Effects of sampling regime on the mean and variance of home range size estimates
Article first published online: 5 SEP 2006
Journal of Animal Ecology
Volume 75, Issue 6, pages 1393–1405, November 2006
How to Cite
BÖRGER, L., FRANCONI, N., DE MICHELE, G., GANTZ, A., MESCHI, F., MANICA, A., LOVARI, S. and COULSON, T. (2006), Effects of sampling regime on the mean and variance of home range size estimates. Journal of Animal Ecology, 75: 1393–1405. doi: 10.1111/j.1365-2656.2006.01164.x
- Issue published online: 26 SEP 2006
- Article first published online: 5 SEP 2006
- Received 24 March 2006; accepted 3 August 2006
- animal movements;
- site fidelity;
- space use;
- 1Although the home range is a fundamental ecological concept, there is considerable debate over how it is best measured. There is a substantial literature concerning the precision and accuracy of all commonly used home range estimation methods; however, there has been considerably less work concerning how estimates vary with sampling regime, and how this affects statistical inferences.
- 2We propose a new procedure, based on a variance components analysis using generalized mixed effects models to examine how estimates vary with sampling regime.
- 3To demonstrate the method we analyse data from one study of 32 individually marked roe deer and another study of 21 individually marked kestrels. We subsampled these data to simulate increasingly less intense sampling regimes, and compared the performance of two kernel density estimation (KDE) methods, of the minimum convex polygon (MCP) and of the bivariate ellipse methods.
- 4Variation between individuals and study areas contributed most to the total variance in home range size. Contrary to recent concerns over reliability, both KDE methods were remarkably efficient, robust and unbiased: 10 fixes per month, if collected over a standardized number of days, were sufficient for accurate estimates of home range size. However, the commonly used 95% isopleth should be avoided; we recommend using isopleths between 90 and 50%.
- 5Using the same number of fixes does not guarantee unbiased home range estimates: statistical inferences differ with the number of days sampled, even if using KDE methods.
- 6The MCP method was highly inefficient and results were subject to considerable and unpredictable biases. The bivariate ellipse was not the most reliable method at low sample sizes.
- 7We conclude that effort should be directed at marking more individuals monitored over long periods at the expense of the sampling rate per individual. Statistical results are reliable only if the whole sampling regime is standardized. We derive practical guidelines for field studies and data analysis.