Predicting reintroduction outcomes for highly vulnerable species that do not currently coexist with their key threats

Parlato, Elizabeth H.; Armstrong, Doug P.

doi:10.1111/cobi.13096

Cited by 8 publications

(8 citation statements)

References 40 publications

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“…Island translocations of small passerines in and around New Zealand are routine and managers are among leaders in the field of translocation science. For such species, source and release populations may be small but have been intensively monitored for several decades (e.g., Armstrong et al, 2017; Miskelly & Powlesland, 2013; Parlato & Armstrong, 2018). For those actively involved in management, any impact on source populations would, very reasonably, be considered negligible due to the history of sustainably harvesting from these populations.…”

Section: Discussionmentioning

confidence: 99%

Are we adequately assessing the demographic impacts of harvesting for wild‐sourced conservation translocations?

Mitchell

Boulton

Sunnucks

et al. 2021

Conservat Sci and Prac

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Translocation, the human‐mediated movement of organisms from one area to another, is a popular tool in conservation management. Wild‐caught individuals are more likely to persist following release than those sourced from captive breeding. However, this benefit of obtaining individuals from wild populations must be carefully weighed against the potential harm to the viability of source populations. In this structured review, we assess the peer‐reviewed primary literature that addresses wild‐sourced translocation programs. We aim to determine what proportion of studies make a priori estimates of the impact of harvesting on source populations, what proportion provide quantitative evidence of demographic trends in source populations following harvest, and which methods are being used to assess impacts of harvesting on source populations. Of 292 articles reviewed, we identified just 32 instances (11%) where impact on the source population was estimated. The proportion of studies that assess impacts on source populations in a given year has not increased over time. However, studies that make explicit a priori comparisons of alternative harvesting strategies are becoming more frequent. We propose a standardized framework for reporting on management of translocation source populations. Published summaries of wild‐sourced translocations should include clear conservation goals, a description of the methods used to assess potential impact, an a priori justification based on evidence for the chosen harvesting strategy, an estimated timeline for recovery and a summary of postremoval population trends to assess the efficacy of a priori impact assessment. Routinely reporting impacts of harvesting on source populations will inform management when source sustainability is uncertain, improve transparency and increase the likelihood of successful conservation for many threatened species.

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Section: Discussionmentioning

confidence: 99%

Are we adequately assessing the demographic impacts of harvesting for wild‐sourced conservation translocations?

Mitchell

Boulton

Sunnucks

et al. 2021

Conservat Sci and Prac

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“…This type of application has parallels with methods for inferring unobserved ecological processes using indicator or surrogate species (e.g. Wenger, 2008; Parlato and Armstrong, 2018; Fleming et al., 2020).…”

Section: Discussionmentioning

confidence: 99%

Incorporating data‐based estimates of temporal variation into projections for newly monitored populations

Parlato

Ewen

McCready

et al. 2021

Animal Conservation

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The importance of accounting for temporal variation in vital rates when modelling population dynamics is well recognized. However, long‐term (usually >5 years) datasets are needed to estimate this variation. Consequently, models for newly monitored populations typically assume no temporal variation or use default values provided in software programmes, both of which can give misleading inferences about population dynamics. The goal of this study is to improve estimation of dynamics in the initial years of conservation programmes by incorporating data‐based estimates of temporal variation from other populations with longer‐term data available. We show how data‐derived priors can be generated using estimates of temporal variation in vital rates from other populations, providing information about expected variation until sufficient population‐specific data are available. We specifically evaluated whether data‐derived priors improved our ability to estimate temporal variation for a reintroduced population monitored for 3 years postrelease. We first predicted population growth and probability of extinction assuming no temporal variation in vital rates, then compared projections to those obtained when temporal variation was estimated with uniform priors or with the data‐derived priors. Both types of priors were constrained to plausible ranges, and we also assessed sensitivity of model outputs to widening those ranges. Median projected population size was similar under all three models, but extinction probability was higher with inclusion of temporal variability, reiterating the importance of incorporating this source of uncertainty. Projections with temporal variation were similar irrespective of whether data‐derived priors or uniform priors were used. However, the data‐derived priors generated more precise estimates of annual variation that were less sensitive to relaxation of prior constraints. The approach we present can facilitate management decisions at the outset of conservation programmes when risk assessments that account for all relevant uncertainties can be crucial for determining optimal management strategies.

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“…This approach allowed us to use all available information to estimate population size for years with data and infer population size for years without. Finally, we stochastically estimated the average finite rate of population growth

λ

at the source site following Parlato and Armstrong (2018):

λ goodbreak= \frac{φ_{ad} + \sqrt{{φ_{italicad}}^{2} + 4 P_{fem} italicfγ {φ_{italicjuv}}^{2}}}{2} .

…”

Section: Methodsmentioning

confidence: 99%

“…This trade‐off can sometimes be solved by establishing captive populations that become sources for translocations, but captivity is not an option for every species (Canessa, Converse, et al, 2016). Identifying the appropriate number of individuals to translocate to a wild site is complicated because the optimal numbers depend on the vital rates expected at the destination sites and those rates are highly uncertain for translocations involving endangered species (Parlato & Armstrong, 2018). It is therefore essential for translocation planning to be able to forecast both the demographic impacts on source populations and the establishment of destination populations in face of uncertainty (IUCN, 2013; Panfylova et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Predicting harvest impact and establishment success when translocating highly mobile and endangered species

Wittmer

Kenup

et al. 2022

Journal of Applied Ecology

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Harvesting individuals for translocations can negatively impact source populations, a critical challenge for species reduced to small populations. Consequently, translocation cohorts often remain small, reducing the establishment probability at the destination. Balancing the potential benefits and risks of such translocations is further complicated by philopatry and natural metapopulation dynamics if the target species is highly mobile. These challenges highlight the importance of translocation feasibility assessments, but such assessments often remain qualitative to date. The critically endangered Kuaka (Whenua Hou Diving Petrel; Pelecanoides whenuahouensis) is a philopatric, highly mobile seabird that could benefit from conservation translocations, but only one small population remains. Through expert elicitations with a user‐friendly Shiny app, we developed a novel metapopulation extension to an integrated population model fitted to long‐term data, allowing us to simultaneously project harvest impact on the source and establishment of destination populations under alternative translocation scenarios, while accounting for philopatry and metapopulation dynamics. Establishment of a destination population without excessive impact on the source was possible, but subject to uncertainty about philopatry and metapopulation dynamics. Accounting for juveniles returning to the source post‐translocations reduced impact on the source, but also decreased establishment at the destination. Natural movements of adults and juveniles between source and destination populations were predicted to modulate effects of different harvest intensities. Synthesis and application. Using state‐of‐the art integrated population models and expert elicitations, we illustrate how translocation feasibility can be evaluated transparently and quantitatively, even when targeting endangered, philopatric and highly mobile species. Our approach is a considerable improvement on current qualitative feasibility assessments. However, we also illustrate that, ultimately, the favoured translocation strategy depends on balancing biological and other fundamental objectives inherent to translocations. Therefore, the ideal strategy cannot be determined solely mathematically, and feasibility assessments should incorporate explicit value statements. Our methodology is applicable to any future translocation scenario.

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Predicting reintroduction outcomes for highly vulnerable species that do not currently coexist with their key threats

Cited by 8 publications

References 40 publications

Are we adequately assessing the demographic impacts of harvesting for wild‐sourced conservation translocations?

Are we adequately assessing the demographic impacts of harvesting for wild‐sourced conservation translocations?

Incorporating data‐based estimates of temporal variation into projections for newly monitored populations

Predicting harvest impact and establishment success when translocating highly mobile and endangered species

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