Comparison of Two Color-Marking Techniques For American Kestrels In South Texas

Abstract

We compared two color-marking techniques, celluloid color leg bands and colored dye on the feathers, for individual identification of American Kestrels (Falco sparverius). We trapped and color-marked 65 kestrels in October through December of 2014 and 2015. We searched for kestrels once a week with binoculars and a spotting scope and each time, recorded how kestrels were marked, either by bands, dye, or both. We confirmed that seven of the 195 color bands were lost during the study. The longest time that dye was still visible was 149 d after marking. We saw color bands from a maximum distance of 245 m and color dye from a maximum distance of 428 m. Of kestrels we were able to identify at least 10 times (n = 39) within the season that markings were applied, we saw only dye 17.3% of the time and only bands 19.4% of the time. We saw both markers (dye and at least one band) 63.3% of the time. Both methods can be used for successful identification of wintering kestrels, but a combination of the two techniques can increase the chance of seeing an identifiable mark. Color bands are long-term markers and allow identification of kestrels whose dye has faded or those that return in following years. Color dye makes it easier to identify kestrels that are difficult to approach, as well as those with territories extending away from accessible roadways.