Relationship between resource selection, distribution, and abundance: a test with implications to theory and conservation

Abstract

Much of applied and theoretical ecology is concerned with the interactions of habitat quality, animal distribution, and population abundance. We tested a technique that uses resource selection functions (RSF) to scale animal density to the relative probability of selecting a patch of habitat. Following an accurate survey of a reference block, the habitat‐based density estimator can be used to predict population abundance for other areas with no or unreliable survey data. We parameterized and tested the technique using multiple years of radiotelemetry locations and survey data collected for woodland caribou across four landscape‐level survey blocks. The habitat‐based density estimator performed poorly. Predictions were no better than those of a simple area estimator and in some cases deviated from the observed by a factor of 10. We developed a simulation model to investigate factors that might influence prediction success. We experimentally manipulated population density, caribou distribution, ability of animals to track carrying capacity, and precision of the estimation equation. Our simulations suggested that interactions between population density, the size of the reference block, and the pattern of distribution can lead to large discrepancies between observed and predicted population numbers. Over‐ or undermatching patch carrying capacity and precision of the estimator can influence predictions, but the effect is much less extreme. Although there is some empirical and theoretical evidence to support a relationship between animal abundance and resource selection, our study suggests that a number of factors can seriously confound these relationships. Habitat‐based density estimators might be effective where a stable, isolated population at equilibrium is used to generate predictions for areas with similar population parameters and ecological conditions.

A spatial scale assessment of habitat effects on arthropod communities of an oceanic island

“…Their abundance in pastures is the sole explanatory factor for the almost inexistence of significant correlations when habitats are compared by their absolute abundance of endemics. Notably, population density is generally difficult to predict by using habitat variables (Johnson and Seip, 2008). In this study, correlations between endemic species abundance and habitat area were always low both at local and regional scales.…”

Using habitat suitability models to sample rare species in high-altitude ecosystems: a case study with Tibetan argali

“…An important caveat here is that habitat selection does not necessarily reflect quality of habitat (van Horne 1983;Johnson and Seip 2008). It describes the current species distribution or the realised niche of the species, which results from competition with livestock, disturbance, predation and several other biotic and abiotic factors.…”

Selection for forage and avoidance of risk by woodland caribou (Rangifer tarandus caribou) at coarse and local scales

“…Habitat selection studies have been used to define ranges (Johnson and Seip 2008) and identify critical habitats (Nielsen et al 2006) pursuant to conservation or management goals. Predicting these changes in habitat selection is key to understanding observed shifts in habitat needs between pristine and disturbed landscapes (Osko et al 2004).…”