Warblers belong to one of the most common and abundant avian groups, yet they're among the least easily observable wild birds, during the peak of Minnesota's short growing seasons after full leaf-out has occurred.
Some species we tend to see much more often than others, such as the American redstart and yellow-rumped warbler.
Others we strive to see just once, like perhaps the golden-winged warbler or blackburnian warbler.
Still, there are many more species of warblers that only pass through our state during spring and fall migrations - some not at all. And there are warbler species that we rarely see but mostly only hear; and more species yet that are tree-top or thick understory dwellers that are genuine hiding Houdini's.
Thankfully, not all warblers are wood warblers or are otherwise warblers that spend most of their lives in forests and are thus difficult to observe.
Some, like the yellow warbler and common yellowthroat, are denizens of more open landscapes, especially transition zones where upland grassy-shrubby habitat meets wetlands and waterways. It's within these habitats that these two beautiful species of warblers can be found.
It's hard to misidentify the yellow warbler and common yellowthroat. Dissimilar to each other, let alone other warblers, no other warbler is colored nearly all yellow as is the yellow warbler, and no other warbler sports as bold a black mask across it face as does the common yellowthroat (only male common yellowthroats are completely masked).
I became intimately familiar with these two delightful species of warblers during my summers studying bird diversity throughout the Prairie Pothole Region of east-central North Dakota in the late 1990s.
Yellow warblers were abundant in the shrubby uplands adjacent to my study wetlands, whereas common yellowthroats were especially widespread closest to wetlands, often flitting about within willows, cattails, and sedges.
The songs of singing male yellow warblers and common yellowthroats are two of the most easily recognizable springtime birdsongs. Frequently sung by each species, both songs are distinctive and memorable. In fact each birds' song can be put to memory by reciting two mnemonics-the yellow warbler's "sweet, sweet, sweet, I'm-so-sweet" song, and the common yellowthroat's "witchety-witchety-witchety" song.
A female yellow warbler builds her nest in the vertical fork of shrubs and small trees. Nests are constructed of fine grasses and plant material, deer hair, and delicate feathers lining the inside cup.
She builds her nest in about four days, lays eggs, and incubates her eggs for around 10 to 14 days. Nestlings fledge fairly quickly, sometimes in as little time as nine days, but usually closer to two weeks.
Brown-headed cowbirds are known to target yellow warbler nests to lay their own eggs. Called brood parasitism, the nesting strategy of cowbirds is interesting and unique nonetheless. Noteworthy of female yellow warblers, however, is their counter strategy. She will often rebuild her nest on top of the cowbird eggs, including her own eggs, and start the process of laying and incubating new eggs.
Male common yellowthroats remind me of raccoons. Not only do the two species share a similar trait - the black mask across the eyes and face - but each also share an endearing natural inquisitiveness.
I've learned, for example, that it's quite easy to coax male common yellowthroats (and many other birds for that matter) to within mere feet by simply performing the well-known birder trick of producing "pishing" sounds.
Female common yellowthroats build their nests in marshy areas on or very near the ground within grasses, sedges, cattails, and other wetland associated vegetation.
Sometimes she constructs her grassy nest with a roof over it, much like the nest of a close warbler relative, the ovenbird. In all, from egg laying to her chicks fledging, nesting takes a little less than a month. And as is the case with many species of songbirds, a second brood is often raised, too.
Indeed, the wild and wonderful world of warblers is a fascinating group of birds to get to know-including our feathered friends the yellow warbler and common yellowthroat-as we get out and enjoy the great outdoors.