See all posts in the Birds of Carver County series
The scientific name for the bay-breasted warbler is Setophaga (sometimes Dendroica) castanea. Castanea is Latin for the chestnut or bay coloration associated with the species. In the summer, they nest in Lake and St. Louis counties and in Canada. When the whims of nature infest the spruce forests up north with budworms, bay-breasted warblers will rise to the occasion and build up their population and feed during the long days of summer.
However, in Carver County, like most of the warbler family, the bay-breasted will pass through our woodlands quickly in May and return a little slower in August and September. If we’re lucky, those brief weeks provide us with the opportunity to notice classic warbler characteristics—males look different from females, their fall version quite different than the spring look, and the young male will be similar to the adult female. Adding to the identification challenge, these active, hungry birds don’t have a lot of time to sightsee, so their feeding is continual. The leaves provide them cover and our eyes can never quite keep up with their movements.
All those conditions add to the birder’s enjoyment when one or more of these birds can be identified. On his way north, the male shows a black facemask, topped with a dark brown cap and a chestnut throat and upper chest. Two bright white wing bars are separated by a contrasting dark bar. Females have gray faces but have the same wing bars and white bellies of their potential mates. They also show some brown near their shoulders and flanks. In the fall, the males are less colorful, the females lose some color contrast, and differentiating bay-breasted from other migrating warblers becomes harder. Chestnut-sided, blackpoll and pine warblers may deceive one trying to catch a glimpse of a bay-breasted.
The species migrates at night, so starting in mid-May and mid-August, pay attention to clear weather and winds towards the direction of migration. Look for active feeding on insects in the mornings and late afternoons. The song of the male bay-breasted is hard to hear, with a low volume and very high pitch. It is no surprise that the sound doesn’t carry far and is difficult to localize (unless you are another bird).
Interesting facts
- When spending the winter in Panama and Colombia, bay-breasted warblers change their diet to fruit during the dry season of Jan to April.
- The bay-breasted is one of three spruce budworm specialists that include the Cape May and Tennessee warblers.
In spring, the male bay-breasted warbler stands out. A second look may reward you with a lasting image that could take months or years to be repeated. Keeping our eyes in the trees during May and September relies on those brief successful moments and fuels our optimism in the transition seasons.
For more information:
- The Sibley Guide to Birds, David Allen Sibley
- The Warbler Guide, Stephenson and Whittle
- Reader’s Digest Book of North American Birds
- Birds of Minnesota, Robert B. Janssen
- Breeding Birds of Minnesota, Pfannmuller, Niemi and Green
- The Audubon Society’s Encyclopedia of North American Birds, John K. Terres
- Birds of the World, Cornell Lab of Ornithology
- Online: All About Birds, Cornell Lab of Ornithology LINK
- Online: Minnesota Breeding Bird Atlas
