The mob

When an enemy approaches, many birds react with a technique called “mobbing.” Crows are famous and vociferous mobbers, ganging up and screaming at hawks or owls.

For years, scientists considered this mostly a method of chasing away predators.

But Eberhard Curio, a German scientist, wondered. He set up a special cage with two blackbirds, a stuffed owl, and a soda bottle. Only Blackbird A could see the owl while Blackbird B could see Blackbird A and the soda bottle. Blackbird A angrily yelled at the owl, while Blackbird B saw only the yelling bird and the bottle, and figured Blackbird A was yelling at the bottle. Blackbird B later taught Blackbird C to fear the bottle, and Blackbird C then taught Blackbird D, and so on.

The curious Curio concluded that mobbing blackbirds were acting as tutors, teaching birds to “know thine enemy.” So the next time you see a dozen crows mobbing a hawk, you may actually be witnessing a big outdoor seminar.

Tunnel time

The snow, so cold and lifeless itself, tells tales of unseen life. On an early morning walk after a fresh layer has fallen, you may see scores of tracks of all sizes and shapes, the record of creatures roving the night in search of food.

If the snow is not too deep or if it is melting, you may also spot narrow tunnels that curve, loop and zigzag under the crust and near the ground. They are a sign that shrews have been foraging for overwintering insect eggs and grubs. Tiny and weighing a fraction of an ounce, shrews are the hummingbirds of the mammal world. They live a high-speed existence, with a heart that beats up to 1,200 times per minute - 20 beats per second! To keep that machine going, shrews must eat up to three times their weight each day.

No wonder they wander in all weather. But unlike commuting humans, shrews probably like traveling in the snow. It helps hide their movements and sounds from the sharp eyes and ears of nocturnal predators like owls and foxes who might love a juicy shrew for a midnight snack.