Above: Yellow-rumped warbler on wax myrtle.

Yellow-rumped warblers (also know as myrtle warblers) are not the only animals that eat wax myrtle fruit. I read somewhere that some 42 bird species consume the wax-coated seeds of the shrub. Besides the above mentioned warbler, I can only remember seeing a handful of species of bird partake, ruby-crowned kinglet, eastern phoebe, and a few more. Regardless of how many birds or other animals eat the wax myrtle fruit, the grand prize winner is the warbler.

The blue-gray fruit of wax myrtle is a staple for yellow-rumped warblers. They’re insectivorous birds at heart, but can switch to fruit when necessary, like in winter when few insects are about. This allows them to stay further north in winter than most of their warbler relatives which migrant to Central or South America or the Bahamian or Caribbean  islands.

By this time of year most of the fruit is gone, eaten by the birds. But there are two shrubs in the wetlands that for some reason still have plenty left to eat, and gray squirrels are having at it. For the past week, I’ve noticed a squirrel busily going through the shrubs, picking them clean.

Wax myrtle is native to the coastal plain. The shrubs here at the museum were originally landscaped in. But, through the action of birds the shrubs can quickly replant themselves, and they seem to do well in most growing situations.

Yellow-rumped warblers are named for the patch of yellow feathers on their rumps. This yellow patch of feathers is also the root of a nickname given the birds, “butter-butt.”

At one time, their common name was myrtle warbler because of their association with the plant, wax myrtle. About forty some years ago it was changed to yellow-rumped warbler due to another version of this bird which lives and breeds in the western part of North America. It, was formerly known as Audubon’s warbler. Because the two birds hybridize along an area in Canada where the two (myrtle and Audubon’s warbler) breeding ranges overlap, they were lumped into one species called yellow-rumped warbler. They were considered races of one species.

No matter what their official name is, I prefer to call them butter-butts.

If you want to see one of these birds, keep watch on a wax myrtle which has plenty of fruit on its branches, sooner or later, one’ll show up.