Confusing Fall Warblers at the Reservoir

Blackpoll Warbler

 Yesterday morning I stopped by Chestnut Hill Reservoir to see what I could find of fall migrants. When I first scanned the water I was a little surprised to find exactly nothing on the water. While something could have been hiding at the far side, I couldn't make anything out. The only thing close was a gull sitting on the little patch of rocks. So I headed up the hill behind the ice rink with warblers on the brain. Some blue jays were calling but the only other sound was that of squirrels munching on acorns and then tossing them down, nearly on my head.

Around the back of the hill things started to get a little better as I stopped to investigate a call note. As I was peering though the branches trying to resolve the bird, a beautiful Red-tailed Hawk came soaring down the trail and up into a tree. I know that owls are supposed to be the silent birds of prey, but this Red-tail was certainly stealthy.

Blackpoll Warbler

As I turned my attention back to the call note more movement was discernible. A beautifully plumaged male American Redstart was skulking up in the branches never giving a clear view. But who else could have that pattern of black an orange? After he headed off, the call note came closer to reveal what Rodger Peterson referred to as a confusing fall warbler. Now looking back I'm sure it was a Blackpoll Warbler.

I carried on around the reservoir picking up some Black-capped Chickadees and Tufted Titmice before I made a point to check out the rocks for potential shorebirds. The full turned out to be a Ring-billed Gull (later many more and a Herring Gull would join it). There were also two sleepy Mallards among the rocks and a pair of Spotted Sandpipers who were in winter plumage and lacking the telltale spotted breasts.  I always enjoy watching Spotted Sandpipers up close to watch than bobbing their tails as they search for food.

Yellow-rumped Warbler

When I got to the peninsula I suddenly came across a whole flock of migrating warblers. As none of them were in brilliant breeding plumage again they all fell into the confusing fall warbler category, at least it felt that way. I started to pick out details on the most common type in the flock. White wing bars on gray wings, yellowish green, streaking on sides, eye line, white under-tail coverts. It took me a little while when I got home to go over the guide books, but I'm pretty sure the vast majority of my confusing fall warblers we Blackpolls. They seems to be everywhere! Looking at photos later helped even more to pick up on more details like leg color and see the yellow on the foot (click to enlarge pictures). After being able to recognize this one type, I started looking for birds that were different. One I thought might have a faint chestnut hue to the sides like a Bay-breasted, but that was probably just wishful thinking.

Palm Warbler

Other warblers did start to appear though. The Yellow-rumped warblers were quite easy when they would flash their diagnostic rumps, but they were a little confusing with out that field mark. Through the streaks on the breast and the little yellow shoulder patches helped the identification. I also noted the dark gray face with week eyebrow and light throat that extends around the neck a little. Fortunately the Northern Parulas were not very confusing at all, the gray back with green patch across the center was unmistakable, especially when combined with the yellow throat and white wing bars. A Black-throated Green Warbler was also present wasn't much of a challenge with the streaky black bib and brighter facial markings. 

Palm Warbler

My next challenge was a little brown bird with yellow under-tail coverts. As the two best candidates for this field mark are Common Yellowthroat and Palm Warbler. Yellowthroat was eliminated as this bird lacked the yellow throat and the back was warm brown instead of an olive brown. Palm warblers can be divided into Eastern (Yellow) and Western forms. The Easterns have extensive yellow underneath and in the supercilium (eyebrow) while Westerns have the yellow mostly restricted to the under-tail coverts. I was fortunate get a few bad shots of this bird and to me looks more like a Western but I'm not completely sure. I was hoping that someone might have thoughts on this identification. In the spring most of the birds migrating along the Atlantic coast and Eastern states are the Eastern/Yellow type but in fall we can easily find Westerns as well. Also, Western Palms tend to migrate earlier (September) and the Eastern/Yellow variety, which may also help point to a Western.

Eastern Wood-pewee

Mixed in with the warbler flock was a Downy Woodpecker and a flycatcher. I think the flycatcher is an Eastern Wood-Pewee, but unfortunately I've come to rely on vocalizations so much for my identifications and this was a silent bird.

Overall it was a great Fall morning with lots of fun with migrating warblers. I also found this really helpful and simplified view on confusing fall warbler identification from the McGill Bird Observatory. I'm looking forward to my next chance to get out and practice my confusing fall warblers!