'Freezing' an instinctive reaction of birds to danger

STACEY COLE February 28. 2014 8:01PM

In mid-January, a Northwood reader raised an interesting question. The subject was introduced as follows:

"I have often observed a bird or birds at our feeders who appear to be 'frozen' as in a game. They remain absolutely still for what seems to be many minutes. I've heard they know when danger is about.

"An incident this winter made me really wonder about that behavior. I watched a nuthatch clutching the suet feeder and not moving any part of himself except his eyes.

"His beak was pointed upward. His eyes darted back and forth as though he was watching something above.

"My question is: Was he really watching, seeing something that had made him 'freeze' or did some other sense warn him of danger? Even further, do birds just decide to stay still for no particular reason? I am curious."

When a hawk ventures into our backyard while birds are feeding, the birds "freeze." Rarely do they even blink an eye until all danger has passed. But it has only been on rare occasions that a hawk has made a meal of one of our avian visitors.

The term "freeze" is actually used by zoologists for a bird or other animal that becomes motionless to escape detection. The American bittern is well known for its ability to hold an erect, motionless posture, its bill pointing up, at the approach of a person. It sometimes sways ,gently from side to side, as might a cat-o'-nine tail swaying in the marsh.

The diminutive screech owls are also noted for their "freezing" behavior. Owen Durfee's notes on the subject were quoted by Arthur Cleveland Bent in Bulletin 170, United States National Museum as follows: "I had the pleasure of finding two screech owls sitting side by side on a horizontal limb. The attitude was long drawn out, the whole body being stretched to its limit, the wings and feathers held as close to the body as possible. This gave them the appearance of two long stubs, the top of the head being nearly square across. The eyes were slanted slits, and while the head was directly toward me, the body was swung sideways so as to keep the wing in front as a shield; in other words, they were looking over their shoulders. In fact, one of them, as I walked part way round them, suddenly swung halfway around, so that it was looking at me over the other shoulder. After a few moments, one of them evidently realized that it was discovered and underwent a sudden transformation; from a vertical position it quickly assumed a horizontal one of only about one-half as great in height. It thus assumed a squatting position across the branch, the feathers being fluffed out, the head a round ball, the round eyes wide open, and with one click of the bill, it flew heavily away. A few moments later, the other bird followed in exactly the same line of performances."

Freezing is an instinctive protective device utilized by small- to medium- and, occasionally by a large-sized bird as does the bittern. I doubt owls the size of the great horned and the barred owl, or eagles and most large hawks would think of "freezing," but would instead think "attack," as these hunting birds have few enemies. Occasionally, though, they are attacked by smaller birds, including red-winged blackbirds and blue jays.

These often noisy species, attack large predators that get too close to their nests or fledgling young. I have seen both blackbirds and jays appear to ride on the larger bird's backs while pecking at the back of their heads. That bothersome act frequently discourages predators from further intrusion.

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A Rumney reader wrote in part: "Thought you might be interested in this. A couple of days ago (Jan. 30) as I was looking out my kitchen window, something caught my eye. At the bird feeder out back was a very large congregation of wild turkeys. Looking beyond them I saw several more. By the time they were all by the feeder, I had counted 49, but the interesting thing was that in the group was one that was all light gray and white, almost albino looking. It had no other colors as are usually on turkeys. My neighbors had told me about seeing it in their yard a couple of days before with the other turkeys."

My good friend Ted Walski, biologist for the N.H. Fish and Game Department and head of its wild turkey program, visited and answered our reader's question. Was the light colored wild turkey albinistic? Ted's answer was "No." He said that this particular individual turkey is a genetic throwback, in that one of its ancestors was a "released game farm" bird. During those early years, all released turkeys were farm-raised as there were only a few true wild turkeys in those days. Genetic traits are apt to appear years later.

Stacey Cole's address is 529 W. Swanzey Road, Swanzey 03446.

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