March 7, 2019
The Ballad of the Butterbutt
Posted by: Rock Delliquanti
*photo above - Ryan Schain
The Yellow-rumped Warbler (Setophaga coronata) is a mid-sized warbler that overwinters here on Little St Simons Island. From October until May, these songbirds utilize the veritable buffet of insects, fruits, and seeds by gorging themselves in preparation for spring migration. You’ll know you’re looking at a Yellow-rumped Warbler when you see a muted black-and-white stripy songbird with yellow patches under the wing, on the top of the head, and above the tail on their rump (this earns them the loving nickname of “Butterbutt”). Most often you’ll find these handsome birds flitting among the shrubs and trees at Norm’s Pond, Myrtle Pond, and Goose Pond.
While we have other songbirds here on the island during the Winter months (Pine Warblers, Palm Warblers, and Black-and-white Warblers to name a few), the Yellow-rumped Warblers are particularly special because of their versatility in foraging. Not only do they glean insects on the wing, skim them off the water, and pick them out of spiderwebs, but they will readily switch to fruits and seeds in the fall and winter, and most notably, they can digest the waxy berries from our southern wax myrtle trees (Myrica cerifera). This lets these warblers overwinter much farther north than some of their kin who are acclimated to insects or fruits and seeds which are only available further south during the cold-weather months.
Interestingly, the Yellow-rumped Warblers along the Atlantic Coast are a part of the Myrtle subspecies (Setophaga coronata coronata), differentiated from their West Coast (S. c. auduboni), Guatemalan (S. c. goldmani), and Mexican (S. c. nigrifrons) cousins by their white throat and black cheek. These subspecies are up for consideration to be split into separate species likely named: Myrtle Warbler, Audubon’s Warbler, Goldman’s Warbler, and potentially Black-fronted Warbler respectively. Genetic research has been showing that there are distinctions between some of these subspecies, and even though hybridization can occur, there may be enough evidence to designate distinct species.