2 SONG POPULATIONS OF THE NORTHERN PARULA

Two distinctly different Type A songs characterize eastern and western populations within the breeding range of the Northern Parula (Parula americana). These two song variants differ mainly in the last note, but also have other significantly different frequency and temporal characters. The eastern-style singers terminate their song with two glissando-figures forming an inverted "V" on a sonagram. The western Type A song ends with a less intense buzzy note or vibrato-figure with an up slur. The song length of eastern birds averages 0.12 s shorter than western singers. Other significant differences include trill duration, trill rate, period between the first two syllables and the maximum frequencies of the first and last syllables. The two song populations are nearly allopatric, overlapping in southwestern Alabama and eastern Kentucky, where the two song forms can be heard in adjacent areas but where no intermediate songs are found. Morphological differences coupled with the differences in the Type A song suggest that the two populations are recognizable and may be in the early stages of allopatric divergence. I suggest that the eastern populations be recognized as P. americana americana and the western populations as P. americana ludoviciana.