When Absence of Evidence is Evidence of Presence

by Steve Young (text and photos)

ARMN member Steve Young shares a winter bird-watching tip.

There are many times that birds will help us find predators, especially birds of prey like hawks and owls. Smaller birds will start making a fuss with vocalizations and sometimes will mob the predator and surround it, and even dive at it or chase it when it flies. Many of us have experienced this phenomenon in our yards or on nature walks, and may or may not have been aware of what was going on.

But there are other times when the very absence of activity is a sign that a predator may be nearby. Songbirds have reason to fear the bird-eating accipiters that we usually call hawks. One of the most common accipiters we see in our area is the Cooper’s Hawk (Accipiter cooperii). While this bird is a year-around resident of our area, at this time of year we get an influx of Cooper’s Hawks that migrate from further north for the winter. They are easier to spot when the trees are leafless. They also seem to specialize in staking out bird feeders where they can try to pick off some fast food on the wing.

If you know a spot where there are usually a lot of birds, whether your back yard or a favorite place further out in nature, be alert for times when the birds seem to have disappeared and it’s unusually quiet. Perhaps you will hear an occasional high-pitched, momentary alarm call. This may be a sign that a Cooper’s Hawk is in the area and its potential prey birds are hiding. This hawk likes to perch and wait for an opportunity, and you may have to look carefully for them because they can be hard to spot.

Several days ago in mid-December I noticed the almost complete lack of any bird movement around my house. The day before, the birds had been very busy, active to both my eyes and ears. But on this day, for hours I had seen and heard nothing. I assumed there was an accipiter in the area, most likely a Cooper’s Hawk. I stepped out on my front porch and heard the mewing sound of a Yellow-bellied Sapsucker (Sphyrapicus varius). I looked and looked, but could not find it. But then, about 100 feet away, I finally saw it—a Cooper’s Hawk perched in the neighbor’s maple tree, blending in, like a ghost. The bird stayed there for many minutes, motionless except for the movement of its head scanning for prey, and an occasional bit of preening. I cautiously came closer to it and was able to get several photos.

After watching the hawk for about 15 minutes, I had to turn my attention elsewhere, and it eventually left. I don’t know whether it caught the Sapsucker or something else. However, I did notice that the other birds returned to my back yard.

This is a great time of the year to watch birds on the bare trees and listen for calls, especially anything unusual. It may be a warning of a Cooper’s Hawk really close by.