Mystery Bird: Fledgling Brown-headed Cowbird, Molothrus ater

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[Mystery bird] Fledgling Brown-headed Cowbird, Molothrus ater, photographed in Arizona. [I will identify this bird for you tomorrow]

Image: Richard Ditch, 21 June 2007 [larger view].

Date Time Original: 2007:06:21 08:39:09
Exposure Time: 1/40
F-Number: 5.60
ISO: 800

Please name at least one field mark that supports your identification.

Rick Wright, author of Aimophila Adventures and Managing Director of WINGS Birding Tours Worldwide, writes:

This bird may have been a stumper for many of us. When we find ourselves faced with a creature that we just plain don't recognize, one of the most useful strategies is to try to age the bird. Our quiz subject's short tail (with all feathers essentially the same length) and its extensive fleshy gape tell us that we we're looking at a juvenile.

The bird's youth should make us feel better about not recognizing its patterns right away: young birds often differ strikingly in plumage from their parents (or foster parents, in this case). But I think we can piece this one together.

Let's start with that short tail. It's decidedly blackish, a clue in itself, with neat, bright buffy edgings, unlike the pattern of any sparrow. The tarsi are stout and conspicuously scaled, suggesting a bird that spends a lot of its time on the ground. The wing is not strikingly long, and shows the same blackish hue and bright edgings as the tail; the back is regularly scaled.

The head seems to be remarkably small and the crown evenly rounded; the eye is dark and beady. And then there's that finch-like bill, longer and heavier than any sparrow's.

What are we looking at? A blackbird, a member of the family Icteridae. Note that apart from its feathers, every feature we've described perfectly fits Brown-headed Cowbird, one of the most beautiful and fascinating of all North American birds. Juvenile Brown-headed Cowbirds show precisely this distinctive scaled and edged pattern.

Cowbirds get an undeserved bad rap from many birders. Remember, though, that their unique breeding strategy is natural, "unintentional," and that the most frequent hosts of cowbirds' eggs have evolved their own, equally fascinating strategies for dealing with the foster chicks.

Only when a species is otherwise badly imperiled -- such as Kirtland's Warbler -- is cowbird control warranted, and even then only up to the point (now reached) that the population can be maintained by preserving and managing habitat, loss of which (and not cowbird eggs) got the warblers into trouble in the first place. Unfortunately, cowbird control is easy, fashionable, popular, and a reliable source of funds, and it is still being applied, irresponsibly and wastefully, in many cases where the cowbirds and their hosts have re-attained a natural equilibrium.

And nothing makes me madder than to see birders remove cowbird eggs from nests: not only is it illegal, but that sort of short-sighted self-righteousness ignores the fact that thousands and tens of thousands of generations of Orchard Orioles and Dickcissels and Chipping Sparrows and Warbling Vireos have survived quite well, thank you, in a special relationship with a very special bird.

[GrrlScientist note: cowbirds do maintain a watch over nests they've parasitized. When their egg disappears, they have been known to destroy the nest or young chicks.]

Review all mystery birds to date.

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Cassin's sparrow? Carolyn isn't certain about it, never having seen one. The field marks are the two-tone bill, pale throat bounded by darker lateral stripes, and the speckling from the edged feathers.

Bill structure may lead one down the Emberizid path but observers should always keep in mind the Icterids especially Bobolink and Cowbirds. Fresh fawn-colored tips to much of the plumage and conspicuous gape flange should immediately suggest a juvenile. With these two clues flipping through a field guide should quickly bring one to seriously considering a cowbird. As the image was taken in Arizona, presumably two possibilities present themselves: Brown-headed and Bronzed Cowbird. Apart from being quite dark with thin pale borders to feather tips, Bronzed Cowbird juveniles have fawn-colored shaft streaks to the back. The broad pale tips to much of the feathering in a Brown-headed Cowbird give a scaly appearance to the plumage. To those familiar with the species, the relatively short bill structure further eliminates Bronzed Cowbird. This image is a nice study of a juvenile Brown-headed Cowbird.

juninal starling, probing beak,short tail

By ;jody roth (not verified) on 10 Apr 2009 #permalink

I'm with Victor. Juvenile Brown-headed cowbird.

It's got that whole cow-bird 'jizz.' (I see far too many of them each summer.)

Juvenile starlings have more needle like beaks and a far more uniformly drab brown color.

How can removing cowbird eggs from songbird nests be illegal, when states have cowbird-management programs to trap and kill adult cowbirds? Can you point to a specific law that forbids the removal of eggs identifiable as cowbird eggs?

By anonymous (not verified) on 30 Jan 2010 #permalink

The northern population of Brown-headed Cowbirds routinely migrates to the southern US and Mexico and therefore is properly protected under the Migratory Bird Treaty Act (16 U.S.C. 703-712) which states "except as allowed by implementing regulations, this Act makes it unlawful to pursue, hunt, kill, capture, possess, buy, sell, purchase, or barter any migratory bird, including the feathers or other parts, nests, eggs, or migratory bird products."

Please note that my italicized portion covers the authorized management program of which you speak- for example, under Texas Law (Chapter 64.002. Protection of Nongame Birds), after landowners are certified through a Texas Parks and Wildlife training program, they may trap and humanely euthanize female cowbirds from March 1 through May 31 only...

as to the ethics of it's implementaion, that is a separate (and perhaps valid) discussion...

By David Hilmy (not verified) on 30 Jan 2010 #permalink

A little more clarification... there is also a special provision in the Migratory Bird Act that states: "a federal permit [but still required through the State] shall not be required to control yellow-headed, red-winged, rusty, and Brewer's blackbirds, cowbirds, all grackles, crows, and magpies when found committing or about to commit depredations upon ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in such numbers and manner as to constitute a health hazard or other nuisance..."

State and local ordinances may further define control activities. For example, in New York, the Environmental Conservation Law states "Red-winged blackbirds, common grackles and cowbirds destroying any crop may be killed during the months of June, July, August, September and October by the owner of the crop or property on which it is growing or by any person in his employ."

By David Hilmy (not verified) on 30 Jan 2010 #permalink