Estimating the movements of terrestrial animal populations using broad-scale occurrence data

Abstract

As human and automated sensor networks collect increasingly massive volumes of animal observations, new opportunities have arisen to use these data to infer or track species movements. Sources of broad scale occurrence datasets include crowdsourced databases, such as eBird and iNaturalist, weather surveillance radars, and passive automated sensors including acoustic monitoring units and camera trap networks. Such data resources represent static observations, typically at the species level, at a given location. Nonetheless, by combining multiple observations across many locations and times it is possible to infer spatially continuous population-level movements. Population-level movement characterizes the aggregated movement of individuals comprising a population, such as range contractions, expansions, climate tracking, or migration, that can result from physical, behavioral, or demographic processes. A desire to model population movements from such forms of occurrence data has led to an evolving field that has created new analytical and statistical approaches that can account for spatial and temporal sampling bias in the observations. The insights generated from the growth of population-level movement research can complement the insights from focal tracking studies, and elucidate mechanisms driving changes in population distributions at potentially larger spatial and temporal scales. This review will summarize current broad-scale occurrence datasets, discuss the latest approaches for utilizing them in population-level movement analyses, and highlight studies where such analyses have provided ecological insights. We outline the conceptual approaches and common methodological steps to infer movements from spatially distributed occurrence data that currently exist for terrestrial animals, though similar approaches may be applicable to plants, freshwater, or marine organisms.

Effects of temperature on monarch caterpillar pigment variation in nature

“…Our characterisation of monarch caterpillar pigment variation in nature was made possible by the thousands of photos uploaded to iNaturalist by scientists and the general public. This user‐friendly and accessible biodiversity repository is quickly becoming an invaluable tool for the study of conservation (Light et al, 2021; Mesaglio et al, 2021), movement ecology (Supp et al, 2021), invasive species (Young et al, 2021), behavioural ecology (Clark et al, 2021), phenology (Jaskuła et al, 2021) and science outreach (Niemiller et al, 2021). Here we add to this list of applications by quantifying insect pigment variation in nature.…”

BirdFlow: Learning Seasonal Bird Movements from eBird Data

“…Previous studies have approached modeling movement from observational data by first extensively cleaning the data to correct for variability from the observation process, and then investigating specific quantities of interest like centroid movement or estimated movement speed (Supp et al, 2021). Other promising approaches include deterministic models based on the concept of global energy efficiency, in which simulated birds are distributed to optimize both resource acquisition and energy expenditure (Somveille et al, 2021).…”

“…Previous studies have approached modeling movement from observational data by first extensively cleaning the data to correct for variability from the observation process, and then investigating specific quantities of interest like centroid movement or estimated movement speed (Supp et al, 2021). Some recent work has used relative abundance models from eBird Status & Trends to study migratory connectivity.…”

BirdFlow: Learning seasonal bird movements from eBird data

“…Previous studies have approached modelling movement from observational data by first extensively cleaning the data to correct for variability from the observation process, and then investigating specific quantities of interest like centroid movement or estimated movement speed (Supp et al, 2021). Some recent work has used relative abundance models from eBird Status & Trends to study migratory connectivity.…”