With their silky sleek plumage, bold black eye stripes, black chins and prominent crests, waxwings are one of our most handsome birds. We have two species of waxwings in Maine, the Cedar Waxwing and the Bohemian Waxwing. Both species can be currently found in Maine.

There are just three species of waxwings in the world. The Cedar Waxwing is restricted to North America. The Bohemian Waxwing is found broadly across the boreal habitat of the northern hemisphere. Bohemians occur in North America and across the breadth of northern Eurasia. The third species, the Japanese Waxwing, nests in southeastern Russia and adjacent China and winters mainly in eastern China, Korea and Japan.

Waxwings are so named because of the bright red, teardrops of waxy material found on some of the wing feathers and to a lesser extent on the tail feathers. The function of these wax drops is not known.

The Cedar Waxwing is a common and widespread breeding bird in Maine. During the summer, they flit from tree to tree, giving their characteristic, buzzy zirr-r-r calls. During the summer, Cedar Waxwings eat flower petals, sap and insects as well as small fruits. During the winter, fruits make up most of the diet. The fruits of mountain ash are high on their list of preferred fruits in the winter although rose hips, juniper berries, hawthorn fruits and many ornamental berries are taken as well.

Cedar Waxwings are often hard to find in Maine in the winter. Most of our breeding Cedar Waxwings migrate to more southern states for the winter, often flocking in groups of hundreds of birds. A nice flock is gracing us with their presence on the Colby campus now but will likely move south before the winter is over.

The Bohemian Waxwing is an erratic winter visitor to Maine. Befitting their name, these birds are known for their nomadic wandering in the winter in search of fruit. Bohemian Waxwings nest in western North America, mostly in Canada and Alaska. When fruit crops in western North America are poor, these birds move east searching for dependable food supplies. In some years, Bohemian Waxwings are absent; in other years, they may be abundant. Huge flocks may locate a good food supply and then depart as soon as all the fruit is eaten. Flocks of Bohemian Waxwings are generally much larger than flocks of Cedar Waxwings. More than 3,000 birds have been found in one Bohemian flock; Cedar Waxwings usually occur in flocks of fewer than 100 birds.

"Drunk drivers" can be found in groups of waxwings. Sometimes, waxwings will feed on fermented fruit. The alcohol contained in the fermented fruit intoxicates the waxwings, which then have difficulty flying and even standing when they overindulge.

The gut of waxwings is well adapted for fruit eating. The bill and esophagus are both broad enough to allow fruits to swallowed whole. Fruit eating poses a physiological demand on waxwings. Winter fruit tends to be high in sugars but low in water and nutrient content. The passage of this food through the gut upsets the water balance of the bird, forcing the bird to drink often.

The low nutritive value of waxwings' food means these birds must eat a lot of fruit to meet their daily dietary needs. The result is a rapid passage of material through the birds. The next time you encounter a flock of feeding waxwings, listen for the near constant rain of bird droppings falling on the ground.

How can you tell the two species of waxwings apart? Bohemian Waxwings are slightly larger and grayer than Cedar Waxwings. Sometimes, both species occur in the same flocks so a direct comparison is possible. However, there are better ways to distinguish the two species.

The Cedar Waxwing has wings without the yellow spots that are found in Bohemian Waxwing wings. The belly of Cedar is yellowish while that of Bohemian is grayish. However, the best mark is to look at the color of the undertail coverts. These are the short feathers at the base of the underside of the tail. In the Cedar Waxwing, these feathers are white. In the Bohemian Waxwing, they are a bright cinnamon color. It is easy to pick out this difference at a great distance, making the color of the undertail coverts the most useful identification feature.

Waxwings are often described as birds of the woods but that claim is a bit misleading. Waxwings are generally found in open woodlands, on the edges of tracts of forest or in regenerating forests where their favored fruits are abundant.

Herb Wilson teaches ornithology and other biology courses at Colby College. He welcomes reader comments and questions at whwilson@colby.edu. Previous columns and other information on Maine birding can be found at his blog: http://www.mainebirds.blogspot.com/