Yes....they are a Warbler. Good, we have that to begin with. But what type of warbler are they? The species? Anyone?
This was the dilemma that faced me the other day as Deb and I were at the Delaware Water Gap. A beautiful, yet humid day at 7am. Only in the 60's but Humid. How is that? Only in New Jersey. Yet the day 'sunnied' up a bit and we made it into the low 80's at the Gap, and still humid.
If you are familiar with the Gap, you are aware that it extends quite a long ways and the Jersey side is the only side worth birding. Old Mine's Road has a birding reputation and we experienced just that. Deb and I birded the morning till around 10, when we went to Hainseville General Store for a three-egg omelet with spinach and Cheese, prior to me dropping Deb off at an Art Workshop at Luna Parc (awesome place, see Website connection).
From that point on, I was on my own. I birded between Dingman's Crossing and Milford, or the upper part of the Gap. It is only about 8 miles in length and there were hardly any motorcars, so...perfect birding from the road. Now at this point, this needs to be separated here a bit between the Everyone's and the No-ones. EVERYONE who birds a new spot will usually have a target species in mind. As I did with the Cerulean Warbler. I had it down visually. I knew what it looked like and dag-nabit Deputy Dog, if the Cerulean was there, I was going to find it. That is, 'if'...'if', if it presented itself to me. Otherwise, I had a great learning 'lead-up' as I prepared myself for this treasure.
But NO-One....No-One goes to a birding site prepared for what they are not expected to see such as rarities or hybrids or birds 'blown by the wind to and fro'. So I found myself in the No-One category. It was on my second loop of the Water Gap making myself down from Milford. I got out of the car and just started looking high in the trees for movement. But about mid-height I saw a bird fly across the road to a tree and begin to rummage around. My bins were on the bird and recently Deb and I had found a Chestnut-sided Warbler among others, so who knows....perhaps the Cerulean?
No such luck but luck enough..... I found the bird on the left (see image above blog). Fairly interesting. Yellow cap, black eye stripe....yellow smudge on the breast and gray for the breast and rest of chest. Perfect...should be an easy find in the book but what is it? It appeared to me to be a Warbler. I took out my traveling companion Kaufman and looked it up. Nada.... yes, nada..... According to Kaufman there is no such bird and yet there it is in front of me. I am seeing it right, right? Right, I am.
I only had the Kaufman with me and little or no Internet, so what am I seeing? It isn't a Blue-winged Warbler but golly man, it looks a lot like it with the exception of the overall grayish and lack of total yellow breast. It isn't a Golden-winged but according to Kaufman there is a Hybrid of these two birds. The image in Kaufman didn't resemble what I am seeing though, but I 'assumed' I was looking at a Brewster's Warbler. I even texted Lester my find and my assumption.
It wasn't until after the day was done birding that my hunch paid off. Yes, it was the Brewster's Warbler....a Hybrid of the Blue-winged and Golden Winged and occurs in areas where the two species overlap.
As I looked on the Internet, the image of what I saw....came into full view. I am still not sure what Kaufman's image represents though. But the image 'above' on the left is exactly what I saw...bingo. Doing more research I pulled out my dad's old 1947 Tory Peterson's and like 'sure-fire', there it was. On plate 50 was an image of the exact Brewster's Warbler.
Looking at the Sibley....bingo again. There it is on page 428 of my version of Sibley. The Brewster's Warbler. It is followed by the image on the right (above) of the Lawrence's Warbler.
Now you see.....you see....... that in pure scientific hybird talk, there are what is labeled as Dominant and Recessive genes. According to Sibley and Peterson and others in the bunch, when the territory of the Blue-winged and Golden-winged overlap, they can breed with the dominant bird off-spring being the Brewster's while the recessive bird being the Lawrence's.
But it doesn't stop right there.....I am happy I found a new 'lifer' species for me. Totally elated as I celebrated with a piece of pie from the Hainesville General Store after I picked up Deb at 4:30 (they close at 5pm and the prices of the pies were not in the half-price, end of day category so we paid full price but it was well worth it).
Peterson actually has a bit more narrative within his explanation but to quote him " There is a good deal of variation, some individuals have white wing-bars, some with yellow and some are tinged with yellow below. The thin black eye-mark as in the Blue-wing,and the white or largely white, instead of solid yellow underparts are diagnostic (of the Brewster's)."
Peterson also goes onto say that the 'voice' of the Brewster's (or for that fact, in the Lawrence) can be either the Blue-winged or Golden-winged. So the species itself has a borrowed voice from the parents and can be 'one or the other'. How odd.
Even odder.....according to Sibley.....first generation hybrids always appear as the Brewster's Warbler. Other research shows that the Warbler might shift from the Brewsters (left picture) to the Lawrence's (right image). And to further add confusion, according to the Classic Collection of North American Birds, state "that over a number of years, through breeding will return back to one of the original two bird species (Blue-winged and Golden-winged)".
I think Sibley sums it up best when he states "Scientific interpretations of these situations continually change as more data are amassed and species concepts evolve."
So the questions arise as more research is done on this hybrid but, ...it is a bird, is a species according to the ABA but does it evolve back from one species to the original parents and if so, why is it a new species to begin with? Or do some evolve back via subsequent breeding while others do not? The exact 'visual' of the Brewsters or Lawrence's'...while apparently known might not be known as variance occurs as Peterson notes. The song is 'one or the other' ...
So yes, Sibley at least has it right..... the data continually changes the look and knowledge base. I for one am just happy I added a lifer.....and more importantly was on my own.....able to correctly determine that some hanky-pankiness (don't you love that word....kind of like the word 'naughty'), is going on. I feel great that I correctly visualized the bird in the field and even ID'd the bird according to whatever information I had. Nice going jim......
eBird findings of Brewsters (click link).