At this time of year, the arb serves as an important stopover point for many migrant bird species. Check them out soon, before they continue northward, or are obscured by spring foliage! Among the species recently reported in the arb are Yellow-rumped Warblers, Orange-crowned Warblers, American Redstarts and Blue-gray Gnatcatchers. Most of these small, colorful birds are neotropical migrants which have spent the winter in Central or Southern America, and are currently en route to their nesting grounds in Canadian boreal forests.
In addition to these temporary visitors, the arb is also full of recently returned birds here to stay for the summer. Baltimore orioles can be spotted in pairs, beginning the process of constructing their distinctive, hanging nests. Male Red-winged Blackbirds are staking claim to pieces of marsh and shore-line, hoping to attract females with their territory and song. Eastern Bluebirds have colonized many of the bird boxes established in the arb. And now for a piece of bird trivia: Bluebirds (and, for that matter, all birds that appear blue in color) don’t actually have any blue pigments in their feathers. The blue that we perceive when looking at these birds is actually the result of structural color, or the physical alteration of light achieved by certain feather structures. If you looked at a backlit Bluebird feather, it wouldn’t appear blue at all, instead it would be a dull brown.
Just as a reminder, this Saturday is Carleton’s annual arboretum bird count, and everyone is welcome to participate! Meet at the tennis courts parking lot in the lower arb at 6 am with your binoculars and field guide, if you have them. Email arb director Nancy Braker (nbraker) with any questions.