See all posts in the Birds of Carver County series
The northern yellow warbler, Setophaga aestiva, had a name change in 2025 when ornithologists wanted to separate the species seen in most of North America from the rusty-headed version found in the mangroves in Texas and Florida and in the Galapagos Islands. The Minnesota version migrates northward in late April and in May, then returns to Central and South America in September. They nest here and are often near wet and shrubby areas. You will not see them at seed feeders, but they will be munching on caterpillars and other insects throughout the summer. The Rapids Lake National Wildlife Refuge is a location where they can usually be seen along the riverside trail.
All-yellow undersides and continual movement are characteristics that help identify northern yellow warblers in May. They are five inches (12-13 cm) long with an eight-inch wingspan, weighing nine to 11 grams (.33 ounces), their pointed beak and behavior, they are classic “warblers.” Their olive backs, tails and wings contrast with their yellow underparts.
Once established in a territory, males sing a lot. One of their songs is said to resemble the mnemonic phrase “Sweet, sweet, I’m so sweet.” Other bird species might not be as kind as us, because the males aren’t really sweet – they sing loudly and are aggressive to trespassers.
You can identify males if you see rusty streaks on their chest. Females lack those streaks. They also have a yellow eye-ring. Both sexes lose some of their bright color as the months pass, so in September it’s more difficult to tell them apart. The pair is monogamous and may be together for more than one season, although, like most warblers, they only live a few years before they succumb to the hazards of migration, predation and even spider webs.
During nesting, they have an ongoing battle with cowbirds which destroy the warbler’s eggs and try to replace them with their own. The female incubates the eggs almost continually for about 11 days. The nestlings can leave the nest 8-10 days after hatching. They stay near their parents for the next two to three weeks. Around the nest, the males may not sing as much as earlier in the season.
This warbler is one of the earliest species to depart—in August and September. Wintering in places like Costa Rica, the northern yellow warbler helps growers defend their coffee crop from agricultural pests. During your next cup of coffee, why not make a toast to this beautiful yellow songbird that typifies summer birds in Carver County.
For more information:
- The Sibley Guide to Birds, David Allen Sibley
- Reader’s Digest Book of North American Birds
- Birds of Minnesota and Wisconsin, Janssen, Tessen, and Kennedy
- Breeding Birds of Minnesota, Pfannmuller, Niemi and Green
- The Audubon Society’s Encyclopedia of North American Birds, John K. Terres
- Birds of the World, Cornell Lab of Ornithology
- Online: All About Birds, Cornell Lab of Ornithology LINK
- Online: Minnesota Breeding Bird Atlas
