Importing this read because for weeks now I have been hearing what I thought to be a shrill bird call and have been trying to track it. This morning I finally discovered the source - to my surprise a squirrel. I initially thought it was grieving. I have been hearing a lot of vicious activity (super angry screeches and rumbles) under the house where I am living which based on noises are quite possibly a turf war between cats, skunks and squirrels. Once I discovered the source a bit ago I had to hunt for this.

Fascinating mini read.

Recently, a biologist using a similar technique discovered something no one had imagined — that these bird warnings are adopted, and passed along, by completely different types of animals.

At his lab at the University of Montana, biologist Erick Greene explains how this works. A small bird spots a dangerous predator — let's say a hawk or owl — flying around. It warns other birds by making a soft, high-pitched seet call. Like any self-respecting birder, Greene can imitate this alarm call exactly.

"It's very high frequency," he explains, "and it's hard to locate."

Then there's also a mobbing call. Greene demonstrates by pressing his lips to the back of his hand and making an irritating sound like screeching tires. Birds make that call when they see a perched predator.

It brings other birds out of the trees to "mob" the predator and chase it away.

Now, Greene had watched birds do this for years when he noticed something, well, squirrelly. Squirrels seemed to be mimicking these warning calls from birds, too — taking up the alarm as soon as they heard it, Greene realized.

What's more, the squirrel's mimicry is nearly perfect, though the furry animals have a very different vocal apparatus from the one birds use.

Chipmunks make these calls, too, Greene noticed. He was astonished that mammals and birds — biological families as different as mice and magpies — would share this early warning system.