Wings on the River: The squirrel’s word for “hawk”

In the late 1970s, Daniel Leger and Donald Owings studied this special alarm language of some of the Pacific Northwest’s most widespread ground squirrels. They recorded alarm calls in the field and in the lab, and analyzed them as sonagrams. (A sonagram is a computer-generated graph that plots sound frequency against time, turning sounds into shapes and precise data that can be helpful for identifying bird or animal species, analyzing songs, and revealing otherwise mysterious behavior.)

They documented several groups of calls, with “chatters” and “chats” — often elicited by ground-dwelling predators — and “whistles” elicited by flying menaces, like hawks. Particularly angry or frightened squirrels call faster and longer, and their chatter-chats “contain more frequency modulation,” giving them a sort of aural texture.

Owings and Leger played recordings of these calls back to the wild squirrels. The rodent’s response indicates, to me, that they knew each alarm type meant different types of danger. Hearing a recorded “chatter-chat,” they ran away, then sat up on their haunches and peered around — looking for the alleged coyote or bobcat, presumably. Hearing a “whistle” call, squirrels also ran away — then walked around, not assuming upright postures until two minutes later.

Leger and Owing’s studies are from 1978, well before the splitting up of the “California ground squirrel,” as every spotty-backed singed-brown squeaky ground squirrel in the lower Northwest was once named.

Our local ground squirrel of Oregon, southern Washington and northern California is now named the Douglas ground squirrel (Otospermophilus douglasii). Because recently, taxonomists decided that California grounds squirrels actually comprise more than one species and began separating them out.

So I don’t know for sure if our local species announces raptors a bit differently than, say, a ground squirrel in coastal California.

But these squirrel species aren’t unique. Elsewhere in the West, scientists caught Belding’s ground squirrel responding to aerial and ground predators with separate, specific calls.

But squirrels aren’t impossible to fool. I’ve heard them squeal “FLYING PREDATOR!!” when our local Wild Turkeys coasted down the squirrel’s favored hills, scrawny foot-long necks extended.

Well, I can understand that. A turkey on one of its rare, coasting flights is lightning-fast, four feet across and shaped like a coal-black dinosaur — a heron-necked, broad-bodied, fan-tailed missile that rattles the very air. The low, military-jet-like roar of a turkey, zooming low over the twilit oak savanna, has certainly scared the breath out of me more than once.

Although, even if a plant-, insect- and berry-pecking turkey wanted to eat squirrel, I doubt she could catch a healthy adult squeaker.

But always, a squirrel’s high pure squeak is an accurate indication that interesting birds are around. Hearing it, I look to the sky — for a Red-tailed Hawk stooping behind the trees, those two Bald Eagles quarreling in flight, a low-flying predatory raven, a monstrous oh-my-god-wait-it’s-a-turkey, or a soft mysterious shadow losing itself in the forest, never to be known.

For a practical guide to learning “deep bird language" — the sounds and behaviors of bird and mammals in response to predators and each other, which can tell a quiet and experienced listener about hawks and bobcats and foxes they never even see — try the book “What the Robin Knows,” by Jon Young. Or just go squirrel-watching.