Saturday, August 15, 2009

Two Probable Dark-eyed Junco Hybrids, Junco hyemalis hyemalis X White-throated Sparrow, Zonotrichia albicollis, in Ashford, Windham County, CT

One of my true birding passions is studying juncos at my feeder. Since finding that this common wintering species and uncommon nesting bird can show a wide variety of plumage characters, I have been hooked on cataloguing the range of variation exhibited by Slate-colored Junco, Junco hyemalis hyemalis.

A bonus has been finding an occasional Oregon-type Junco in wintering flocks in Connecticut. On 14 January 2008, while photographing a beautiful presumed first-year female Oregon Junco, J. h. oreganus, at my feeder in Ashford, I found one, and then another, junco exhibiting characters that indicate probable hybridization with another common wintering species and uncommon nesting species, White-throated Sparrow, Zonotrichia albicollis.

What first attracted my attention to these birds, two of about fifty juncos using my feeders, was the presence of a pale throat. Typically, Slate-colored Juncos show a throat the same color as the breast with hatch-year birds sometimes showing a slight paling in this area. One of these birds showed an extensive pale area below the chin that extended to the top of the breast. It showed faint sub-moustachial marks reminiscent of those shown by White-throated Sparrows. The other bird showed a similar but less extensive white area in the throat. Both birds showed whitish spots in the supraloral area, again similar to where White-throated sparrow shows yellow.

Both birds showed white tips to the lesser coverts and limited dotting on the greater coverts that formed dotted wing bars resembling those shown by the genus zonotrichia. These were different than the white edgings that form wing bars in some Slate-colored Juncos.

Both birds showed brownish streaking dorsally and one bird showed buffy coloration to the bib and this bird also showed one outer greater covert that looked similar to a zonotrichia covert.

These birds were not captured so age and sex determination would only be speculative.

The one previous Junco X White-throat hybrid I have seen in Connecticut looked much more like a White-throated Sparrow. This bird, found and photographed by Bruce and Kevin Finnan, was at the White Memorial Foundation feeders in Litchfield, Litchfield County, Connecticut during the winter of 1999.

Slate-colored Junco and White-throated Sparrow are uncommon nesting species in Connecticut, with the nearest known site about eight miles north of my yard at Boston Hollow in Eastford and Union. It is conjecture, but, the presence of two birds suggests that they may have come from this area and are the product of limited mate selection for these two species.

Sunday, April 12, 2009

Black Brant, Branta bernicla nigricans, in Connecticut

For a state with a coast line, Connecticut birders get very few good looks at Brant, Branta bernicla hrota. While they can number in the thousands along shores of Long Island Sound and in the major river estuaries, the only looks we get are of birds bobbing in the waves or feeding against the various rock jetties that punctuate the shore, or of large skeins migrating high overhead.

Typical adult Brant, B. b. hrota
Brant, B. b. hrota

Still, I have been looking for a Black Brant for years, hoping against all odds to see one of these western birds mixed in the flocks. It hasn’t been easy.

On 10 April 2009, Nick Bonomo, doing the work of an active and skilled field birder, located an adult Black Brant off the coast of Short Beach in Stratford, Fairfield County. This bird was with a thousand or so Brant that had been frequenting the jetties and mud flats at the mouth of the Housatonic River where it meets the Sound. The weather was deteriorating when he found it late in the day and the light was fading fast. The next day was even worse with a mixture of sleet and cold rain making observation a chore at best. I relocated the bird on 11 April 2009 in the same general location Nick found it the day before. It was with a few hundred Brant about 300 yards offshore. I managed a few poor digiscoped images before the bird flew around into the mouth of the river and eventually re-appeared on the sand bars off of Milford Point, New Haven County.

Black Brant, B. b. nigricans, 11 April 2009 Stratford, Connecticut

This bird was a typical Black Brant, showing the bold white collar that nearly encircled the neck, unlike the small broken collar of eastern Brant. On the water, it showed a bright white area in the rear flanks that contrasted with a very dark back and chest.

Out of the water, the dark, nearly blackish collar joined the dark breast creating an all-dark look to the front of the bird. This darkness continued down under the bird between its legs and to the lower belly, stopping at the white under tail area. The Black Brant seemed more robust that the other brant present.

Black Brant with Brant, hrota

Black Brant in Ripley Waterfowl Conservancy collection, Litchfield, Connecticut
Looking back through my records I found a very poor image of a brant I digiscoped off of Shippan Point, Stamford, Fairfield County, on 17 March 2003. This bird was tentatively identified as Gray-bellied Brant, Branta bernicla ?, a form whose range includes the high arctic and Melville Island that winters in Puget Sound. This form, possibly a fourth subspecies of Brant ( Brant hrota, Black-Brant nigricans, Dark-bellied Brant bernicla) or part of a hybrid population between Black Brant and Brant, is not fully understood. There are a few recent records from Long Island that may pertain to Gray-bellied Brant.
(see for a discussion of Brant subspecies identification and of Gray-bellied Brant)

While similar to Black Brant, this bird showed more contrast between the breast and the black neck stocking and showed a smaller white patch at the sides of the neck and not the nearly complete bold collar of Black Brant. The white at the rear flanks was not as crisp as appears on Black Brant. The bird was significanltly darker below than should be shown by eastern brant, hrota.

Likely Gray-bellied Brant, B. bernicla (?), Stamford, Connecticut, 17 March 2003