Hi All, First, what’s the big deal about Audubon’s & Myrtle Warblers? When I was a kid starting birding in the early 1970s my field guides considered them separate species, and the adults are distinctive but clearly closely related. Many listers were disappointed when, based on studies of hybridization, the two were lumped into Yellow-rumped Warbler. There are rumors that, based on more recent science, they may get officially split into separate species again soon, and many birders have diligently kept lists of Audubon’s and Myrtle Warblers wherever they go, waiting for the day that the additional species will kick in again.
Audubon’s breeds from the Rockies westward in SW Canada and the US Lower 48. Myrtle breeds in a long diagonal swath from Alaska across much of southern Canada (except the mountainous SW where Audubon’s breeds) into the northeastern US. When they migrate, Audubon’s generally stays in the west. Most Myrtles migrate in the eastern US, but more Myrtles migrate through the western US than Audubon’s do in the east. So Audubon’s Warblers are more of a rarity to us Easterners, whereas Myrtles are something to expect and look for in migration out west, like many species of warblers for us, as I understand it. And on the west coast, both types can be found in the winter. Anyway, I’m very glad others managed to refind, and photograph, and record the bird I found this morning. When I saw it, it was on the section of the Cayuga Waterfront Trail (the paved biking & walking path) along Fall Creek between the anglers’ parking area at the end of Pier Road and the suspension bridge over Fall Creek. It was doing one of the things which Yellow-rumped Warblers most predictably do in our area in winter: eating Poison Ivy berries, an excellent food enjoyed by lots of woodpeckers (5 species were present) as well as by thrushes, vireos, chickadees, other birds, and squirrels. These fruits are gray, about 1/8” diameter, often in fluffy clumps, on branches extending from hairy red vines which cling to the trunks of large trees. Mature Poison Ivy vines are right next to and over the trail where I found both the Audubon’s-type and at least 3 of our usual Myrtle-type Yellow-rumped Warblers today. This is also where I saw my first-of-year Myrtle on 8 January. I don’t know why, but some berries and bits of vine have fallen on the pavement here. Please don’t touch them, because any part of the plant can cause skin irritation, nor move them because they are attracting Juncos to the path, and maybe the Song Sparrow I saw next to the path. Across Fall Creek in Renwick Wildwood, the area around the boardwalk and nearby trails also has many big trees hosting Poison Ivy vines, and that is where Elliott Ress and Ann Mitchell found the Yellow-rumped Warblers (both types) after I lost track of them while typing a rare bird alert. I believe that’s where Jay found them as well, soon after Elliott’s eBird report. I have seen Yellow-rumped Warblers fly across the creek before, so this location didn’t surprise me. Both Jay’s and Elliott’s photos show the bird eating Poison Ivy berries. On 9 December I saw 3 Myrtle Warblers and a 4th Yellow-rump, which I then thought to be a Myrtle, doing the same thing as I crossed the boardwalk. (Another favored winter food of Yellow-rumped Warblers in our area is the similar-sized blue fruits on Red Cedar trees, such as along the bluffs on Lake Road south of Aurora and near the bath-house at Taughannock Falls State Park.) We are assuming that today’s unusually plain Yellow-rumped Warbler is the same one which John Garrett found and photographed on 24 December, also with 3 Myrtle-type Yellow-rumped Warblers. That was about half a mile away, on the part of the Cayuga Waterfront Trail which goes between Cascadilla Creek and the Waste Water Treatment Plant near the Ithaca Farmers’ Market. Yellow-rumped Warblers have not been reported to eBird there since that day. In his photos the bird is on some other type of tree branches, and I’m not aware of any particularly attractive food source for them there. (Does the WWTP host more tiny insects than elsewhere therefor all the Ruby-crowned Kinglets and the recent Northern Parula?) What is interesting to me is the distance that the Yellow-rumped Warbler flock seems to have wandered. I first met John Garrett almost 3 years ago when we converged on the southeast corner of Cayuga Lake because a Black-headed Gull was found there that day. I think he had just arrived in Ithaca from out west to work at the Lab of O. This past Christmas Eve, when John discovered this Audubon’s type Yellow-rumped Warbler he called it “a fairly typical bird for a west coast flock” and noted its AUWA “quip” versus MYWA “chup“ call notes. Even if my own hearing were not so bad, I am ignorant of such call note subtleties. Nor do I have much experience with the Audubon’s type Yellow-rump. And it wasn’t until I saw John’s Christmas Eve photos that I realized I had not been using all the criteria to pick out Audubon’s Warblers. If I had studied my Sibley guide I would have seen the picture, remarkably like what John photographed, of a first year female whose throat was not at all yellow. I had been checking Yellow-rumped Warblers for yellow throats, which would catch adult Audubon’s, and none of the 4 Yellow-rumps I saw from the boardwalk last December 9 had yellow throats, so I called them all Myrtles. But I only recall of them 3 being otherwise boldly marked, and after seeing those photos I wondered about the 4th. It turns out that an even more diagnostic field mark is the shape of the throat patch. Audubon’s is a simple triangle, but the lower corners of Myrtle’s throat patch extend in a curve to the rear below the the cheek or “auriculars”. I hope this helps you find this bird, and want to do so. Plus it’s cute. - - Dave Nutter > On Jan 11, 2024, at 3:48 PM, Jay McGowan <jw...@cornell.edu> wrote: > > Hi all, > John Garrett found an apparent Audubon's Yellow-rumped Warbler at the Ithaca > Farmers Market on Christmas Eve (checklist), a bird which eluded observers > for some time until Dave Nutter refound it near the bridge to Renwick Woods > and Stewart Park late this morning. I caught up with it a little later today > and got some more photos, as well as a recording of the chip calls. I was > struck by John's initial photos that it was quite a dull individual, but it > was clearly not a pure Myrtle either. Seeing (and especially hearing) it in > person today, I suspect it's probably a Myrtle x Audubon's intergrade. The > chip calls were somewhat intermediate between the two but tending more > towards Myrtle, and some of the other characteristics seemed intermediate as > well. My checklist with photos and the recording is here, and I'll add more > details once I have a chance to study some more intergrades. A very > interesting bird either way, so kudos to John and now Dave for picking up on > a subtle individual. > > Also, a bird that looks good to me for a Tufted Duck x scaup sp. hybrid was > sleeping in the Aythya flock not far from the continuing adult male Tufted > Duck off the east end of Stewart Park around the same time (checklist). > > Jay > > -- > Jay McGowan > jw...@cornell.edu > -- > Cayugabirds-L List Info: > Welcome and Basics > Rules and Information > Subscribe, Configuration and Leave > Archives: > The Mail Archive > Surfbirds > ABA > Please submit your observations to eBird! > -- -- (copy & paste any URL below, then modify any text "_DOT_" to a period ".") 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