Bay-Breasted Warbler

Setophaga castanea
Range Map

We know that Bay-Breasted Warblers love to prey on Spruce Budworms (Choristoneura fumiferana). We also know that populations of these warblers fluctuate from year to year, depending on the number of budworms available. When budworm populations explode, as they do every 30 to 40 years, they can decimate millions of acres of spruce and Balsom Fir trees. So birds like these and other warblers play an important role in a healthy forest.

Bay-Breasted Warblers enjoy similar summer habitats and diets as Cape May, Blackburnian, and Blackpoll Warblers. One strategy employed by these birds is how they locate their nests to minimize conflicts. Blackpoll Warblers nest very low (about 5 feet) in the tree, and Bay-Breasted higher (about 16 feet), while Cape May and Blackburnian Warblers nest at 40 to 80 feet.

During summer, we find these warblers in Canada’s lower elevation forests from southern Northwest Territory to the Maritime Provinces and northern New England (USA). In winter, they retreat to the West Indies, the Caribbean, Central America and northern South America.

I’ve only met this species once. It was during spring migration when I was on South Padre Island. It was a female (shown below). One day I hope to meet the male bird.

Modern science does not recognise any subspecies of Bay-Breasted Warblers (i.e. they are monotypic).

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