Measuring neck collar loss of Pink-footed Geese

Summary

Ringing with plastic neck collars have become a widely used marking technique in waterbird ecology. Neck collars allow researchers to track the life history of individual birds (by continuous re-sightings of marked individuals). Tracking individuals is useful to studies of migration, survival, harvest, behaviour and population size. While it is broadly acknowledged that collar loss can substantially bias the results of these studies by introducing false negatives in the encounter history of individual birds, independent data to estimate retention rate of neck collars are very scarce. As a consequence, neck collar loss is often assumed to be negligible. However, to ensure confidence regarding the outcome of population studies using re-sightings of marked birds, quantitative estimates of collar loss are very important. Based on 23 years of neck collar recovery data from the Svalbard breeding population of Pink-footed Geese, it is estimated that there is an overall average annual loss rate of 3.2%. However, neck collar loss was similar between males and females, and did not (based on currently available data) differ significantly between two types of collars used.

The study is described in an article published in BTO Bird Study and is available on-line.

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