A simulation study of the use of temporal occupancy for identifying core and transient species

Abstract

Transient species, which do not maintain self-sustaining populations in a system where they are observed, are ubiquitous in nature and their presence often impacts the interpretation of ecological patterns and processes. Identifying transient species from temporal occupancy, the proportion of time a species is observed at a given site over a time series, is subject to classification errors as a result of imperfect detection and source-sink dynamics. We use a simulation-based approach to assess how often errors in detection or classification occur in order to validate the use of temporal occupancy as a metric for inferring whether a species is a core or transient member of a community. We found that low detection increases error in the classification of core species, while high habitat heterogeneity and high detection increase error in classification of transient species. These findings confirm that temporal occupancy is a valid metric for inferring whether a species can maintain a self-sustaining population, but imperfect detection, low abundance, and highly heterogeneous landscapes may yield high misclassification rates.

Determinism and stochasticity in the spatial–temporal continuum of ecological communities: the case of tropical mountains

“…It is also prone to errors when it is made based on observational data sampled in highly heterogeneous landscapes at relatively fine temporal scales (i.e. as is the case of our data, see extended discussions in Snell Taylor et al 2018, 2020). As such, instead of simply proposing a conjecture in the discussion of how communities are structured by differences in turnover dynamics of these two types of species, we provide a demonstration based on a theoretical model (details in the Supporting information).…”

“…The first condition is that not all species found in a given community at a specific moment in time are in equilibrium with local habitat conditions. As such, local communities are composed of two different types of species: core and occasional (sensu Magurran and Henderson 2003, Snell Taylor et al 2018, 2020). Core species are those whose environmental requirements match with local habitat conditions and, consequently, can sustain viable local populations over time even in the absence of immigration (Coyle et al 2013).…”

Using temporal occupancy to predict avian species distributions

“…Nevertheless, the failure to account for imperfect detection does not impede our ability to compare SDM performance between presence–absence and temporal occupancy models, the primary goal of this manuscript. Furthermore, the use of temporal occupancy as an indicator of whether a species truly maintains a viable population at a given site despite imperfect detection has been validated with simulation models (Snell Taylor, Coyle, et al., 2020). High temporal occupancy accurately reflected sites with high suitability except in cases where the focal site was an unsuitable population sink surrounded by a landscape of more than 60% suitable habitat.…”