Combined Influences of Model Choice, Data Quality, and Data Quantity When Estimating Population Trends

Rueda‐Cediel, Pamela; Anderson, Kurt E.; Regan, Tracey J.; Franklin, Janet; Regan, Helen M.

doi:10.1371/journal.pone.0132255

Cited by 30 publications

(39 citation statements)

References 33 publications

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“…If this population trend is maintained, the probability of extinction within 100 years was estimated at 37%. Lengthening a time series improves the precision of the results and reduces the bias of the predicted population trend [39]. Although our estimate was based on a PVA using 10 years of count data, which is the minimum number of years required to undertake the analysis, and should therefore be considered with caution, some information useful for management may be derived from these results.…”

Section: Discussionmentioning

confidence: 99%

Population Abundance of the Endangered Galapagos Sea Lion Zalophus wollebaeki in the Southeastern Galapagos Archipelago

2017

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There is great concern regarding the population status of the endangered Galapagos sea lion (GSL) because it has drastically decreased over the last 30 years. We determined the population size and growth trend of the GSL in the Galapagos southeastern region (SER) at three population levels based on the available census data: 1) SER (2011–2015), including 13 rookeries on the four islands San Cristóbal (SC), Española, Floreana, and Santa Fe, comprising 58% of the archipelago’s population; 2) SC (2011–2015), including five rookeries, comprising 52% of the SER population; and 3) El Malecón (2005–2015), the largest rookery on SC and in the SER (43% of the population on SC and 22% in the SER). We also analyzed the influence of environmental variability on pup abundance in these rookeries. The current GSL population size in the SER, after applying correction factors to the counts, is estimated at approximately 2300–4100 individuals and has declined at an average annual rate (ʎ) of 8.7% over the last five years. A similar trend was determined for SC but at ʎ = 1.4% during the same period. For El Malecón, a count-based population viability analysis using a diffusion approximation approach showed that the population increased from 2005 to 2015 at ʎ = 2%. The interannual variability in pup abundance was associated with anomalies in sea surface temperature linked to oceanographic-atmospheric events, which impact the abundance and availability of prey, and ultimately may determine the population’s reproductive success. Since rookeries in the SER had different population trends, management actions should be implemented based on their specific conditions, giving priority to rookeries such as El Malecón, which, despite showing a slightly increasing population trend, still faces a high risk of extinction due to anthropogenic disturbances and environmental variability that may affect its growth and survival.

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Section: Discussionmentioning

confidence: 99%

Population Abundance of the Endangered Galapagos Sea Lion Zalophus wollebaeki in the Southeastern Galapagos Archipelago

2017

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“…The temporal extent of the data needs to be considered relative to the lifespan of the taxa of interest and the projection horizon (Zeigler et al 2013;Rueda-Cediel et al 2015), as well as the importance of infrequent catastrophes as determinants of population change (Ralls & Taylor 1997). The data period:projection horizon ratio was 0.01-0.23-1.2, meaning that in most cases the temporal extent of the data was much shorter than the period over which projections were being made.…”

Section: Parametrisation Datamentioning

confidence: 99%

“…GitHub) to help increase transparency and repeatability (see Wood et al 2017). (5) PVA should be based on as long and high-quality data as possible given the context the model is being developed and used in (Coulson et al 2001;Zeigler et al 2013;Rueda-Cediel et al 2015). We do not, however, advocate waiting indefinitely for the 'perfect' dataset, as not making any decision does carry a cost.…”

Section: Recommendationsmentioning

confidence: 99%

Population viability analyses in New Zealand: a review

Simpkins¹,

Lee²,

Powers³

et al. 2018

NZ J Ecol

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Biodiversity assets often require conservation management, which, in turn, necessitates decisions about which ecosystem, community or species should be prioritised to receive resources. Population viability analysis (PVA) uses a suite of quantitative methods to estimate the likelihood of population decline and extinction for a given species, and can be used to assess a population's status, providing useful information to decision-makers. In New Zealand, a range of taxa have been analysed using the PVA approach, but the scope of its implementation has not previously been reviewed. We compiled a database of 78 published PVAs for New Zealand indigenous fauna and flora, along with details of the species considered, the data used to parametrise the model, and the technical details of their implementation. We assessed the taxa and threat status of the species for which PVA were conducted relative to the distribution of taxa across threat classes in the New Zealand Threat Classification System database. There were clear biases in the species selected for analysis, notably an over-representation of birds and threatened species in general, and an under-representation of invertebrates and plants. Model parameterisation and implementation were often not reported in a transparent or standardised way, which hinders model communication and reconstruction. To maximise the benefit of PVAs, we suggest that more attention should be given to the ecosystem-level importance of species, and to species whose threat status is changing rapidly or are not yet threatened. More clearly describing the parameterisation, underlying assumptions and implementation of PVAs will help to better contextualise their results and support reproducible ecological science and decision-making.

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“…, Rueda‐Cediel et al. , Holmes ). Classification schemes such as the IUCN Red List must prescribe general rules for the categorisation of populations in order to achieve comparability and remain accessible, but in this generality they may miss population‐specific measures, leading to misrepresentative classification (Akçakaya et al.…”

Section: Introductionmentioning

confidence: 99%

Voluntary recording scheme reveals ongoing decline in the United Kingdom hazel dormouse Muscardinus avellanarius population

Goodwin

Hodgson

Al-Fulaij³

et al. 2017

Mammal Review

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In order to conserve threatened species, knowledge of the status, trends and trajectories of populations is required. Co‐ordinating collection of these data is challenging, especially for inconspicuous species such as the hazel dormouse Muscardinus avellanarius. The UK National Dormouse Monitoring Programme (NDMP) is comprised of nest box recording schemes organised by volunteers. The number, size, and coverage of these schemes has varied over time. Such changes risk conflation of genuine population trends with covarying artefacts, including survey effort and expansion into sites of variable quality. We provide a robust analysis of count data from 400 NDMP sites from 1993 to 2014 and demonstrate that changes in counts are not an artefact of survey characteristics. In relation to the International Union for Conservation of Nature (IUCN) Red List criteria, we conclude that dormouse counts in nest boxes are an index of abundance appropriate to the taxon and allow the inference of population reduction of 72% (95% confidence intervals 62–79%) over the 22 years from 1993 to 2014, equivalent to a mean annual rate of decline of 5.8% (4.5–7.1%). This decline is ongoing. We highlight difficulties in assigning an IUCN Red List conservation category to a population, given variation in apparent trends over consecutive time‐periods. In eight out of 13 sliding window intervals of 10 years from 1993 to 2014, the 95% confidence intervals overlap a decline of 50%. While average population decline over 10‐year periods suggests that the hazel dormouse should be classified as Vulnerable, a precautionary approach would not rule out the category of Endangered in the United Kingdom, given the lower bounds of population change estimates, the mean annual rate of decline and ongoing decline. Ongoing decline in the hazel dormouse population is despite a high level of species protection and widespread conservation measures. The hazel dormouse is a UK Biodiversity Action Plan Priority Species and a European Protected Species, and the causes of population reduction are not well understood and may not have ceased. An urgent appraisal of dormouse conservation is required to ensure the species’ favourable conservation status.

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Combined Influences of Model Choice, Data Quality, and Data Quantity When Estimating Population Trends

Cited by 30 publications

References 33 publications

Population Abundance of the Endangered Galapagos Sea Lion Zalophus wollebaeki in the Southeastern Galapagos Archipelago

Population Abundance of the Endangered Galapagos Sea Lion Zalophus wollebaeki in the Southeastern Galapagos Archipelago

Population viability analyses in New Zealand: a review

Voluntary recording scheme reveals ongoing decline in the United Kingdom hazel dormouse Muscardinus avellanarius population

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