Evaluation methods for gender determination of lesser Kestrel nestlings ; Evaluación de métodos para la determinación del sexo en pollos de Falco naumannis

[ENG]Thc traditional method of determining gender of Lesser Kestrel (Falco naumanni) nestlings by visual assessment was tested for accuracy by using data from birds banded as nestlings and recaptured as adults. Concordance between gender assignment by different observers, and between visual and molecular gender determination was also evaluated. We tcsted whether color measurement of rssmps and tails could improve gender determination. Based on recaptured kestrels, gender determination by eye had a 9.7% error, and was significantly greater for males than for females. Observers mostly relied on rump and tail color to assign gender to nestlings. Assessment of head, shoulders, tail, and rump patterns did not provide additional information that could improve gender determination in nestlings at the time of banding. Gender assignment based on color measurement on digital photos of rumps and tails did not improve determination by eye, but color measurement from a scanned rump feather approached 100% accuracy. We provide a discriminant function equation based on red, green, and blue brightness values (RGB) of a scanned rump feather and propose this as an efficient and effective method for gender determination in Lesser Kestrel nestlings ; [ES] Evaluamos Ia forma tradicional de determinar visualmente el sexo de los pollos de Falco naumanni mediante las reeapturas de individuos adultos anillados, cuyo sexo habia sido determiuado en Ia etapa de pollos. Se ealeuló la coneordancia en la determinaciôn del sexo entre diferentes obser­ vadores, asi eomo entre la determinaeión del sexo de modo molecular y visual. Además, se investigó si medidas del color de la cola y Ia rabadilla determinadas a partir de fotografias digitales o de plumas de la rabadilla escaneadas aumentaban el poreentaje de acierto en la determinacion del sexo de los pollos. El porcentaje de error en la determinación visual del sexo fue de 9.7%, y foe significativamente mayor en el caso de los machos. Los observadores se basaron mayormente en el color de Ia ...