Far More Than Creatures of Habit
BAKER, Calif. — Among the tortoises -- out in their Mojave Desert kingdom of arroyos and burrows fringed with creosote -- the hormones were running high.
Among them was an old male courting so many females that scientists dubbed him a “cad.†An unusually cooperative female they called a “hussy.†Then there was a bully who thrashed competitors, but was no stud, and a huge female who showed little interest in guys.
Recent dawn-to-dusk observations have led U.S. Geological Survey biologist Kristin Berry to the provocative conclusion that Gopherus agassizii is anything but a slow, dull homebody. Tortoises don’t just demonstrate behavior, she says, they show personality.
“They are not the same inside their shells; they are individuals interacting in complex communities,†she said. “And there may be behavior occurring in ways we haven’t yet learned to observe, or interpret. How does a tortoise exhibit joy, or play, or express frustration?â€
Asking such a question was once heresy in scientific circles. But Berry and a growing number of researchers are rejecting the decades-old notion that nonhuman creatures are instinctive automatons devoid of feelings.
Where even some skeptical scientists were comfortable acknowledging that dogs, dolphins and chimpanzees show signs of personality, this new field sees a spectrum of temperament and emotions among almost all animals: octopuses and lizards, crayfish and spiders. Even fruit flies.
“Ours is a holistic view,†said Andy Sih, a biologist at UC Davis, which has become a major center of research into what Sih prefers to call “behavioral syndromes in animals.â€
“Some scientists study bird songs, or prey behavior, or mating behavior. We are saying they are all related,†he said. “Individuals who are aggressive toward other males, for example, also tend to be more aggressive in their hunting styles, and more coercive rather than nice toward females.â€
“It makes things a lot more complicated,†he added, “but if that is the reality, you have to account for that.â€
His colleague, biology professor Judith Stamps, was more blunt: “Instinct is out of favor.â€
“This field opens us up to thinking that there are other life forms as varied as we are,†she said. “Anyone with a dog or a cat at home knows this. In some places, it is important to be shy. In other places, it pays to be aggressive. Animals that live in groups might work better with a combination: some attacking, some laying low, others finding food.â€
That kind of talk is nothing new. Even Charles Darwin argued that emotions exist in both humans and animals.
But in the 1930s, to avoid anthropomorphizing, scientists began focusing on how animals react to stimuli, rather than broader personality traits, such as a tendency among certain alpha male tortoises to fight all day long.
All that began to change in the 1990s, when it become acceptable again, as UC Berkeley biologist Samuel D. Gosling puts it, to think of personality traits in animals as a reflection of behaviors that persist over time and in different situations.
Gosling mapped the landscape of personality in captive spotted hyenas, for example, and discovered five basic dimensions: dominance, excitability, sociability, curiosity and tolerance of humans.
“If we are to take evolution seriously,†he said, “it would be a disaster to think that personality suddenly emerged when humans departed from chimpanzees.â€
Even colonies of brainless sea anemones fight as organized armies with distinct castes of warriors, scouts and reproducers, according to a new study by David J. Ayre from the University of Wollongong, Australia, and Richard Grosberg from UC Davis.
“Some have better memories. Some are more aggressive. Some are wimps,†Grosberg said. “So, do sea anemones have personalities? Sure enough.â€
Implications of animal behavior that goes a step beyond what can be quantified ruffles the feathers of biologists who insist that data be repeatable in controlled conditions.
Among the skeptics is Peter Marler, professor emeritus in behavioral neurobiology at UC Davis, whom younger colleagues respectfully refer to as the alpha male of traditional animal behavior research.
“It is very difficult to develop a means of measuring personality and temperament in animals in a repeatable way,†Marler said.
“So when you start talking about animal friendliness or shyness without an objective index to measure it,†he added, “you’re heading into the wild blue yonder.â€
Yet, even Marler recalled a thought-provoking study of white-crown sparrows: “We had a male who burbled a soft rendition of a particular song while going to sleep. Of course, you don’t know what was going on inside his head. But it was a song he sang to a specific female he had mated with five years earlier.â€
Was the sparrow reliving a happy liaison? It’s impossible to say, and that’s why some scientists remain skeptics.
Glen Stewart, a professor of zoology at Cal Poly Pomona and an expert herpetologist, draws a line on referring to tortoises, which have pea-sized brains, as studs and hussies.
“Kristin Berry is a solid scientist and one of the real authorities on desert tortoises,†Stewart said, carefully weighing his words. “But when it comes to reptiles, it may be a little inappropriate to use terms like hussy and so forth, and more appropriate to say things more objectively.â€
But Marc Bekoff, a proponent of animal personality at the University of Colorado, found that the motions and postures of canines at play are part of a complex social language.
“Evolutionarily, it makes sense to have diversity in personality,†Bekoff said. “And we clearly see that animals have distinct personalities, and their motivations to do different behaviors vary from day to day, moment to moment.â€
Added Bekoff: “You can’t have a wolf pack of all alpha males.â€
In the Mojave, tortoises display such a wide variety of personalities during courting season that it is hard to fully understand them. Yet, in the battle of the tanks vs. tortoises at Ft. Irwin, about 30 miles northwest of Baker, their survival depends largely upon whether scientists can discern what makes a tortoise tick.
The military plans to expand the area used for battlefield exercises to accommodate a new generation of weapons and tactics. Those plans include relocating about 1,500 of the reptiles, which are protected by state and federal law, to new environs where they won’t be squashed by military equipment.
In the largest relocation of reptiles ever attempted in California, the first wave of 300 tortoises is expected to be trucked out early next year to similar terrain several miles away.
“Social behavior is something we’re seriously looking into in our translocation plans,†said Mickey Quillman, natural and cultural resources manager at Ft. Irwin.
“We’ll be taking tortoises from the same general vicinity -- big ones and little ones -- and moving them together in one fell swoop,†he said. “Kristin Berry’s studies suggest there’s a good chance those tortoises have intermingled in the past, and we don’t want to break up that behavior.â€
Tires crunched on gravel as Berry stopped her truck and gazed across a designated Army tortoise research site of arroyos, alluvial plains and hills buttressed by the Soda Mountains.
On this arid stage, Berry has outfitted 28 tortoises slated for removal with radio transmitters in order to learn all she can about what she called “one of the few populations left in California that is remote, stable and relatively intact.â€
With a wave of her hand, Berry said, “From that ridge all the way over to that one, a magnificent 10-pound alpha male tortoise we know as No. 43 reigns supreme.â€
“He’s not good at mating -- too eager. He just looks at a female and turns to mush,†she said with a laugh. “But he’s a heck of a fighter and patrols a huge territory. We’ve seen him make long, arduous journeys across a wash and halfway up a mountain just to beat up a smaller male.â€
Berry trudged to the top of a hill and used a hand-held antenna to pinpoint the locations of other tortoises.
On that day, all the action was below the surface in burrows connected by dusty paths tortoises have used for perhaps hundreds of years.
Peering into one of the caves with light reflected off a small mirror, she said, “There’s a little guy in front and a big mama in back. It’s a big female who prefers boys to big alpha males.â€
Female tortoises are choosy about their mates.
Take tortoise No. 41, a very old, reclusive and small female with osteoporosis. She has four boyfriends, none of them among the alpha males who occasionally visit her.
Tortoises spend most of their lives underground.
But when mating season reaches its height -- August through early October -- they lumber forth in the mid-morning and late afternoon to forage for wildflowers, and display a suite of courting and dominance behaviors based on constant fighting.
When male tortoises face off, they bite, claw and ram, and use a horn under the chin to flip a foe over on its back.
Then, in a humiliating coup de grace, the winner mounts the loser.
Their aggression is not surprising. Male tortoises in mating season are operating under the influence of extremely high levels of testosterone.
In the afternoon, Berry caught up with a tortoise she officially knows as No. 29, and unofficially as the “cad†and “fearless kingpin.â€
He probably hatched from an egg when Calvin Coolidge was president. As the big male was weighed and measured by an assistant -- about 11 inches long and about 9 1/2 pounds -- she gazed into its eyes and said, “There is so much we still don’t know about these creatures.â€
“At a time when disease is spreading among them and there are plans for translocation, we’re only beginning to study their social lives,†she said. “Determining how complex these creatures actually are can help us understand better how to save them.â€
No. 29 stared back at her, eyes blinking.
