Hunsaker concedes that the question of intelligence can be a thorny one. When one researcher in the early 1950s devised a way of comparing the ability of various animals to negotiate a maze with that of human subjects, he found that Virginia opossums scored 58.9 percent as well as the humans did, compared with 47.5 percent for pigs and 45.3 percent for dogs (the two next most successful animals). Hunsaker thinks this is understandable in the context of the opossum's nomadic natural behavior.
In other research situations, opossums have demonstrated extraordinary obtuseness. One researcher found, for example, that in 300 trials of shocking opossums' forelegs, the animals never learned to move their limbs to avoid the unpleasant stimulus nor, in a separate experiment, did they ever learn to run away as a way of avoiding shocks. Unlike the higher vertebrates with their bigger brains, which can figure out appropriate responses to threats, "With these things, everything is: Open your mouth, hiss at it, and if it's too close, bite it. Otherwise run, and if you can't run, then you sometimes just fall over and play dead."
"Death-feigning" is rare among opossums, Hunsaker adds; he believes it's a response that occurs when the animal's nervous system gets overloaded. Paradoxically, when scientists record the brain waves and heart patterns of death-feigning opossums, they've been almost indistinguishable from those of normal, active animals. Even weirder is the fact that death-feigning Virginia opossums always assume the same pose: eyes open, mouths open and drooling, bodies positioned on their sides with the tail curling up between the legs. Hunsaker has written, "It appears that the animal has definite opinions as to what a dead opossum is supposed to look like, and will assume these positions if changed by an investigator." If the researcher closes the animal's eyes, the "dead" opossum will open them. If it's shifted into a position where its tail is straight and belly is on the ground, it will roll back onto its side and recurve its tail.
What explains this? "That's one of those mysteries of animals that make things so fascinating to me," Hunsaker says. He doesn't think anyone has solved it, and it may well be that no one is trying. Most biological research funds today are going into biochemical investigations. "If I were in charge of distributing money and I was really objective about it, would I want to throw $500,000 into a study [of opossum death-feigning] instead of a cancer cure, or work on an endangered species or a national park creation or something like that?"
Endangered species also tend to attract research money, but the Virginia opossum isn't endangered or even threatened. It's faring so well that you might think no one would care if local opossum babies were being left to die in the street because their mothers had been struck by cars or attacked by dogs. But the volunteers for Project Wildlife would prove you wrong. Since Hunsaker and his students stopped studying opossums, it's these volunteers who know more about the animals than anyone else in San Diego County.
Of all the local opossum-rescuers, it's hard to find one more knowledgeable than April Bauer. A relaxed, efficient woman who lives with her husband in an immaculate house in a semirural section of Vista, she found herself with spare time on her hands ten years ago. When she saw a brief television report about Project Wildlife, she volunteered at the organization's animal-care center near the foot of Linda Vista Road in San Diego. At first she cleaned cages and fed baby birds, but she soon joined the opossum team and began to care for local marsupials in her home. She thought the exposure to animals would be good for her two 12-year-old twin sons. "But they lost interest after a year," she says. "I stuck with it."
That's an understatement. About three years ago, Bauer became the head of the opossum team. As such, she directs the efforts of roughly two dozen volunteers while caring for up to 200 opossums a year herself. All together the team aids between 850 to 1200 opossums annually, one of the largest such efforts in the country. "We have a real high survival rate," Bauer boasts. "They do very well. They've been around for a long time."
Bauer says opossums will eat just about anything -- mice, rats, snails, slugs, insects, and dog and cat food, not to mention fruits and vegetables. But before the winter rains begin, Bauer points out, "the pickings are slim." From October through December, the opossums rescued by Project Wildlife tend to be starving and anemic and loaded with fleas. "They look gnarly. The fleas suck them dry and chew up all their hair." Some animals die from the infestations.
As winter progresses and baby mice are born and the rains boost the snail population, opossums fare better. Males move around more, looking for mates. But some are injured, like the two animals caged in Bauer's back yard when I visited her in early January. The older, a mature male, had been shot in the head with a pellet gun. A veterinarian had extracted one of the pellets, but five remained lodged in the animal's skull. "Hello, honey," Bauer crooned to a dark form curled up and sleeping on a shelf at the back of the enclosure. "C'mon, sweetheart. Turn around." The furry form stirred, then swiveled its head around to stare at us. "Possums are so mellow," Bauer murmured.
A moment later the gunshot victim bared his teeth at us. "See, now he's mad." Bauer sounded delighted. The animal would need to rely on its defensive instincts to survive in the wild. Bauer pointed out that the opossum's lip drooped, a sign of nerve damage suffered as a result of his injury. That and a lack of aggressiveness had made some of her fellow rescuers doubt it would be possible to turn this animal loose. If he couldn't be released, he would have to be euthanized, since state law prohibits individuals from owning wild animals. But Bauer was hopeful about avoiding that grim alternative. As if to confirm her optimism, the animal started trembling. "See, he's getting nervous. That's good." Another positive sign was that "at night he seems fearful of me. He wants out. He's been pacing. And he's been eating well. Mostly he eats kibble, but also chicken wings, and some avocadoes and vegetables. I left him a mouse last night."