Setting harness sizes and other marking techniques for a falcon with strong sexual dimorphism
2001
Kenward, Robert E. | Pfeffer, Ralf H. | Al-Bowardi, Mohamed A. | Fox, Nicholas C. | Riddle, Kenton E. | Bragin, Evgeny A. | Levin, Anatoli | Walls, Sean S. | Hodder, K. H. (Kathy H.)
Backpack radio-tags can be used to monitor survival of raptors for several years after fledging, but may reduce survival if a poor fit results from subjective judgments. We present an attachment method that can use bird measurements to predict harness sizes. Relationships between body mass of Saker Falcons and harness size predicted the size for smaller falcon species. Harnesses were fitted when birds had reached full size in the nest, which required age estimation at a previous visit to predict a fledging date. Equations based on wing length provided objective aging of nestlings. A pump-pressured water gun aided capture of young falcons and toggle-loops restrained the feet during marking. Saker Falcons with radio-tags and others marked only with leg bands and implanted transponders had the same recapture rate (7%) in autumn, indicating similar survival. This retrap rate should be adequate to estimate harvest rates and population sizes for Saker Falcons.
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