Saturday, June 26, 2010

Cedar Waxwings: Silk-Tailed Birds of the Cedars

Every day for the last three weeks or so, the air has been filled with the thin, high pitched calls of cedar waxwings (Bombycilla cedrorum). Highly social birds, they flock together year round as they forage for food in their favorite haunts. Lately these haunts have been the yards and lawns around town, where daily I see their heads popping up from the grassy carpets, peering at me with their beady eyes while they assess whether my presence is threatening or not.

From the first time I saw a cedar waxwing, I fell in love with it. Its feathers are so sleek that they blend together to form a whole, making the bird look like something made of silk or satin. In fact, the name Bombycilla was coined in an attempt to reflect this: silk-tailed. Add to the fine-textured caramel-colored body a jaunty crest, a black mask, a yellow stripe on the tail and wings tipped with “red sealing wax”, and you have one dapper bird.

I recently found a deceased waxwing on the side of the road and had the chance to examine it in great detail. Those bits of red on the wings really do look like someone dripped sealing wax on the ends of the feathers. In truth, however, each red “thing” is merely a flattened extension of the feather’s shaft. It is quite stiff and does feel waxy.

People have speculated for many years the reason(s) for these decorations, and in the 1980s a theory was put forth that the birds use them to assess each other for potential mates. Apparently the number of “droplets” reflects the age of the bird: more droplets means greater age. It seems that the birds select mates who share the same number of droplets as they sport, thus mating with individuals that are the same age. It seems as good a theory as any.

Several years ago, I had a friend who had a parakeet. She had to be sure to provide the bird with red or orange foods to keep its color optimum, otherwise it faded to a pale yellow. Likewise, flamingoes that don’t eat enough shrimp start to loose their pink coloration. The same seems to hold true with the waxwings. Back in the 1960s birds started to show up in the northeast with orange-colored wax droplets instead of red, and orange tips on their tails instead of yellow. It turns out that this color change coincided with the introduction of non-native honeysuckles. The red wax droplets are colored by the presence of certain carotenoid pigments found in the birds’ regular food. The birds eating the foreign fruits consumed different carotneoids and ended up with differently colored feather tips.

Cedar waxwings are one of the most serious fruit-eating birds we have. Most of the year they dine on fruits: cherries, serviceberries, winterberries, dogwood berries, hawthorns, mountain ash, et al (note that all these fruits are red). These small fruits are inhaled whole and digested with such rapidity that the seeds pass right through the birds’ digestive tracts. When fruits are ripe, the flocks sweep in, take a seat on a convenient branch and start gulping them down, although sometimes they will hover mid-air and pluck the fruits. A tree or shrub can be stripped clean in a day or two, and then the flock moves on.

A classic waxwing behavior, and one every bird photographer has captured, is the passing of a fruit from bird to bird. Sometimes this is done between members of the flock, until one bird decides to eat it. Other times it is done as part of a courtship ritual, where the male presents the female with a fruit. She in turn takes it and hops away, contemplating the gift. If she is impressed, she hops back and gives the fruit back to him. This little ritual repeats until the female decides to eat the fruit (or not). Apparently fruit consumption is equivalent to accepting an engagement ring. Shortly thereafter, nest building begins.

By the time late spring and early summer roll around, however, there are few, if any fruits, left for the birds to eat. When this happens, these birds don’t starve and fade away, they have a back up plan. They change their diet to insects. And just as they eat fruit like there is no tomorrow, so, too, do they gorge on insects. This can be quite the boon when insect pests are around, for a flock can go through an insect population like wildfire through a drought-stricken forest. I’d be willing to bet that this is what all those waxwings on the lawns have been doing for the last few weeks: hunting down insects to fill their bottomless bellies. Sadly, this single-minded behavior can get them in trouble, for flocks foraging along roadsides can get run down by passing cars and trucks, like the waxwing I found yesterday.

If you find yourself walking along a forest edge, or a grassy field near a woodlot, keep your eyes and ears open for waxwings. You are bound to hear them, and when you do, it is only a matter of glancing around before you find the source of their distinctive sound.

Photo Courtesy Wikipedia.

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Ellen Rathbone

Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.



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