# Clarifying space use concepts in ecology: Range vs. occurrence distributions

## TL;DR

This paper clarifies the difference between range and occurrence distributions in animal movement studies to improve ecological and conservation research.

## Contribution

The paper distinguishes between range and occurrence distribution estimators and highlights their appropriate uses in ecology.

## Key findings

- Confusing range and occurrence distributions can lead to inaccurate home range estimates.
- Occurrence distribution estimators often produce smaller home ranges, especially with high-frequency tracking data.
- Range distribution estimators are better suited for quantifying home ranges, while occurrence estimators are useful for specific movement questions.

## Abstract

Quantifying animal movements is necessary for answering a wide array of research questions in ecology and conservation biology. Consequently, ecologists have made considerable efforts to identify the best way to estimate an animal's home range, and many methods of estimating home ranges have arisen over the past half a century. Most of these methods fall into two distinct categories of estimators that have only recently been described in statistical detail: those that measure range distributions (methods such as kernel density estimation that quantify the long‐run behavior of a movement process that features restricted space use) and those that measure occurrence distributions (methods such as Brownian bridge movement models and the Correlated Random Walk Library that quantify uncertainty in an animal movement path during a specific period of observation). In this paper, we use theory, simulations, and empirical analysis to demonstrate the importance of appropriately using these two categories of distributions and their estimators. Conflating range and occurrence distributions can have serious consequences for ecological inference and conservation practice. For example, in most situations, home ranges estimated using estimators of occurrence distributions are too small, and this problem is exacerbated by ongoing improvements in tracking technology that enable more frequent and more accurate data on animal movements. We encourage researchers to use estimators of range distributions to quantify home ranges and estimators of occurrence distributions to answer other questions in movement ecology, such as when and where an animal crossed a linear feature, visited a location of interest, or interacted with other animals.