Posts Tagged ‘Woodpecker’

Crazy Bird Bills


Tuesday, January 17th, 2012

Hairy Woodpecker by Joann Ecker

Imagine a Hairy Woodpecker with the beak of an American Woodcock. That’s the photograph that greeted me when I opened an email last week from my friend and ultra-observant naturalist Jo-Ann Ecker. The freak woodpecker has been visiting her suet feeder and despite a wild bill, appeared to be healthy.

Hairy Woodpecker by Joann Ecker

Scattered reports of bill deformities are to be expected, but a sudden and large outbreak in a region can be a sign of a much larger ecological problem. In the 1970s there were high rates of crossed beaks and other malformities in Great Lakes waterbirds, later linked to organochlorine contaminants. In the 1980s agricultural runoff that contained high levels of selenium was implicated in nestling beak deformities in southern California.

Odd bills are usually quite rare for songbirds. I have capture, banded and released thousands of songbirds over the years and I can only recall handling one bird with a deformed bill. After banding a Gray Catbird with a grossly crossed bill in 1993 at the Rogue River Bird Observatory in Michigan, Julie Craves, an ornithologist and fellow Audubon Guides blogger, examined published rates for songbirds and found them to be variable but generally low.

Hairy Woodpecker by Joann Ecker

Recently, ornithologists in Alaska have documented an unprecedented number of bill deformities around the state, which has extended southward along the Pacific coast into Washington.

“The prevalence of these strange deformities is more than 10 times what is normally expected in a wild bird population,” said research biologist Colleen Handel to the Associated Press.

Handel and her colleagues recently published an article in the American Ornithologists’ Union journal, The Auk, which described their findings. Over the last decade they documented 2,160 Black-capped Chickadees and 435 individuals of 29 other species of birds with grossly overgrown and often crossed beaks. They found very few incidents of nestlings with abnormal bills suggesting it mostly occurred later in life.

A bird’s beak consists of bone overlaid by keratin, the same protein that makes up hair, feathers, claws and fingernails. The keratin constantly grows and wears away just like your fingernails. But these birds have keratin growth that is about two times faster than normal.

Hairy Woodpecker by Joann Ecker

The exact cause remains a mystery. Possible causes include nutrient deficiencies, disease or parasites, trauma, genetic abnormalities, or contaminants. Scientists are looking at all of these, but the evidence thus far seems to point to contaminants as a likely culprit, perhaps combined with some other disorder.

Meanwhile, like my friend Jo-Ann, you can help scientists unravel this mystery. Keep a close eye on the birds visiting your feeders this winter and if you see any with even a slight abnormal beak, try to get a photograph of it and report it to the Alaska Science Center.

Flummoxed by a Flicker


Thursday, February 17th, 2011

Northern flickers, colaptes auratus, are regularly seen over most of the contiguous United States. A woodpecker common to both urban and rural areas, flickers seem contented to mingle with humans or make their own living in wilderness areas seldom traveled by homo sapiens. In the winter, flickers occasionally visit backyard bird feeders, preferring suet and peanut butter.

Two sub-species of flickers wing through our woodlands: red-shafted and yellow-shafted. Yellow-shafted flickers are more commonly found in the east and far north, while red-shafted birds are the flickers of residence in the Rocky Mountains and other areas west of the plains.

Distinguishing between the genders and sub-species of flickers is usually quite simple. Males of both species have a “moustache,” a stripe of color that extends from the back of the beak along the side of the face. These markings are absent in females. Red-shafted birds display brownish hues on the top of the head and reddish lining on the wings and undertail, the coloration on the wings especially conspicuous during flight. Red-shafted males have a red moustache stripe on a gray face. Yellow-shafted flickers have a grayish crown, with yellow wing-linings and feathers under the tail and a brownish face. The moustache stripe on yellow-shafted males is black. They also sport a jaunty red crescent on the nape.

So what happens to the markings when the birds interbreed? Recently I observed a male on the eastern flank of the Rockies in Montana that didn’t fit the coloration of either sub-species. After some exasperated re-reading of my field guides, I realized it was a hybrid. The colorful fellow had the markings of a yellow-shafted bird on its wing linings and under his tail. His crown also had the appearance of a yellow-shafted flicker, but the side of his face was gray with a crimson moustache, bearing the markings of a red-shafted bird. Happy to sight this rare individual, I was even more delighted to capture his picture!

Goldenrod Golf Balls


Wednesday, February 16th, 2011

This time of year if you walk around an old field you’re liable to find golf ball sized growths on last summer’s goldenrod stems. These little brown balls have an entire food web depending upon what is wrapped up inside.

The culprit behind these odd growths is the Goldenrod Gall Fly (Eurosta solidaginis), a small brown fly just five millimeters long. The adults live for a mere two weeks. In the early summer, males perch on top of a goldenrod bud and wait for a female. When she approaches, he flicks his wings and moves back and forth enticing her to mate.

The female is easy to identify with her long, sharp ovipositor. She flies from plant to plant searching for the perfect host by “tasting” the chemistry of the plant with her feet and antennae. When a suitable plant is found, she inserts her ovipositor for further exploration. If she hits the jackpot, she releases her eggs into the terminal bud of the Goldenrod plant. She can lie up to 100 eggs.

The fly larva excretes chemicals in its saliva as it feeds on the stem causing the plant to produce a gall. After about a month, gall growth becomes noticeable on the stem of the plant. The gall has a hard corky exterior. The larva feeds on nutritious tissues inside the gall. By late summer the larva has grown and molted several times.

Before the winter cold comes, its final act is to dig an escape tunnel from its central living space. It leaves the last part of the tunnel closed until spring and retreats back to the center where it produces glycerol in its body to keep from freezing during the winter. In the spring the larva is cued by temperature to pupate and just two weeks later, the fly crawls down the escape tunnel to chew the last layer and fly away.

But there are many predators that they must avoid to make it out of the gall in the spring. A Tumbling Flower Beetle (Mordellistena unicolor) can bore into the gall and eat the larva. Two species of parasitic wasps (Eurytoma gigantea and Eurystoma obtusiventris) also prey on the larva. These wasps find galls and use their ovipositors to inject eggs into the gall. When the eggs hatch, the wasp larva eats the gall fly larva and then the tissues of the gall.

In some areas, Goldenrod Gall Fly larva can be a very important food source for birds. Downy Woodpeckers and Black-capped Chickadees can devour the contents of up to 60 percent of the goldenrod galls. If you find galls that have been opened, you can easily determine if it was a woodpecker or a chickadee. Woodpeckers with bills designed to chisel with precision tend to drill neat holes along the escape tunnel that the gall larva dug. Chickadees have small bills and they have to keep picking and picking at the gall to get to the center, making a messy and large.

There are over 130 Goldenrod species, but the Goldenrod Gall Fly is fond of two in the northeastern United States. In the mid-Atlantic region they tend to be on Tall Goldenrod (Solidago altissima). Here in New England, farther northward, they are found on Giant Goldenrod (Solidago gigantea). Galls on Tall Goldenrod are hairy as is the rest of the stem, while on Giant Goldenrod they are smooth and waxy. Why the shift in host plant farther northward remains a mystery.