It's raining this morning, but last evening there was a mixed-flock of songbirds that included Yellow-rumped Warblers, Golden-crowned Kinglets, a very early Northern Parula, and my first Ruby-crowned Kinglet of spring. The birds were actively feeding on what appeared to be a hatching of midge flies. Speaking of kinglets, did you know that despite their current taxonomic placement, Ruby-crowned and Golden-crowned kinglets are not particularly closely related within Regulidae?
The 2 North American kinglets (Golden-crowned and Ruby-crowned) are probably not closely related sister taxa. They differ in scutellation pattern of toe 4, a pattern that Golden-crowned Kinglet shares with the Eurasian species (Clark 1974, pers. comm.). Electrophoretic studies (Ingold et al. 1988) produced a substantial genetic difference between Golden-crowned and Ruby-crowned kinglets, a distance typical of different passerine genera … a comprehensive study of all species of Regulus, both biochemical and behavioral, is needed to define correct affinities.
~ The Birds of North America
Ruby-crowned Kinglet © 2011 Mike McDowell