Creatures courageous and cowardly

ELISABETH M. BROWN

We expect wildlife to flee when we approach. When instead an animal

stands its ground, it’s something unusual that demands attention. We

wonder if it is sick, or maybe hostile and about to attack. What’s

going on?

On my walk to work I pass small lizards sunning themselves on a

concrete path. Usually they zip away into nearby shrubs as I

approach, but recently I noticed, among this year’s crop of tiny

ones, two that stand their ground.

Why are they out there in the first place? Lizards need to warm up

in the sun so they can successfully hunt insects. Anyone who has

tried to catch a grasshopper or swat a fly knows you have to be fast.

For the lizards, staying out in the sun means a higher body

temperature, faster muscle response, and better luck hunting their

insect prey.

The downside of staying out in the sun is that they might

themselves be prey -- to crows, roadrunners, snakes, house cats or

small boys. It’s a balancing act, a game with high stakes.

Wildlife with no fear of humans is usually restricted to

uninhabited islands.

European sailors visiting the Galapagos islands noted in their

journals that the animals there -- giant tortoises, large swimming

lizards and various birds, had no fear of humans and did not flee.

The sailors found this to be a great boon, and slaughtered them for

food. The lizards tasted bad, so they concentrated on the giant

tortoises, hunting them to extinction on some islands.

Island fauna in general have no fear of humans because they have

no experience with us. A predatory bird in the sky they notice, but a

large, upright animal doesn’t push their panic button. It would be a

waste of time and energy for an animal to give up what it’s doing and

run away from something that poses no danger.

On the mainland, however, the dangers are many and real and

include humans.

The smart lizard takes few chances; it’s better to be hungry than

risk being eaten.

In every generation, some lizards are born (hatched, actually)

less timid than the rest; in coastal Orange County these are usually

eliminated before reaching adulthood. What I have been seeing in the

tiny lizards is the natural variation in the range of behaviors

before natural selection weeds out the foolish, courageous ones.

If there were no predators, lizards that bask in the sun longer

would catch more insects, be more successful, and leave more

descendants. Thus the “courageous” trait would spread in the lizard

population. Over time, more and more lizards would stand their ground

when danger approached. But in our predator-filled environment, it’s

the cowardly lizards that survive long enough to reproduce.

I don’t mean to imply from this that lizards can’t change their

behavior from experience. Even tropical fish in an aquarium figure

out where the food comes from, and when it’s likely to appear.

Lizards also have some limited capacity to learn from their

experiences, but some of them, the bold ones especially, don’t

survive that first encounter with danger.

* ELISABETH BROWN is a biologist and the president of Laguna

Greenbelt Inc.