Optimal design of butterfly occupancy surveys and testing if occupancy converts to abundance for sparse populations

Bried, Jason T.; Pellet, Jérôme

doi:10.1007/s10841-011-9435-2

Cited by 32 publications

(21 citation statements)

References 66 publications

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“…Therefore, higher levels of survey effort are often recommended for rare species (e.g. Bried and Pellet 2012). In summary, we demonstrated a useful sampling protocol for assessing broad diversity patterns of relatively abundant species in response to environmental gradients (Vellend et al 2008).…”

Section: Discussionmentioning

confidence: 80%

Developing robust field survey protocols in landscape ecology: a case study on birds, plants and butterflies

et al. 2014

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Sustainable land management requires scientists to provide reliable data on diversity distribution patterns. Resource restrictions limit the affordable sampling effort, both with respect to number of survey sites and amount of effort per site. We compared different levels of survey effort in a case study in Central Romania, varying the number of repeats per site and number of survey sites. Target taxa were plants, birds and butterflies. For plants, we surveyed three 10 m 2 plots and ten plots of 1 m 2 at each site. For birds, we used point counts and for butterflies Pollard walks, in both cases with four repeats. We fitted hierarchical community models to estimate true species richness per site. Estimates of true species richness per site strongly correlated with observed species richness. However, hierarchical community models yielded unrealistically high estimates of true species richness per site, hence we used observed richness for further analyses. For each species group, we compared diversity indices from subsets of the dataset with the full dataset. Findings obtained with a reduced survey effort reflected well those obtained with full effort. Moreover, we conducted a power analysis to assess how the number of survey sites affected the minimum detectable effect of landscape heterogeneity on species richness, and found there was an exponential decrease in the minimum detectable effect with increasing number of sites. In combination, our findings suggest that assessing broad 123Biodivers Conserv (2015) 24:33-46 DOI 10.1007 diversity patterns in abundant and readily detectable organisms may be possible with relatively low survey effort per site. Our study demonstrates the utility of conducting pilot studies prior to designing large-scale studies on diversity distribution patterns.

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Section: Discussionmentioning

confidence: 80%

Developing robust field survey protocols in landscape ecology: a case study on birds, plants and butterflies

et al. 2014

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“…While patch area and previous occupancy as surrogates for population size can suffice for predicting average occupancy -and thus average abundance -predictions of yearly changes in occupancy ignorant of population sizes would be biased towards the average case. But trying to predict extinction dynamics of individual populations and estimate actual, not average, abundances using the same models could lead to biased estimates and higher uncertainty (Harrison et al 2011, Bried andPellet 2012). Generally, this calls for caution when using occupancy as a surrogate for abundance in some contexts.…”

Section: Effect Of Abundance On Occupancymentioning

confidence: 99%

Long‐term demographic surveys reveal a consistent relationship between average occupancy and abundance within local populations of a butterfly metapopulation

2019

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Species distribution models are the tool of choice for large-scale population monitoring, environmental association studies and predictions of range shifts under future environmental conditions. Available data and familiarity of the tools rather than the underlying population dynamics often dictate the choice of specific methodespecially for the case of presence-absence data. Yet, for predictive purposes, the relationship between occupancy and abundance embodied in the models should reflect the actual population dynamics of the modelled species. To understand the relationship of occupancy and abundance in a heterogeneous landscape at the scale of local populations, we built a spatio-temporal regression model of populations of the Glanville fritillary butterfly Melitaea cinxia in a Baltic Sea archipelago. Our data comprised nineteen years of habitat surveys and snapshot data of land use in the region. We used variance partitioning to quantify relative contributions of land use, habitat quality and metapopulation covariates. The model revealed a consistent and positive, but noisy relationship between average occupancy and mean abundance in local populations. Patterns of abundance were highly variable across years, with large uncorrelated random variation and strong local population stochasticity. In contrast, the spatio-temporal random effect, habitat quality, population connectivity and patch size explained variation in occupancy, vindicating metapopulation theory as the basis for modelling occupancy patterns in fragmented landscapes. Previous abundance was an important predictor in the occupancy model, which points to a spillover of abundance into occupancy dynamics. While occupancy models can successfully model large-scale population structure and average occupancy, extinction probability estimates for local populations derived from occupancy-only models are overconfident, as extinction risk is dependent on actual, not average, abundance. Long-term demographic surveys reveal a consistent relationship between average occupancy and abundance within local populations of a butterfly metapopulation Torsti Schulz, Jarno Vanhatalo and Marjo Saastamoinen T. Schulz (https://orcid.org/0000-0001-8940-9483) ✉ (torsti.schulz@helsinki.fi), J. Vanhatalo (https://orcid.org/0000-0002-6831-0211) and M. Saastamoinen (https://orcid.org/0000-0001-7009-2527),

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“…Bried and Pellet 2012;LaCommare et al 2012;Williams and Thomas 2009). In many cases, the relationship between them is unknown and consequently a linear relationship must be assumed (LaCommare et al 2012).…”

Section: Discussionmentioning

confidence: 99%

“…Bried and Pellet (2012) concluded that the minimum allowable effort for occupancy monitoring of the Karner blue butterfly was 360 (40 sites x 9 surveys) for the spring generation and 200 (20 sites x 10 surveys) for the summer generation. Keizer-Vlek et al (2012) found that more than 1000 sites must be sampled to detect a 40% change in the frequency for monitoring rare river inhabiting macroinvertebrates (50 sites for common species).…”

Section: Discussionmentioning

confidence: 99%

“…Jones et al 2015;Steenweg et al 2016;Williams and Thomas 2009). Unfortunately, only a few power analysis studies on the populations trends of terrestrial invertebrates have been published in the peer reviewed literature (Bried and Pellet 2012;Lang et al 2016;Schmucki et al 2016, all on butterflies). Consequently, the possibility of adequately monitoring the population trends of invertebrates in general and elusive invertebrates in particular has hardly been evaluated.…”

Section: Introductionmentioning

confidence: 99%

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Can we successfully monitor a population density decline of elusive invertebrates? A statistical power analysis on Lucanus cervus

Thomaes¹,

Verschelde²,

Mader³

et al. 2017

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Monitoring global biodiversity is essential for understanding and countering its current loss. However, monitoring of many species is hindered by their difficult detection due to crepuscular activity, hidden phases of the life cycle, short activity period and low population density. Few statistical power analyses of declining trends have been published for terrestrial invertebrates. Consequently, no knowledge exists of the success rate of monitoring elusive invertebrates. Here data from monitoring transects of the European stag beetle, Lucanus cervus, is used to investigate whether the population trend of this elusive species can be adequately monitored. Data from studies in UK, Switzerland and Germany were compiled to parameterize a simulation model explaining the stag beetle abundance as a function of temperature and seasonality. A Monte-Carlo simulation was used to evaluate the effort needed to detect a population abundance decline of 1%/year over a period of 12 years. To reveal such a decline, at least 240 1-hour transect walks on 40 to 100 transects need to be implemented in weekly intervals during warm evenings. It is concluded that monitoring of stag beetles is feasible and the effort is not greater than that which has been found for other invertebrates. Based on this example, it is assumed that many other elusive species with similar life history traits can be monitored with moderate efforts. As saproxylic invertebrates account for a large share of the forest biodiversity, although many are elusive, it is proposed that at least some flagship species are included in monitoring programmes.

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Optimal design of butterfly occupancy surveys and testing if occupancy converts to abundance for sparse populations

Cited by 32 publications

References 66 publications

Developing robust field survey protocols in landscape ecology: a case study on birds, plants and butterflies

Developing robust field survey protocols in landscape ecology: a case study on birds, plants and butterflies

Long‐term demographic surveys reveal a consistent relationship between average occupancy and abundance within local populations of a butterfly metapopulation

Can we successfully monitor a population density decline of elusive invertebrates? A statistical power analysis on Lucanus cervus

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