Springtime will make your hare stand on end

ELISABETH M. BROWN

It’s a very rabbity spring in south Orange County. When they have

food, water, and shelter, they multiply. UC Irvine has always had an

abundance of rabbits; in the morning, there are rabbit droppings on

sidewalks and pathways; in the afternoon rabbits emerge from the

shrubs to gambol on the lawns. They’re great grass trimmers, happily

creating crop circles on lawns.

In my garden there’s a rabbit on the back lawn in the mornings,

One day I stepped out from the garage and something rabbit-sized

zoomed across the garden in a panic. Like a cartoon character, it was

just a blur of brown. . I let them munch; I enjoy seeing their big

translucent ears glowing in the sunlight.

We’re spending a few days in the Pacific Northwest, about 1,000

miles north of Laguna. It’s definitely spring, although about 10

degrees cooler up here than in Laguna: red and pink rhododendrons

bloom, dogwood trees burst with white blossoms, pines and firs have

new light-green growth, and grey whales are migrating north just

offshore.

The birds tell me it’s always cooler here. Instead of scrub jays

and bushtits, there are Stellar’s jays (with a black crest on the

head) and chickadees. In California, we find these birds in our

mountains.

Here, too, the wild rabbits are out and about. They’re about the

same size as our rabbits and they act like ours, but their ears are

much shorter. Now, I’m not talking here about the lop-eared domestic

rabbits you can buy in pet stores, whose ears don’t stand up. These

are wild brush rabbits with upright, but short, ears.

Long ago, biogeo- graphers noticed that similar animals vary in

certain regular ways with changes in latitude or altitude. These

became ‘rules,’ and one is Allen’s rule which states that extremities

--limbs, tails, and ears -- get shorter as you go north or to higher

altitudes.

Warm-blooded animals use a lot of their energy just to keep warm,

and long, thin ears are hard to warm. Those short-eared rabbits have

evolved in response to the cooler climate of coastal Washington

state.

This leads to the question of why rabbits have such large ears in

the first place. Is it to better hear approaching predators? If that

were the case, northern bunnies would be easier for coyotes to catch,

but their abundance argues against that conclusion.

So what else are long, thin ears good for? They act as heat

dissipaters, exposing warm blood to the air through the thin

structure of the ears. The larger the surface area of the ears, the

more efficient the heat loss.

The rabbits with the largest ears are desert hares, which have

huge, tall ears. They also have the longest legs and are extremely

fast runners.

Heat dissipaters are a great advantage to the hare under pursuit.

Their strategy is to run away by zigzagging erratically, stoping

suddenly, then freezing in place to blend in. Meanwhile, their ears

are getting rid of all the excess body heat they built up during

their frantic dash to safety.