A relatively large number of North American hybrid hummingbirds have been described (Banks and Johnson 1961, Short and Phillips 1966, Mayr and Short 1970), representing at least 12 hybrid combinations, mostly intergeneric (Wells et al. 1978). Nearly all known hybrids have been adult males, and the evidence for their presumed hybrid origin has been based primarily upon the external characters of specimens.
In late December 1977 a female Blue-throated hummingbird (Lampornis clemenciae) was discovered visiting a feeder near Three Rivers, Tulare County, California. This bird, the first of the species recorded in California (Luther et al. 1979), subsequently nested twice in the vicinity. Because of the apparent absence of a male Blue-throated Hummingbird, as well as certain characteristics of the young, we believe that these nesting attempts involved hybridization. In the following account the nesting attempts and the resultant offspring are described, and the possible identity of the male parent is discussed. We are unaware of a previous report of a hummingbird hybridization discovered during the nesting stage.