Do you know why swallows build in the eaves of houses? It is to listen to the stories. J.M. Barrie – Peter Pan, Act I.
That is not a swallow sitting on her nest under the eave of a Rocky Mountain cabin in the photo above. The best current thinking around here is that it is a female Hammond’s Flycatcher listening to the stories, but we could be wrong and invite comment more knowledgeable than ours. After all, the first three people to look at this bird all thought it was a Solitary Vireo.
But that can’t be right. Solitary Vireos are no more. So says the DNA. What birdwatchers used to call Solitary Vireos are actually three distinct subspecies, Cassin’s, Plumbeous, and Blue-headed. None are commonly found in the southern Rocky Mountains which is where this nest is.
And so, mistakes were made. But we can be forgiven. The white eye ring led us astray. Vireos have them and it is a prominent feature on this little bird.
So, what is it, that cute little bird sitting atop two nestlings?
Here is another photo to help us with our labeling exercise.
The birds don’t care what label we give them, of course. Labeling is a curiously human occupation leading to mixed results such as science or war. But we are birders and we want to know what it is we have seen.
The first clue is the Aspen sapling on which the bird is perched. That means we are in the mountains and in a mixed conifer-aspen forest. That pretty much eliminates all the vireos except a Gray Vireo or a Plumbeous Vireo. All the others live lower and in different ranges than the southern Rocky Mountains. Moreover, we know they are nesting and raising a family so are not migrants.
Range maps, by the way, are important clues for casual birders. Most birds live in the ranges indicated by the guides, especially if your guide is relatively current. (Climate change is affecting the range of many birds.) And, while it is possible the bird you just saw was out of its range, it isn’t likely, so you’ll need more evidence.
Back to our bird: The white eye ring, does not run all the way down to the top of the beak. That lets out the Plumbeous Vireo. And this little bird has two white wing stripes and the Gray Vireo has only one.
Conclusion: This is not a vireo.
The head looks as if you would like to scratch it because of that little, barely visible tuft. The tuft leads to the possibility that it is a flycatcher of some kind. (And that is some kind of fly in its mouth.)
So which flycatchers breed in the southern Rocky Mountains and have white eye rings and are as small as this bird? (Western Wood Pewees meet other criteria, but are larger than this bird.) That leaves us with four possible flycatchers: Least, Hammond’s, Gray, and Dusky. All have eye rings and two wing bars. All inhabit the southern Rocky Mountains, although Least Flycatchers are rare. In fact, the fourth and non-casual birder eliminated the Least because it mainly lives in deciduous forests, orchards, and parks. Moreover, its eye ring often extends to the top of the beak.
She also eliminated the Gray because it prefers the semi-arid habitat of the Great Basin and seldom goes higher than pinon-juniper forest elevation which is too low for Aspens.
Down to two now, she tosses the Dusky Flycatcher because its eye ring also extends too far — at least in the National Geographic, Sibley, and Kaufman field guides. (Kaufman is of the opinion that the best way to identify these flycatchers is by voice. In our defense, these two birds never made a sound that we heard.)
After announcing her conclusion, the real birder went off to run the store, leaving me, the sous-birder, to wrap it up by doing actual research on the Cornell web-site. (I have a day job, but it is not as interesting.)
From Cornell’s “Birds of North America” (BNA) I learn,
Hammond’s Flycatcher is a common but poorly known migratory species that breeds in mature coniferous and mixed forests of western North America from New Mexico and Colorado to Alaska.
Later, the article confirms that Hammonds breed in north-central New Mexico, inhabit conifer and aspen forests, at elevations above sea level varying from from 2,100 to 3,000 meters, which is where we found these birds.
Both the male and the female fed the nestlings, but only the female sat on them; exactly how BNA describes their behavior at the nest. Both were silent while feeding, also spotted by Cornell as behavior of Hammond’s Flycatchers.
Pushing the identification into the realm of near certainty, Cornell notes that Hammonds’ white eye rings are “often thicker behind eye”. Finally, we read that the upper mandible is blackish and the lower is “yellowish” at its base. The bill is shorter and more narrow than the Dusky or the Gray.
We casual observers can take comfort from this,
[Hammond’s Flycatchers are] perhaps most renowned for being difficult to identify in the field, often being confused with the Dusky (E. oberholseri) and Gray (E. wrightii) flycatchers, whose habitats occasionally overlap those of Hammond’s. Size and color differences among these species are subtle, and the songs and calls, especially of Hammond’s and Dusky, are similar enough to make field identification difficult for the casual observer.
Thank you. That makes me feel better. Perhaps the birds nested in the eaves not to listen to the stories but to listen to the people struggle to identify them. Probably with a sense of wonder that we could be so busy trying to label them rather than just stare in wonder.
We conclude with this photo of the babies.
Credit for the information from BNA belongs to James A., Sedgwick. 1994. Hammond’s Flycatcher (Empidonax hammondii), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/109
We welcome comments about this identification.