Y Cymry
08-15-2010, 08:30 PM
Separating Long-billed and Short-billed Dowitchers remains one of the toughest field identification problems for North Texas birders. But, judging from the casual way Short-billed Dowitchers are often reported, not everyone knows this. Our problem is that the subspecies of Short-billed (hendersoni) that migrates through the Great Plains is the one that most resembles the Long-billed. There are much overlap in measurements (including the bill) and in plumage details. The vast majority of dowitchers that we see passing through North Texas are Long-billed as far as we know, but a certain number of Short-bills must migrate through each season as well judging from the thousands that winter on the Texas coast.
With practice and care the two species can be separated by subtile field marks but I am never totally confident with my Short-billed Dowitcher identifications without confirming it with the call notes. With each new little field mark or ID trick I learn and try to apply to a suspect Short-billed I still appreciate this tried and true fail-safe. Of course the bad part is that the birds don't always call on command for our benefit.
The above discussion applies to adult dowitchers whether in breeding or winter plumage or transitional molt. The one exception to this difficult ID problem is with birds of the year in fresh juvenile plumage. Juveniles of each species are distinct in plumage from one another and from adults.
I found these two juvenile Short-billed Dowitchers on Sunday at the drying beds in two different ponds, 33 and 35. Later they were found together in pond 33.
Notice the overall brightness of the birds with broad buffy margins and internal details in the back, wing and scapular feathers. The tertials are also broadly margined with internal bars and streaks. See the buffy wash across the breast and light spotting on the neck, edge of the breast and along the white sides.
A juvenile Long-billed is darker gray backed with only narrow light gray and rusty edges to the feathers of the back, scapulars and wings. Its tertial feathers are solid gray with virtually no internal markings and with thin rusty edges. It is also grayer below and duller overall.
The Short-billed in pond 33:
http://farm5.static.flickr.com/4139/4895472267_4b5ae3e281_z.jpg
http://farm5.static.flickr.com/4139/4895472267_4b5ae3e281_b.jpg
http://farm5.static.flickr.com/4123/4895472253_b154160fca_b.jpg
http://farm5.static.flickr.com/4119/4895472247_66b80f89dd_b.jpg
http://farm5.static.flickr.com/4117/4895472243_4f9857546c_b.jpg
The Short-billed in pond 35:
http://farm5.static.flickr.com/4075/4896057504_7116594b1d_z.jpg
http://farm5.static.flickr.com/4075/4896057504_99a8357767_o.jpg
http://farm5.static.flickr.com/4116/4896057462_009a85471d_z.jpg
http://farm5.static.flickr.com/4116/4896057462_009a85471d_b.jpg
http://farm5.static.flickr.com/4097/4896057470_c8c8b8462c_z.jpg
http://farm5.static.flickr.com/4097/4896057470_c8c8b8462c_b.jpg
http://farm5.static.flickr.com/4121/4895472239_2ca66083e7_b.jpg
http://farm5.static.flickr.com/4136/4896057514_f569016dc5_b.jpg
http://farm5.static.flickr.com/4118/4896057508_a825ebbbbc_b.jpg
With practice and care the two species can be separated by subtile field marks but I am never totally confident with my Short-billed Dowitcher identifications without confirming it with the call notes. With each new little field mark or ID trick I learn and try to apply to a suspect Short-billed I still appreciate this tried and true fail-safe. Of course the bad part is that the birds don't always call on command for our benefit.
The above discussion applies to adult dowitchers whether in breeding or winter plumage or transitional molt. The one exception to this difficult ID problem is with birds of the year in fresh juvenile plumage. Juveniles of each species are distinct in plumage from one another and from adults.
I found these two juvenile Short-billed Dowitchers on Sunday at the drying beds in two different ponds, 33 and 35. Later they were found together in pond 33.
Notice the overall brightness of the birds with broad buffy margins and internal details in the back, wing and scapular feathers. The tertials are also broadly margined with internal bars and streaks. See the buffy wash across the breast and light spotting on the neck, edge of the breast and along the white sides.
A juvenile Long-billed is darker gray backed with only narrow light gray and rusty edges to the feathers of the back, scapulars and wings. Its tertial feathers are solid gray with virtually no internal markings and with thin rusty edges. It is also grayer below and duller overall.
The Short-billed in pond 33:
http://farm5.static.flickr.com/4139/4895472267_4b5ae3e281_z.jpg
http://farm5.static.flickr.com/4139/4895472267_4b5ae3e281_b.jpg
http://farm5.static.flickr.com/4123/4895472253_b154160fca_b.jpg
http://farm5.static.flickr.com/4119/4895472247_66b80f89dd_b.jpg
http://farm5.static.flickr.com/4117/4895472243_4f9857546c_b.jpg
The Short-billed in pond 35:
http://farm5.static.flickr.com/4075/4896057504_7116594b1d_z.jpg
http://farm5.static.flickr.com/4075/4896057504_99a8357767_o.jpg
http://farm5.static.flickr.com/4116/4896057462_009a85471d_z.jpg
http://farm5.static.flickr.com/4116/4896057462_009a85471d_b.jpg
http://farm5.static.flickr.com/4097/4896057470_c8c8b8462c_z.jpg
http://farm5.static.flickr.com/4097/4896057470_c8c8b8462c_b.jpg
http://farm5.static.flickr.com/4121/4895472239_2ca66083e7_b.jpg
http://farm5.static.flickr.com/4136/4896057514_f569016dc5_b.jpg
http://farm5.static.flickr.com/4118/4896057508_a825ebbbbc_b.jpg