WHISTLING WITH YOUR WINGS

Wednesday, April 09, 2008

Despite occasional attempts from Old Man Winter every year to keep a few signs of winter present in early April, whether it be through cold temperatures, ice or snow, there are at least two spring migrants who are undaunted by unexpected wintry conditions. If you live near a wetland, step outside your door and you will hear them on any quiet evening.

The Wilson’s snipe,( named after ornithologist Alexander Wilson), and referred to in some books as the common snipe, is a familiar bird of the wet bogs, marshes and swamps at this time of the year. The invisible sound we hear circling above us is the winnowing sound of this bird as it stakes out prospective territory. The bird’s winnowing is not a vocal sound, but rather, produced with its wings. All of us have heard goldeneye ducks or "whistlers" in flight. Other ducks have distinctive flight sounds too, even smaller birds such as mourning doves, sounds which serve as identification tools.

The courtship sound of the snipe is produced in flight by a rush of air past the spread tail feathers, and the tremolo affect of the rapidly beating wings. The performing birds usually rise about 300 feet into the air on swift, beating wings, which is one reason that the source of the mysterious sound is so difficult to spot. They then fly a very erratic course with about eight downward swoops per minute. In these swoops, the tail is spread out very wide and the wings slightly closed. The humming vibration of the tail feathers causes an interruption of air flow, resulting in the familiar winnowing sound we hear each spring.

If we listen carefully, we may also hear another mysterious series of twitters and whistles rising and falling in altitude. These belong to the American woodcock who also performs a similar nuptial flight. One has been performing nightly outside our home, usually greeting me every morning when I let out the dog at 4:30 a.m.. Unlike the winnowing of the snipe, the sound we hear from the woodcock is not produced entirely by the wings, but also includes a few vocal sounds as well. While listening to their performances, it is not unusual for these birds to perform their aerial nuptials and land right at our feet so wrapped up are they in their amorous antics.

Both species, oddly enough, belong to the shorebird family, but seldom, if ever, joining their kinfolk on the sandy beaches where the majority of shorebirds forage for food and spend much of their time. The woodcock especially is an odd bird no matter how we view him. Because he spends much of his time probing with its long bill deep in the mud, the eyes over time have enlarged enormously and have shifted to the upper side of the head so the bird can literally watch for predators over its shoulders. As a result, the brain has been shoved to the rear of the skull where it trickles down and lies upside down at the back of the head. This in turn has chased the ears around so that they now lie in front of the eye rather than behind as in most other animals.

Snipe have just arrived; woodcock, however, having been performing their nightly rituals since late March. The weather will have to warm up a bit more though before any female in her right mind is stimulated into setting on a nest of eggs callously placed on the cold ground.