Journal article 1143 views
Effects of sampling regime on the mean and variance of home range size estimates
Journal of Animal Ecology, Volume: 75, Issue: 6, Pages: 1393 - 1405
Swansea University Authors: Novella Franconi , Luca Borger
Full text not available from this repository: check for access using links below.
DOI (Published version): 10.1111/j.1365-2656.2006.01164.x
1. Although 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 concer...
|Published in:||Journal of Animal Ecology|
No Tags, Be the first to tag this record!
1. Although 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.2. We propose a new procedure, based on a variance components analysis using generalized mixed effects models to examine how estimates vary with sampling regime.3. To 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.4. Variation 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%.5. Using 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.6. The 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.7. We 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.
animal movement; home range; radio-tracking;
Faculty of Science and Engineering