Too few data and not enough time: approaches to detecting Allee effects in threatened species

Gilroy, James J.; Virzi, Thomas; Boulton, Rebecca L.; Lockwood, Julie L.

doi:10.1111/j.1755-263x.2012.00245.x

Cited by 16 publications

(17 citation statements)

References 33 publications

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“…However, although the Allee effect may increase individual fitness while the colony is growing, it may also have a reverse effect when the colony is decreasing, thus accelerating the decline. Therefore, investigating the presence of such an effect is important, especially when studying species of special conservation concern (Gilroy et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Factors driving population recovery of the greater horseshoe bat (Rhinolophus ferrumequinum) in the UK: implications for conservation

et al. 2017

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Although populations of many bat species appear to be recovering in some European countries, the extrinsic and intrinsic factors driving these increases have not yet been assessed. Disentangling the benefits of conservation management from other factors such as climate change is a crucial step for improving evidence-based conservation strategies. We used the greater horseshoe bat (Rhinolophus ferrumequinum) as a case study for understanding the recovery of bat populations, as its north-western populations have increased substantially over the past two decades following severe population declines. Using summer roost count data from the UK National Bat Monitoring Programme spanning an 18 year period from 1997 to 2014, we investigated the effects of (i) landscape characteristics associated with the implementation of the agri-environment schemes on colony trends and size, and (ii) meteorological variables on annual colony growth rate. We also assessed the relationship between colony size and colony growth to investigate intrinsic factors such as an Allee effect. Our results indicated that colony size was positively related to a range of landscape features (e.g. amount of broadleaf woodland and grassland, and density of linear features) surrounding the roost, while the amount of artificial light at night had a significant negative effect. Spring temperatures and precipitation (the latter with a lag of one year) were associated with annual colony growth. We also identified a negative density-dependence effect within colonies. Though the conservation of essential landscape elements may have contributed to population increases in the long-term, we conclude that recent population recovery has also been driven by climate Communicated by Dirk Sven Schmeller.Electronic supplementary material The online version of this article (doi:10.1007/s10531-017-1320-1) contains supplementary material, which is available to authorized users. change. Finally we recommend that the conservation of photophobic bat species such as R. ferrumequinum should focus on both the improvement of foraging/commuting habitats and the creation of dark areas.

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Section: Introductionmentioning

confidence: 99%

Factors driving population recovery of the greater horseshoe bat (Rhinolophus ferrumequinum) in the UK: implications for conservation

et al. 2017

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“…Failure to detect dynamics accurately can lead to overoptimistic assessments of how populations are faring, which can have disastrous consequences for management (Gilroy et al, 2012). In many tropical conservation settings, population census efforts are severely restricted due to underfunding or insufficient personnel and resources.…”

Section: Discussionmentioning

confidence: 99%

Optimal sampling frequency and timing of threatened tropical bird populations: A modeling approach

Banks

Rinnovatore

et al. 2015

Ecological Modelling

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a b s t r a c tConservation of threatened or endangered species relies critically on accurate population counts over time. In practice, many population censuses are conducted by non-governmental organizations or volunteer citizen scientists who are constrained by fiscal and temporal resources. Less than optimal sampling regimens (characterized by infrequent and/or irregular schedules) for conducting population censuses can result in woefully misleading population estimates -and thus have dire consequences for management and conservation. We illustrate this using an East African case study in which 14 years of bird data was collected in the Arabuko-Sokoke Forest in coastal Kenya. We first estimate life history parameters in a discrete matrix model. Desiring a data collection protocol which would lessen observation error and lend to a deeper understanding of population projections and dynamics of a threatened species, we carry out mathematical and statistical modeling efforts with an adaptation of a Leslie model for simulated population estimates stemming from different population sampling schemes. We illustrate how resource managers might take a strategic approach, using simple quantitative models, to develop an optimal sampling scheme that considers important species traits, such as breeding season, and balances the tradeoff between resources and accuracy.

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“…The generally poor availability and reliability of empirical data on the ecology and demography of threatened species is a pervasive constraint on effective decision-making [ 37 – 39 ]. Therefore, the use of expert opinion to supplement available data, as reported here, is relatively widespread but incorporates significant uncertainty [ 25 ].…”

Section: Discussionmentioning

confidence: 99%

A large-scale application of project prioritization to threatened species investment by a government agency

et al. 2018

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In a global environment of increasing species extinctions and decreasing availability of funds with which to combat the causes of biodiversity loss, maximising the efficiency of conservation efforts is crucial. The only way to ensure maximum return on conservation investment is to incorporate the cost, benefit and likelihood of success of conservation actions into decision-making in a systematic and objective way. Here we report on the application of a Project Prioritization Protocol (PPP), first implemented by the New Zealand Government, to target and prioritize investment in threatened species in New South Wales, Australia, under the state’s new Saving our Species program. Detailed management prescriptions for 368 threatened species were developed via an expert elicitation process, and were then prioritized using quantitative data on benefit, likelihood of success and implementation cost, and a simple cost-efficiency equation. We discuss the outcomes that have been realized even in the early stages of the program; including the efficient development of planning resources made available to all potential threatened species investors and the demonstration of a transparent and objective approach to threatened species management that will significantly increase the probability of meeting an objective to secure the greatest number of threatened species from extinction.

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Too few data and not enough time: approaches to detecting Allee effects in threatened species

Cited by 16 publications

References 33 publications

Factors driving population recovery of the greater horseshoe bat (Rhinolophus ferrumequinum) in the UK: implications for conservation

Factors driving population recovery of the greater horseshoe bat (Rhinolophus ferrumequinum) in the UK: implications for conservation

Optimal sampling frequency and timing of threatened tropical bird populations: A modeling approach

A large-scale application of project prioritization to threatened species investment by a government agency

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