This temporally and spatially extralimital juvenile male Pine Warbler was an unexpected find at Ovid Woods in Sedgwick County, northeastern Colorado (USA) on 4 July 2010. I observed this bird together with Cole Wild.
The bird was a very drab individual, which made identifying the bird somewhat challenging. It appears to be a juvenile male by plumage (fresh, juvenal plumage with extensive white on inner webs of outer rectrices indicating male). Male sex was confirmed by its delivery of a feeble, weak song in addition to chip notes. The song was a rapid succession of notes, about 12 notes, given in a slow choppy staccato of uneven pitches, rather than a rapid trill of evenly pitched notes typical of the adult male.
What is a hatch-year Pine Warbler doing in Colorado in early summer? The closest breeding populations are located 700+ miles northeast of Colorado in Wisconsin and 800+ miles southeast in east Texas. A few individuals attempt to winter each year in Colorado, so it may be there there are a small number of extralimital nests somewhere in or near Colorado. However, I doubt that juveniles from any nearby nests or from northern nests in Wisconsin would be ready for southward migration or even independence from family groups at such an early date. Texas breeding however may start much earlier in the year. Several days prior to this sighting, winds from tropical storm Alex reached Colorado, so a solution to this puzzle is that this bird is a product of an early nest in east Texas and aleady engaged in post-breeding dispersal aided by strong winds!
The second row of photos were taken in deep shade and have been edited to lighten and brighten the images. Note that the "correction" software used in the editing exaggerated the degree of yellow in the breast and olive on the upperparts, but these features more closely resemble adult coloration!
