If you’re very very old, you may remember a toothpaste jingle that began with “You’ll wonder where the yellow went, when you brush your teeth with ______.” This little bird is easy to identify when it’s summertime. The males have bright yellow patches on their crowns throats, breasts, rumps — you can hardly miss them. The females, like most birds, restrain themselves and go for the conservative look. Still, they advertise who they are with a telltale bright yellow patch on their rumps, earning the species the birder nickname “butterbutt.” Then comes winter. They turn vanilla, and the novice birder, such as myself, seeing no yellow, flounders for an identification. I’m again indebted to Jack Haynes for saving me from (another!) bad bird ID. There’s probably still a bit of a yellow patch on this female’s rump, but it’s covered by her flight feathers as she sits, and we can’t see it.
These warblers typically travel in flocks, the sources say. Not here. Every time I’ve seen one in the park (with its yellow on), it’s been a solo or perhaps a pair. Apparently the large group winter travel option is more popular on the east coast.
I saw this one on the north side in the fennel forest. I didn’t see it eat anything, but it had choices, and it’s not picky. This species, according to the Cornell bird lab, “are perhaps the most versatile foragers of all warblers. They’re the warbler you’re most likely to see fluttering out from a tree to catch a flying insect, and they’re also quick to switch over to eating berries in fall. Other places Yellow-rumped Warblers have been spotted foraging include picking at insects on washed-up seaweed at the beach, skimming insects from the surface of rivers and the ocean, picking them out of spiderwebs, and grabbing them off piles of manure.” They will also eat a great variety of seeds, and sometimes come to feeders.