Ninety years of change, from commercial extinction to recovery, range expansion and decline for Antarctic fur seals at South Georgia

Global Change Biology, Journal Year: 2023, Volume and Issue: 29(24), P. 6867 - 6887

Published: Oct. 15, 2023

With environmental change, understanding how species recover from overharvesting and maintain viable populations is central to ecosystem restoration. Here, we reconstruct 90 years of recovery trajectory the Antarctic fur seal at South Georgia (S.W. Atlantic), a key indicator in krill-based food webs Southern Ocean. After being harvested commercial extinction by 1907, this population rebounded now constitutes most abundant otariid World. However, its status remains uncertain due insufficient conflicting data, anthropogenic pressures affecting krill, an essential staple for millions seals other predators. Using integrated models, estimated simultaneously long-term abundance Bird Island, northwest Georgia, epicentre after sealing, adjustments survey counts with spatiotemporal applicability. Applied latest comprehensive 2007-2009 as 3,510,283 [95% CI: 3,140,548-3,919,604] (ca. 98% global population), 40 maximum growth range expansion owing krill supply. At 50 exponential followed 25 slow stable growth, collapsed 2009 has thereafter declined -7.2% [-5.2, -9.1] per annum, levels 1970s. For instrumental record, correlates time-varying relationship between coupled climate sea surface temperature cycles associated low regional availability, although effects increasing extraction fishing natural competitors remain uncertain. Since 2015, longevity recruitment have dropped, sexual maturation retarded, expected mostly negative highly variable. Our analysis documents rise fall Ocean predator over century profound change.

Language: Английский

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Local population collapse of Ross's and lesser snow geese driven by failing recruitment and diminished philopatry

Oikos, Journal Year: 2022, Volume and Issue: 2022(5)

Published: March 3, 2022

Dynamics of free‐ranging animal populations can result from complex interplays survival, recruitment and movement. Yet incomplete understanding demography impedes conservation strategies intended to modify population dynamics focal species. We estimated survival per capita production young, as well emigration immigration, 1997 2017 in Ross's goose Anser rossii lesser snow caerulescens , which are sympatric species migratory birds that nest the central Canadian Arctic at one largest breeding colonies North America. formed age‐structured integrated models (IPMs) for each jointly analyzed live dead encounter data adult size fecundity understand drivers dynamics. compared between because both increased during 1990s early 2000s yet thereafter geese declined, while continued increase, then stabilized similarly declined. Declines were caused by reduced juvenile emigration. Stronger declines explain their earlier decline geese. Despite divergence trends geese, we found strong synchrony demographic rates suggested substantial this colony similar responses environmental conditions. Direct estimation patterns IPM framework permitted hypothesis testing inference about role even though immigrant sources unsampled. provide a novel m‐array implementation specific multi‐state Burnham model greatly improved computational efficiency convergence posterior estimates. Our findings an important reminder permanent movements play metapopulation structure.

Language: Английский

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Efficient use of harvest data: a size‐class‐structured integrated population model for exploited populations

Ecography, Journal Year: 2021, Volume and Issue: 44(9), P. 1296 - 1310

Published: June 14, 2021

Many animal populations are subject to hunting or fishing in the wild. Detailed knowledge of demographic parameters (e.g. survival, reproduction) and temporal dynamics such is crucial for sustainable management. Despite their relevance management decisions, structure size exploited often not known, data limited. Recently, joint analysis different types data, as population counts, reproductive capture–mark–recapture within integrated models (IPMs) has gained much popularity it may allow estimating structure, well key rates, while fully accounting uncertainty. IPMs built so far have typically been age‐structured models. However, age harvested individuals usually difficult and/or costly assess therefore available. Here, we introduce an IPM structured by body classes, which allows making efficient use commonly available accurate information on missing. The model jointly analyzes size‐at‐harvest capture–mark–recapture–recovery reproduction from necropsies, illustrate its applicability a case study involving heavily hunted wild boar. This species increased abundance over last decades despite intense harvest, provides insights into roles natural mortality, growth, maturation schedules output compensating loss hunting. Early high contributed boar persistence strong pressure. We thus demonstrate potential size‐class‐structured tools investigate with limited age, highlight both this framework other follow‐up analyses highly relevant

Language: Английский

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Integrated Population Models: Achieving Their Potential

Journal of Statistical Theory and Practice, Journal Year: 2022, Volume and Issue: 17(1)

Published: Nov. 15, 2022

Abstract Precise and accurate estimates of abundance demographic rates are primary quantities interest within wildlife conservation management. Such provide insight into population trends over time the associated underlying ecological drivers systems. This information is fundamental in managing ecosystems, assessing species status developing implementing effective policy. Observational monitoring data typically collected on populations using an array different survey protocols, dependent questions interest. For each these designs, a range advanced statistical techniques have been developed which well understood. However, often multiple types may exist for same under study. Analyzing set separately implicitly discards common contained other sets. An alternative approach that aims to optimize shared sets use “model-based integration” approach, or more commonly referred as “integrated model.” integrated modeling simultaneously analyzes all available single, robust, framework. paper provides overview models, with focus models (IPMs) include Four main challenges this area discussed, namely model specification, computational aspects, assessment forecasting. should encourage researchers explore further develop new practical tools ensure full utility can be made IPMs future studies.

Language: Английский

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Interrelated impacts of climate and land‐use change on a widespread waterbird

Journal of Animal Ecology, Journal Year: 2021, Volume and Issue: 90(5), P. 1165 - 1176

Published: March 22, 2021

Abstract Together climate and land‐use change play a crucial role in determining species distribution abundance, but measuring the simultaneous impacts of these processes on current future population trajectories is challenging due to time lags, interactive effects data limitations. Most approaches that relate multiple global drivers changes have been based occurrence or count alone. We leveraged three long‐term (1995–2019) datasets develop coupled integrated model‐Bayesian viability analysis (IPM‐BPVA) project survival reproductive success for common loons Gavia immer northern Wisconsin, USA, by explicitly linking vital rates land use. The winter North Atlantic Oscillation (NAO), broad‐scale index, immediately preceding breeding season annual developed cover within areas both had strongly negative influences adult survival. Local summer rainfall was negatively related fecundity, though this relationship mediated lagged interaction with NAO, suggesting compensatory population‐level response variability. compared under 12 scenarios change, precipitation NAO conditions. Under all scenarios, loon expected decline, yet steepest declines were projected positive trends, as anticipated ongoing change. Thus, United States are likely remain affected climatic occurring thousands miles away during non‐breeding period cycle. Our results reveal differentially contributing along southern edge their range will continue do so despite natural responses. also demonstrate concurrent types facilitates deeper understanding ecological implications anthropogenic‐induced at spatial scales. modelling approach can be used demographic responses populations varying environmental conditions while accounting sources uncertainty, an increasingly pressing need face unprecedented

Language: Английский

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Consequences of violating assumptions of integrated population models on parameter estimates

Environmental and Ecological Statistics, Journal Year: 2021, Volume and Issue: 28(3), P. 667 - 695

Published: July 1, 2021

Abstract While ecologists know that models require assumptions, the consequences of their violation become vague as model complexity increases. Integrated population (IPMs) combine several datasets to inform a and estimate survival reproduction parameters jointly with higher precision than is possible using independent models. However, accuracy actually depends on an adequate fit datasets. We first investigated bias obtained from integrated when specific assumptions are violated. For instance, may assume all females reproduce although there non-breeding in population. Our second goal was identify which diagnostic tests sensitive detect violations IPMs. simulated data mimicking short- long-lived species under five scenarios assumption each scenario, we fitted IPM violates (simple IPM) does not violate assumption. estimated uncertainty performed seven assess data. results show simple quite robust many only resulted small parameter estimates. Yet, applied were such bias. The some absence immigrants larger more sensitive. informed by least amount most biased scenarios. provide guidelines misspecified diagnose being Simple should often be sufficient describe dynamics, abundant, complex accounting for processes will able shed light biological questions.

Language: Английский

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Reconstructing population dynamics of a threatened marine mammal using multiple data sets

Scientific Reports, Journal Year: 2021, Volume and Issue: 11(1)

Published: Jan. 29, 2021

Abstract Models of marine mammal population dynamics have been used extensively to predict abundance. A less common application these models is reconstruct historical dynamics, filling in gaps observation data by integrating information from multiple sources. We developed an integrated model for the Florida manatee ( Trichechus manatus latirostris ) its southwest region state over past 20 years. Our improved precision key parameter estimates and permitted inference on poorly known parameters. Population growth was slow (averaging 1.02; 95% credible interval 1.01–1.03) but not steady, unusual mortality event 2013 led estimated net loss 332 (217–466) manatees. analyses showed that precise abundance could be derived vital rates a few input abundance, which may mean costly surveys estimate don’t need conducted as frequently. study also shows retrospective can useful to: (1) transient age distribution; (2) assess communicate conservation status wild populations; (3) improve our understanding environmental effects thus enhance ability forecast.

Language: Английский

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Habitat-use influences severe disease-mediated population declines in two of the most common garden bird species in Great Britain

Scientific Reports, Journal Year: 2022, Volume and Issue: 12(1)

Published: Sept. 5, 2022

Abstract The influence of supplementary feeding wildlife on disease transmission and its consequent impacts population dynamics are underappreciated. In Great Britain, is hypothesised to have enabled the spread protozoan parasite, Trichomonas gallinae , from columbids finches, leading epidemic finch trichomonosis a rapid decline greenfinch ( Chloris chloris ). More recently, chaffinch Fringilla coelebs ), has also declined markedly second fifth commonest bird in Britain. Using citizen science data, we show that both declines were driven primarily by reduced adult survival, with greatest reductions occurring peri-domestic habitats, where food provision common. Post-mortem examinations showed proportional increase cases, near-contemporaneous decline. Like greenfinches, chaffinches often use food, but less associated human habitation. Our results support hypothesis can parasite frequency within between common species. However, behind resultant change vary markedly, highlighting need for integrating surveillance demographic monitoring. Other species susceptible T. infection may be at risk. Supplementary guidelines should include mitigation strategies ensure benefits target outweigh risks.

Language: Английский

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Breeding season management is unlikely to improve population viability of a data-deficient migratory species in decline

Biological Conservation, Journal Year: 2023, Volume and Issue: 283, P. 110104 - 110104

Published: May 12, 2023

Language: Английский

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A multispecies hierarchical model to integrate count and distance‐sampling data

Ecology, Journal Year: 2024, Volume and Issue: 105(7)

Published: June 6, 2024

Abstract Integrated community models—an emerging framework in which multiple data sources for species are analyzed simultaneously—offer opportunities to expand inferences beyond the single‐species and single‐data‐source approaches common ecology. We developed a novel integrated model that combines distance sampling single‐visit count data; within model, information is shared among (via joint likelihood) random‐effects structure) estimate abundance patterns across community. Parameters relating between sources, can specify either or separate observation processes each source. Simulations demonstrated provided unbiased estimates of detection parameters even when probabilities varied types. The also more accurate precise parameter than alternative models many instances. applied 11 herbivore Masai Mara National Reserve, Kenya, found considerable interspecific variation response local wildlife management practices: Five showed higher abundances region with passive conservation enforcement (median species: 4.5× higher), three active (median: 3.9× remaining no differences two regions. Furthermore, average was slightly but not definitively so (posterior mean: by 0.20 animals; 95% credible interval: 1.43 fewer animals, 1.86 animals). Our modeling has potential scope inference over space, time, levels biological organization, practitioners should carefully evaluate whether assumptions met their systems integration valuable applications.

Language: Английский

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