Speaking of Nature: Confusing fall warblers: Yellow-rumped warbler

  • This adult male yellow-rumped warbler is an exquisite example of a male in breeding plumage in the spring.  Note the yellow patch on the bird’s flank. FOR THE gazette/BILL DANIELSON

  • In contrast, a juvenile female yellow-rumped warbler seen in the fall is barely recognizable as a member of the same species.  Note the faintest of yellow patches on the bird’s flank.  FOR THE GAZETTE/BILL DANIELSON

Published: 10/21/2021 10:42:19 AM

We’ve arrived at that time of year when the leaves have either started to turn colors, or they have started to fall off the trees altogether. The unusually mild weather at the beginning of the month allowed for some very pleasant time to be spent outside, but if the forecast was accurate we saw some more traditional fall weather slip in over the weekend.

Crickets continue to chirp at night, but their days are numbered. A few flowers continue to bloom here and there, but they are also facing a quickly-approaching end. For me, however, the most obvious change is the thundering silence of the landscape. Most species of our summer breeding songbirds have left and their songs no longer brighten the fields and forests. We have entered the great quiet.

That is not to say that there aren’t any birds around at all. To the contrary, there are actually lots of species to be seen at this time of year, but now the birder must switch senses. In the spring and summer one tends to detect birds by sound before they are actually seen with eyes. Now the attention changes to sight before sound … unless you really know what you are doing.

Further adding to the challenge is the fact that many of the species that continue to migrate through our area are wearing different plumages than they wore in the springtime. I compare this to the difference between getting all dressed up for a fancy dinner on a Friday night and then relaxing in sweats the following Saturday morning. Finally, there is the notion that young-of the-year birds have yet another plumage. In all cases you are “dressed,” but the appearance is very different. So let’s take a look at a beautiful bird called a yellow-rumped warbler (Setophagacoronata) and we’ll look at the difference between fancy breeding plumage and far-less fancy non-breeding plumage.

To start with, let’s consider an adult male photographed in breeding plumage in the month of May. I took this photo in the woods down behind my house and I simply couldn’t believe my luck when this gorgeous little guy stopped moving long enough for me to be able to focus on him. All decked out in fancy “black tie,” this bird is really stunning. The combination of black, white and gray feathers is real eye candy, but the final flare of bright yellow is a real “power accent.” I think of a man dressed in a tuxedo with a yellow kerchief in his pocket.

In contrast, the juvenile female photographed just last week is barely recognizable as being a member of the same species. The patterns in the plumage are still quite similar, but the colors have been changed from black and white to brown and lighter brown. There is no yellow on the head at all and there is just the slightest hint of yellow on the flanks. At one point these two plumages might have been thought to belong to entirely different species.

Also note that neither photo shows the yellow patch of feathers on the bird’s rump for which the species is named. As with the red-bellied woodpecker, sometimes the field mark for which a species is named is not the most prominent of marks. So the fall birder has a lot to sort through in order to make a good identification and the particular challenge of the warblers has been codified with the term, “confusing fall warblers.” There is no way around the fact that these guys can be diabolically tricky.

So what is a novice birder to do? The answer to that is simple, but not easy. To get good at birding you have to practice, practice, practice. I picked up on the presence of the little female when I heard the slightest of noises coming from the trees to my left. This was not a “song,” but rather a subtle vocalization called a “contact call.” Different species make little “chips” to one another as they move about the landscape and if you listen carefully you can begin to tell them apart. The lisping, “tsip” of a white-throated sparrow is quite different from the crisp, “chick” of a chickadee. Warblers have notes that are difficult to spell, but I might hazard a guess at, “chrrp” with no vowels.

And when I say practice, I mean practice. I have been birding for over 30 years and there are still things that I need to learn better. Exposure to this stuff over years and years is required to make yourself better at identifying sounds and don’t forget that many species are only seen or heard for a week in the spring and a week in the fall. That gives us a long time to forget!

You know what’s next right? This is when I tell you to go outside. There are even a couple apps for your cell phone that can help you with the different vocalizations that birds make. Look around for birds and take in as much information about colors and markings as you can. Then see if you can hear anything. When the bird finally moves off, you can then look for something similar in a field guide or a computer program. If you can find a visual match that also has similar sounds, then you may be on the right track. It’s a real challenge, but that is what makes it so much fun!

Bill Danielson has been a professional writer and nature photographer for 24 years. He has worked for the National Park Service, the US Forest Service, the Nature Conservancy and the Massachusetts State Parks and he currently teaches high school biology and physics. For more in formation visit his website at www.speakingofnature.com, or head over to Speaking of Nature on Facebook.




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