### Abstract

Ring re-encounter data, in particular ring recoveries, have made a large contribution to our understanding of bird movements. However, almost every study based on ring re-encounter data has struggled with the bias caused by unequal observer distribution. Re-encounter probabilities are strongly heterogeneous in space and over time. If this heterogeneity can be measured or at least controlled for, the enormous number of ring re-encounter data collected can be used effectively to answer many questions. Here, we review four different approaches to account for heterogeneity in observer distribution in spatial analyses of ring re-encounter data. The first approach is to measure re-encounter probability directly. We suggest that variation in ring re-encounter probability could be estimated by combining data whose re-encounter probabilities are close to one (radio or satellite telemetry) with data whose re-encounter probabilities are low (ring re-encounter data). The second approach is to measure the spatial variation in re-encounter probabilities using environmental covariates. It should be possible to identify powerful predictors for ring re-encounter probabilities. A third approach consists of the comparison of the actual observations with all possible observations using randomization techniques. We encourage combining such randomisations with ring re-encounter models that we discuss as a fourth approach. Ring re-encounter models are based on the comparison of groups with equal re-encounter probabilities. Together these four approaches could improve our understanding of bird movements considerably. We discuss their advantages and limitations and give directions for future research.

Original language | English |
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Pages (from-to) | 8-17 |

Journal | Journal of Avian Biology |

Volume | 41 |

Issue number | 1 |

DOIs | |

Publication status | Published - 2010 |

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## Cite this

Korner-Nievergelt, F., Sauter, A., Atkinson, P. W., Guelat, J., Kania, W., Kery, M., Koppen, U., Robinson, R. A., Schaub, M., Thorup, K., Van der Jeugd, H. P., & Van Noordwijk, A. J. (2010). Improving the analysis of movement data from marked individuals through explicit estimation of observer heterogeneity.

*Journal of Avian Biology*,*41*(1), 8-17. https://doi.org/10.1111/j.1600-048X.2009.04907.x