Cool Critters: Sweet song, bright feathers – why the American yellow warbler is everywhere and nowhere

The American yellow warbler is known for its sunny-yellow plumage and sweet song.

But as any birder will tell you, they’re also fidgety. Trying to get a clear view of them is like seeing flashes of sunlight dance between leaves.

“They’re small and constantly moving, so they test your patience,” said Terri Arronge of Mead, who spent a recent morning near Deadman Creek trying to get a clear photograph of a yellow warbler amid a thicket of cottonwood trees. The instant she’d aim her camera, the bird would vanish from the frame, she said.

“I kept seeing little circles of yellow hopping around the leafy treetops,” Arronge recalled. “I remember thinking, if only it would sit still!”

Finally, the warbler did sit, immediately after it snatched a green caterpillar. With a full view of the bird, Arronge snapped away.

“Oh, gosh. It took patience, but also luck,” she said of the image she captured that’s featured in today’s column.

Slightly bigger than a goldfinch and weighing less than a sugar packet, the American yellow warbler adds vibrant color and sound to the Inland Northwest after it returns from its wintering grounds in Central and South America. Often, the bird’s melodious series of whistles will alert you that one is nearby, as did the warbler that tipped off Arronge.

If you hear a pattern that sounds like, “sweet-sweet-sweet; I’m so sweet,” look upward toward the trees.

“Males sing their sweet, whistled songs from high perches,” mostly near the tops of leafy trees such as cottonwoods, alders and willows, according to the Cornell Lab of Ornithology.

Also, the birds’ frenetic movements are part of their hunting strategy, Cornell states on its website. “They forage restlessly, with quick hops along small branches and twigs to glean caterpillars and other insects.”

That diet is why you don’t see yellow warblers at bird feeders. What’s more, you won’t see yellow warblers raising babies of the brown-headed cowbird.

The brown-headed cowbird is notorious for laying eggs in the nests of more than 200 bird species and basically tricking those birds into raising the cowbird’s babies. But the yellow warbler deploys a unique strategy to keep that from happening. It issues a distinct alarm call to warn other warblers that an on-the-prowl cowbird is nearby. Instead of mobbing the would-be intruder, the female warblers zip back to their nests and sit firmly to prevent the cowbird from laying eggs there.

The yellow warbler’s staccato warning call is only used against the brown-headed cowbird, making it unique among bird species, according to the National Audubon Society.

Its “Watch out for the cowbird!” alert is so effective that at least one other bird species benefits from hearing it. In a study published in the May 2020 journal Communications Biology, researchers found that red-winged blackbirds respond to the warbler’s call by returning to their nests to stand guard.

As challenging as American yellow warblers are for humans to view and photograph, there’s good reason why these tiny, colorful gems are all atwitter. Enjoy their sweet song and flashes of yellow this summer. And keep in mind that their fall migration begins earlier than most birds, with many departing southbound mid-August.