Evidence of Hybridization between Red-Bellied and Golden-Fronted Woodpeckers

Abstract

Golden-fronted Woodpeckers (Melanerpes aurifrons) and Red-bellied Woodpeckers (M. carolinus) are sympatric from southwestern Oklahoma to eastern Texas. Earlier studies found no evidence of hybridization (Selander and Giller 1963). However, in the recent past the area of range overlap between these two species has increased, thereby increasing the opportunity for hybridization. I investigated the possibility of hybridization by analyzing morphological and electrophoretic characteristics. Twenty-five (15.8%) individuals with intermediate morphologies were collected within the area of overlap and were identified as putative hybrids. Electrophoretic analysis of 12 liver and muscle proteins revealed a close genic affinity between the two species. Individual genic complements within the zone of overlap indicate that some individuals are intermediate. The intermediate morphology and mixed genic composition of some individuals within the zone of overlap supports the conclusion that Red-bellied and Golden-fronted woodpeckers hybridize.