MacGillivray's Warbler

On my stroll through South Platte Park this morning, I was fortunate to encounter a MacGillivray's warbler.  Not easily observed, this migrant favors riparian thickets on its way from Mexico and Central America to breeding grounds in the Western Mountains and Pacific Northwest.  Indeed, I found this morning's visitor in shrubs along the South Platte River and would have missed him altogether if I hadn't noticed movement of the foliage.

MacGillivray's warblers also nest in streamside thickets or dense understory, favoring new growth woodlands; here in Colorado, they are best found between elevations of 8500 and 10,000 feet during the summer months.  Like most warblers, they are insectivores, gleaning prey from the vegetation or directly from the ground.

Once considered to be a subspecies of the mourning warbler, which breeds in Canada and migrates through the central and eastern U.S., the birds are now classified as distinct species.  Regardless of his classification, today's visitor is likely to be one of the final spring migrants to pass through the Front Range urban corridor this year.