Winter Warblers

Yellow-rumped Warblers (affectionately called “butter butts” by birders) winter further north than any other North American warbler. In summer, Yellow-rumped Warblers primarily eat insects, but switch over to berries in winter. They are one of very few species able to digest the waxy berries of plants such as the northern bayberry and wax myrtle, and their range coincides closely with the range of those plants. Northern bayberry (Myrica pensylvanica) shrubs are plentiful on Caven Point, at the southern tip of Liberty State Park in Jersey City, NJ, and many Yellow-rumped Warblers spend the winter in the park. Though not nearly as colorful as they are in their spring plumage, in winter they still sport yellow patches by their wings and of course those bright yellow rumps.

There are two subspecies of “butter butts” that live in the United States that until 1983 were considered to be distinct species: the Myrtle Warbler in the southeast and the Audubon’s Warbler of the west. The Myrtle Warbler was so named because of its relationship with the wax myrtle (Myrica cerifera), a close relative of the northern bayberry that grows primarily in the south.