non-stationary global change.

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Section: Discussionmentioning

confidence: 99%

Understanding the demographic drivers of realized population growth rates

Koons

Arnold

Schaub

2017

Ecological Applications

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133

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“…We modelled the observation process as a normal distribution conditional on the state process:

y_{t} \sim Normal false(N_{1, t} + N_{normalad, t} + N_{normalim, t}, τ_{obs} false)

where y t is the number of observed breeding pairs in year t and τ obs is the sampling error or variance in annual detection probabilities. To estimate apparent survival probabilities from individual mark–resight data, we used a Cormack–Jolly–Seber open‐population live‐recapture formulation (Kéry & Schaub, ; Schaub, von Hirschheydt, & Grüebler, ). We estimated survival probabilities by assuming that annual survival during the first year of life (Φ juv, t ) was different from annual survival for birds older than 1 year (Φ ad, t ).…”

Section: Methodsmentioning

confidence: 99%

Evaluating population viability and efficacy of conservation management using integrated population models

Saunders

Cuthbert

Zipkin

2018

Journal of Applied Ecology

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Predicting population responses to environmental conditions or management scenarios is a fundamental challenge for conservation. Proper consideration of demographic, environmental and parameter uncertainties is essential for projecting population trends and optimal conservation strategies. We developed a coupled integrated population model‐Bayesian population viability analysis to assess the (1) impact of demographic rates (survival, fecundity, immigration) on past population dynamics; (2) population viability 10 years into the future; and (3) efficacy of possible management strategies for the federally endangered Great Lakes piping plover Charadrius melodus population. Our model synthesizes long‐term population survey, nest monitoring and mark–resight data, while accounting for multiple sources of uncertainty. We incorporated latent abundance of eastern North American merlins Falco columbarius, a primary predator of adult plovers, as a covariate on adult survival via a parallel state‐space model, accounting for the influence of an imperfectly observed process (i.e. predation pressure) on population viability. Mean plover abundance increased from 18 pairs in 1993 to 75 pairs in 2016, but annual population growth (λ¯t) was projected to be 0.95 (95% CI 0.72–1.12), suggesting a potential decline to 67 pairs within 10 years. Without accounting for an expanding merlin population, we would have concluded that the plover population was projected to increase (λ¯t = 1.02; 95% CI 0.94–1.09) to 91 pairs by 2026. We compared four conservation scenarios: (1) no proposed management; (2) increased control of chick predators (e.g. Corvidae, Laridae, mammals); (3) increased merlin control; and (4) simultaneous chick predator and merlin control. Compared to the null scenario, chick predator control reduced quasi‐extinction probability from 11.9% to 8.7%, merlin control more than halved (3.5%) the probability and simultaneous control reduced quasi‐extinction probability to 2.6%. Synthesis and applications. Piping plover recovery actions should consider systematic predator control, rather than current ad hoc protocols, especially given the predicted increase in regional merlin abundance. This approach of combining integrated population models with Bayesian population viability analysis to identify limiting components of the population cycle and evaluate alternative management strategies for conservation decision‐making shows great utility for aiding recovery of threatened populations.

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“…Therefore, we instead evaluated fit of the CJS and Poisson models to the individual CR and reproductive success data sets52. Fit of the CJS model was evaluated using the Freeman-Tukey statistic53 and fit of the Poisson model was evaluated using the Chi-square discrepancy measure.…”

Section: Methodsmentioning

confidence: 99%

Winter temperatures limit population growth rate of a migratory songbird

et al. 2017

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Understanding the factors that limit and regulate wildlife populations requires insight into demographic and environmental processes acting throughout the annual cycle. Here, we combine multi-year tracking data of individual birds with a 26-year demographic study of a migratory songbird to evaluate the relative effects of density and weather at the breeding and wintering grounds on population growth rate. Our results reveal clear support for opposing forces of winter temperature and breeding density driving population dynamics. Above-average temperatures at the wintering grounds lead to higher population growth, primarily through their strong positive effects on survival. However, population growth is regulated over the long term by strong negative effects of breeding density on both fecundity and adult male survival. Such knowledge of how year-round factors influence population growth, and the demographic mechanisms through which they act, will vastly improve our ability to predict species responses to environmental change and develop effective conservation strategies for migratory animals.

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Differential contribution of demographic rate synchrony to population synchrony in barn swallows

Cited by 38 publications

References 58 publications

Understanding the demographic drivers of realized population growth rates

Understanding the demographic drivers of realized population growth rates

Evaluating population viability and efficacy of conservation management using integrated population models

Winter temperatures limit population growth rate of a migratory songbird

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