Our bread and butter(...butts!)

See the "butter"?

We all know Yellow-rumped Warblers at CFMS. They’re our most common capture, especially in the fall. Myrtles, MYWAs, Butterbutts—they’re the bread and butter(butt) of this station. We, as birders, tend to get a little bored of our most abundant birds... but while they are commonplace, they’re far from boring!

The Yellow-rumped Warblers (Setophaga coronata) here are the subspecies known as Myrtle Warbler (S. c. coronata), with white throats and white eyebrows. While in Alaska, they are mostly insectivorous (and are pretty acrobatic, sallying like flycatchers), but on their wintering grounds they eat berries and fruits, an unusual dietary choice for warblers. In fact, they got their name from their habit of eating the wax-myrtle berry (Myrica sp.). Imagine a gut biome that can handle all those food items! This is what allows them to winter further north than most other warblers. In the winter, Myrtles can be found in the southeastern U.S.—but also as far south as Central America and the Caribbean. Unfortunately, we don’t know exactly where our Creamer’s Field Myrtles go, but hopefully one of our many banded birds will be recaptured on their wintering grounds or migration stopovers soon.

This year, we’ve been catching tons of hatch-year Myrtles, meaning lots of Myrtle moms were busy building nests (they do it without the help of a male) and feeding chicks this summer. (The males DO help with that part.) Myrtles build cup nests, usually in a conifer, delicately lined with hair (sometimes from moose!) and feathers. As fall progresses, the chicks are losing their fuzzy baby feathers and the adults have lost their bright blue-and-black summer feathers, but their yellow patches are still highlighter-bright. Hope everyone can get out and catch a glimpse of a few more Myrtle butts this year—come February, we’ll surely be missing our buttery companions.

Banding got off to a late start today due to weather, but with only a few nets open, we still managed to catch a good number of birds—including our first of the year American Tree Sparrows.

~Laura