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Monday, June 15, 2009

More on the strange "Cerulean"

My to my excitement I received an email from William McHale who decided to follow up my strange Cerulean and was rewarded with the incredible series of photos below. It is very clear now (to my eye) that this is not a hybrid, at least one assessable by phenotype/plumage, but that it is a male Cerulean Warbler with an injury to its left side of its face. The apparent white wing panel I thought I was seeing was actually the white outer flank feathers.

All this still leaves the question "why does this bird sing the way it does?" Allen Chartier suggested to me that an injury to its syrinx, esp. if only to one side of the syrinx, could produce such strange songs (perhaps the facial injury extends to the syrinx?). Another possibility would be that this bird learned the strange song (it is an oscine, afterall) from another bird, but what other species sings like this? I am aware of no species which sings this way.
Copyright William McHale 2009
Copyright William McHale 2009
Copyright William McHale 2009
Copyright William McHale 2009

Sunday, June 14, 2009

What age is this Common Tern?

While surveying Pointe Mouillee State Game Area on Saturday we came across a strange medium-sized Sterna tern which I am still trying to age. I am sure the bird is a Common Tern, but I am not sure how old it is. At a glance it looks much like a basic adult Common Tern, except that the lower breast and belly are gray and the cap is fully black. So I'd just call it an adult except that it has an ALL-BLACK bill, carpal bar, and dark outer primaries much like those of a 1st summer bird still retaining its juvenal outer primaries (though not as dark/worn as most 1st summers). So we appear to have a montage of features not normally shared by any one age class. To me, the bird is likely an advanced 1st summer bird which has developed an all-black crown (most if not all have less than a fully black crown according to Maling and Olsen [Terns of Europe and North America]) and gray underparts. Or could it be a retarded third calendar year?

The possibility of a longipennis Common Tern (the subspecies in the eastern Old World) was considered, a contention seemingly supported by the all-dark bill and dark legs, however this subspecies in adult plumage would not have a dark carpal or dark outer primaries, so it seems unnecessary to invoke this. Thoughts would be appreciated.

Saturday, June 13, 2009

Mystery warbler

While kayaking the Black River in Port Huron State Game Area today, 13 June 2009, I came across an unfamiliar song which sounded somewhat like (though clearly different from) the latter portion of the song of a Field Sparrow- in other words like a "bouncing ping pong ball" but without the slower lead in typically given by Field Sparrow.

But the song was coming from a largely deciduous riverine forest canopy (with some nearby upland hemlock and white cedar)- not the kind of place you find territorial Field Sparrows! With some effort I was able to get limited viewing of the bird with 8 power binoculars in terrible backlighting as it sang at the very top of the canopy, probably 60 feet high or more. I was able to see that it matched fairly closely the plumage of a male Cerulean Warbler, except that it appeared to have white "panels" on the greater coverts (because of the viewing conditions it is possible that what I interpreted as a greater covert panel was due to fluffed out flank feathers or some other cause), similar to the pattern on an adult male Blackburnian Warbler. It had the necklace of a Cerulean Warbler, heavily streaked flanks, and otherwise fully white underparts, with bluish crown and face and upperparts. The tail was short, appearing to my eye just like that of Ceruleans which I often see in similar conditions. I was unable to assess the presence or absence of streaking on the upperparts.

Here are the best photos (digibinned with Nikon Coolpix p5100 through Leica Trinovid 8X32 binoculars) and video clips (the song is clearly audible twice in both clips).

My feeling on this bird was that it was likely a hybrid Cerulean Warbler X _______, with perhaps Blackburnian Warbler as the other parent. But this is of course highly speculative. I suppose there's an outside chance that this is a normal Cerulean Warbler with a strange song, though if it learned this song I am not sure from whom it learned it, as I know of nothing that sings like this. All opinions appreciated!

For anyone interested in observing this bird it appears to be on territory (and judging by its incessant mid morning singing) is likely unpaired. It is approximately 7 miles west of and 2 miles north of the city of Port Huron. It is found on the west bank of the Black River accessed from Abbottsford Rd just south of its intersection with Imlay City Rd. This will require a 0.4 mile hike through brambly, hilly forest which will be challenging and dangerous for most birders. I would recommend wearing Carhartts and bringing a GPS receiver as well, but be advised that the closed canopy could make satellite reception difficult. If you go, please try to record the bird and get better photos, especially of the wings and upperparts, and please let me know! Here is a GoogleMap showing the exact location of the bird (43.03379N, 82.58364W):