Thursday, July 21, 2016

Perfect Perches, Part XII

King of the Boreal Forest                                              24 June 2016

The Black-throated Green Warbler is a beautiful representative of the boreal forest, most often requiring mature, tall conifers such as white spruce, black spruce, balsam fir, or white pine for nesting and foraging.  While they are mostly dependent upon the conifers for nesting, Black-throated Green Warblers are most abundant where deciduous trees such as quaking aspen, sugar maple, red maple, paper birch, and yellow birch outnumber the conifer component.  Perhaps this deciduous habitat provides the most consistently rich insect prey.  In some places, such as Sugar Camp Hill in the Brule River State Forest, this warbler is a common and successful breeding bird in a landscape strongly dominated by hardwoods and with surprisingly few conifers. For the most part, however, you should be expecting to hear its "zeee zee zee zoo zee" song in a classic mixed boreal forest with tall conifers, aspen and birch.

Like so many species of boreal birds, and like so many species of warblers, the Black-throated Green Warbler is a tropical migrant, departing for Mexico, Central America, the Caribbean and northern South America in September.  Many Black-throated Green Warblers make a complete migration over the open expanses of the Gulf of Mexico, and they are known to complete miniature migrations in pursuit of insect prey over their wintering grounds, sometimes moving laterally from the Pacific to the Atlantic and up and down mountain elevations.

In both boreal and tropical forests, Black-throated Green Warblers form close feeding associations with permanent resident species.  As a long-distance migrant, there is great efficiency in paying attention to the locals.  John Muir has provided an excellent model of thinking concerning boreal birds and their relationships with a large and continuous landscape in his famous quote, "When one tugs on a single thing in nature, he finds it is connected to the rest of the world."

This image was made using a Canon 7D, Canon EF 400mm 5.6 L lens, a Gitzo Basalt tripod, and an Induro ball head.