Friday, July 31, 2009

Bad Photos of Ugly Birds, Part III

[I should note that a good portion of the Bobolink section of "Bad Photos of Ugly Birds" series was originally written for an article that appeared in a shorter version in Black Swamp Bird Observatory's publication Dendroica sometime around 2006 or 2007. Here is a list of sources that I've taken some of the information from for these posts. All of these are available via libraries or the internet:

Sources:

Birds of the Toledo Area. Ohio Biological Survey. Columbus, Ohio.

The Bobolink. Fall 2004 issue.

Campbell, Lou. 1968. Birds of the Toledo Area. The Toledo Blade Company. Toledo, Ohio.

Johnsgard, Paul. A. 2001. Prairie Birds: Fragile Splendor on the Great Plains. University Press of Kansas. Lawrence, Kansas.

Martin, S. G., and T. A. Gavin. 1995. Bobolink (Dolichonyx oryzivorus). In The Birds of North America, No. 176 (A. Poole and F. Gill, eds.). The Academy of Natural Sciences, Philadelphia, and The American Ornithologists’ Union, Washington, D.C. (also available via subscription to The Birds of North America, online version).

Peterjohn, Bruce, G. 2001. The Birds of Ohio. The Wooster Book Company. Wooster, Ohio.

Pettingill, Olin Sewall, Jr. 1983. Winter of the Bobolink. Audubon 85(3): 102–109.

Sibley, David, Chris Elphick, John B. Dunning, Jr. 2001. The Sibley Guide to Bird Life and Behavior. Alfred E. Knopf. New York.]

Part III:

By mid-July, molting adult Bobolinks take on a motley, harlequin-like appearance and are a crazy quilt of yellow pin feathers, fresh buff-yellows, faded browns and blacks, and speckled whites. Female molt is similar, though it doesn’t seem at a casual glance to be as dramatic as that of males, given that alternate-plumaged females are more subdued in color to begin with.

Bobolinks actually never entirely lose their tails, but they do molt their tail feathers in rapid succession, leaving them with stubby tails until the replacement feathers are fully grown. The female in the photo below is replacing her middle rects:

(Adult female Bobolink. 17 July 2004)

The next photos are of birds that are often called juveniles by observers. But they’re both adults.



The Bobolink in the top photo shows fresh tertials and wings, though the tail is yet to grow out fully. The lower bird has fresh wings, but, again, the tail feathers have not fully grown out. Either birds could be confused for "tail-less" hatch year birds, fresh out of the nest. Both birds were photographed on 25 July 2004.

During the molting period, Bobolinks form mixed flocks of males, females, and young birds. Toward the end of the molting process in early-August, these flocks become very “flighty” and spend a great deal of time flying to and from different parts of the field, their tell-tale metallic “pink-pink” calls serving as the best way to track them as they bound here and there through the grass. While Bobolinks in juvenal plumage are just as distinctive in their own way as adult male and female Bobolinks in alternate or breeding plumage, juvenile birds molt into their first basic plumage shortly after leaving the nest. The gorgeous, lemon-yellow underparts, cinnamon stippled flanks and upper breast, and scalloped upperparts of juvenile Bobolinks are rather quickly exchanged for a plumage that is very similar to the basic or “nonbreeding” adult plumage. (Photos of Bobolinks in true juvenal plumage are hard to come by).

(Hatch-year Bobolink in juvenal plumage. It will soon begin a molt of its own, into a more "adult-like" basic or "nonbreeding" plumage. 3 July 2004)

Once they molt, it is difficult to separate hatch-year birds from adults when all the birds are in basic plumage. Though in the hand, it is rather easy to do so, in large part because hatch-year Bobolinks in basic plumage retain their juvenal wing and tail feathers, whereas adults go through a complete molt and have fresh wings and tails in late-summer and fall.


Adult Bobolink near the completion of his or her molt, 3 August 2004. The tail feathers are still a little uneven.

Part IV and conclusion to come . . .

Thursday, July 30, 2009

Bad Photos of Ugly Birds, Part II

Bobolinks are unusual among passerines in that they undergo two complete molts each year: once on their austral winter grounds south of the equator in the Pantanal region of northern Argentina, as well as portions of Brazil and Paraguay, where they are considered an agricultural pest due to their voracious appetites for rice and grain crops; and once on their breeding grounds in North America. Both molts take place prior to their lengthy northward and southward migrations, which combine for some 20,000 miles of travel round-trip. At this time of year, Bobolinks are well into their molt into basic plumage, if they have not already completed the process.

Male Bobolinks in alternate or "breeding" plumage are popular subjects for photographers. Bobolinks molting from alternate to basic plumage are not so popular. (I'd like to see photos from South America of Bobolinks molting from basic plumage into alternate plumage, but maybe that's too much to wish for . . .)

Kelly Riccetti recently posted some good photos of molting male Bobolinks at the Voice of America Park in West Chester, Butler County, Ohio on her blog. As part of a six-year-long summer bird survey I ran at the VOA, I had a lot of oppurtinities to watch Bobolinks as they molted from alternate to basic plumage. In 2004, in addition to the weekly surveys, I spent more hours than I care to admit "digiscoping" Bobolinks as their molt progressed throughout July and August, prior to the initiation of their migration to the great grasslands of southern South America.

Here are photos of a female and male Bobolink taken on 12 June 2004, during the height of the Bobolink breeding season (all the photos in this posting were taken at the Voice of America Park):




Note how worn and bedraggled the female's tail looks; in fact, she might even be missing a feather or two. All of that effort and wear and tear are put into taking care of this:


(Bobolink nest, 9 July 2005)

And, in time, one hopes, the effort leads to a few of these:


(Hatch-year Bobolink, 3 July 2004)

During the course of my summer visits to the VOA, the first evidence of dependent young usually came in early July when young Bobolinks appear, begging for food from adults. Adult Bobolinks begin molting as soon as their nesting duties are completed, with new pin feathers appearing on adult males at the VOA as early as July 3.


(Adult Male Bobolink 3 July 2004)

Adults typically delay their molt until their young are independent, but I’ve seen adult males that are clearly in the beginning stages of molt, carrying food in a manner suggesting that they’re feeding young. Additionally, the one nest I found (photo above) was revealed by an adult carrying a large praying mantis to three nestlings. This adult male showed the beginnings of the inverted yellow “U” shape on the breast that is typical of adult males in full body molt as well as new feathers growing in on his back. Adult females at the VOA usually do not show signs of molt until at least the second week of July. In his 1968 Birds of the Toledo Area, Lou Campbell noted that July 1 marked the beginning of Bobolink molt in northwest Ohio, and based on the observations of other birders in Ohio, the first week of July certainly seems to mark the beginning of Bobolink molt season throughout the state.

Adult Bobolinks molt their tail and wing feathers in dramatic and rapid fashion. It’s common to see adults with large gaps from missing feathers in their primaries, secondaries, and tails.

(Adult male Bobolink, 11 July 2004. Much of the wing is being molted and the bird is actively preening. Note also the new yellow feathers on the breast.)

Though Bobolinks are never rendered flightless during their molt, they do become flight impaired. My experience at the VOA has been that during mid-July, when many adults are in active molt, they become far less conspicuous and take extra efforts to stay in cover.

(Adult male Bobolink. 10 July 2004. The tail feathers are uneven and there are a number of wing feathers either missing or not yet grown in.)

Still, a few molting adults of both sexes can often be viewed at length, particularly at first light, while they busily peck, pull, and preen their mottled mix of old alternate feathers and new basic plumage feathers. This secretiveness might be part of the reason that some reports note a lack of Bobolinks in July in fields where they had been so numerous in June. I suspect that unless the field has been mowed, June’s Bobolinks are merely staying low and keeping quiet in July.

Part III will cover "tail-less" Bobolinks as well as some hatch-year birds.

Saturday, July 25, 2009

Friday, July 24, 2009

Bad Photos of Ugly Birds, Part I

I ran a weekly bird survey during the summers of 2001 through 2007 at the Voice of America Park in West Chester, Butler County, Ohio. The grassland birds that breed annually and reliably at the VOA are Savannah Sparrow, Bobolink, and Eastern Meadowlark. Sedge Wrens are irregular, occasional nesters/visitors, usually arriving at the site in early July. However, they haven't been found at the park (to my knowledge) since 2005.

Henslow's Sparrows bred at the VOA from 2002 through 2007, seemingly skipped 2008, but returned sometime in the summer of 2009. Kelly Riccetti photographed adult Henslow's Sparrows at the VOA recently during a trip she chronicled on her blog.

During my surveys, I occasionally found hatch-year Henslow's Sparrows. Here is a "digiscoped" photo of one taken on July 25, 2004:

Before long, this youngster will develop an adult-like plumage, and will be basically "adult" in appearance to us field birders. A bander could age the bird, however.

Here is a photo of a hatch-year Henslow's Sparrow taken on July 11, 2004, two weeks prior to the bird in the above photo:

Until they molt, hatch-year Henslow's Sparrows lack the double malar stripe and streaked breast of the adult, and are generally "buffier" and plainer in appearance. Sometimes, with good views you can see the yellow gape at the corners of the bill on hatch-year birds. If you're lucky, you'll find hatch-year birds being attended to by adults, as were the two birds in the above photos.

Adult Henslow's Sparrows are generally easy to identify. Here's another digiscoped photo of an adult taken on July 11, 2004:

This bird is rather worn, and by mid-July, most Henslow's Sparrows are sporting clearly worn-out feathers: bleached, abraded, and frayed. On July 25, 2004, a friend and I had the good luck to see an adult Henslow's Sparrow in the midst of molting. By itself, this would have been a very confusing bird. But on this day, it was with other obviously adult Henslow's Sparrows, and the hatch-year bird in the photo from July 25 was tagging along as well. Here are two views of an adult Henslow's Sparrow during its molt:


The fresh scapulars, coverts, tertials, wing and tail feathers, and the bright eye ring are really evident on this individual.