My pet peeve
According to Konrad Lorenz, a baby jackdaw has no idea who its enemies are and is willing to be friends with such undesirables as a fox or a cat. The one exception to this tolerance is a creature gripping anything resembling a jackdaw. “Any living being that carries a black thing, dangling or fluttering, becomes the object of a furious onslaught.” Lorenz’s hand-raised baby jackdaw would attack him if he picked up the other jackdaw in the nest. Lorenz was attacked by a flock who spotted him carrying a wet black bathing suit, and he saw jackdaws attack another jackdaw who made the mistake of trying to carry a raven’s feather to her nest.
Birds and ground squirrels are the best-studied mobbers, but not the only ones. Three humpbacked dolphins mobbed a shark on the South African coast, repeatedly chasing it and driving it into coves until it took off for the open sea. Fish mobbing has been seen in which damselfishes, butterfly fishes, and surgeonfishes, alone or in gangs, approach a moray eel or a lizardfish with harassment on their minds.
Mobbing sometimes works wonders. Jon Rood saw a martial eagle swoop down and grab a banded mongoose out of a pack foraging in the Serengeti. The eagle, flapping low, landed in a nearby acacia. As it did, the other 13 mongooses raced for the tree. Several climbed the tree and the dominant male, the oldest mongoose, swarmed up to the branch where the eagle sat, lunged at it, and startled it into dropping its prey, which it had not yet killed. For the next seven minutes, mongooses boiled around the base of the tree and the lower part of the trunk, and then they all ran off together, including the rescued animal, who was limping slightly.
Let’s go see what all the screaming is about
Mobbing provides clues to a naive young animal as to who should be regarded with concern. Another behavior that provides such clues is inspection. Wildlife observers are sometimes surprised when they notice that prey species don’t always flee at the sight of predators and acts of predation, and may wander over for a hard stare.
Thomson’s gazelles inspect many predators. They put in more time inspecting stalking predators like cheetahs and lions than coursing predators like wild dogs and hyenas. Clare FitzGibbon analyzed 90 cases of gazelles inspecting cheetahs. Gazelles who spot a cheetah are apt to walk over and look at it. The whole gang often comes along to mill around gawking. If the cheetah walks away, they follow, sometimes for over an hour. Up to a thousand gazelles have been seen following a cheetah. And some of them were snorting. This makes it hard for a cheetah to sneak up on its prey.
Gazelle children and teenagers were the most likely to approach and inspect cheetahs. Adults were the next most frequent inspectors. Fawns did not inspect cheetahs at all: either their mothers led them away or the fawn lay down with its head flattened to the ground, literally keeping a low profile. Inspecting is not risk-free. FitzGibbon saw one adult and two half-grown gazelles attacked and killed from groups of gazelles following cheetahs.
Cheetahs moved away farther and faster when gazelles inspected them than when they were left alone. The more gazelles, the farther away the cheetahs went. The gazelles may also be gaining information about cheetahs—what they look like, how they move, what they smell like, and so forth. “The fact that younger gazelles were more likely to approach than older animals suggests that they may be using the opportunity to learn more about the predators,” FitzGibbon writes.
In the Serengeti, George Schaller saw buffalo inspecting crime scenes where buffalo had been killed by lions. They came in such numbers that they drove the lions away. Thus, he saw five male lions kill a buffalo in the late morning, and when he returned in the early evening, 100 buffalo were there, milling around and sniffing the ground while the lions stood back and waited. The habit of prey animals of staring at the sight of predators eating one of their number is sometimes called the bystander phenomenon. A buffalo bystander would surely learn that lions are to be distrusted and that the stakes are high.
Kobie Krüger describes walking in the South African bush with her dog Wolfie and Leo, a tame teenaged lion, and seeing the reaction of the waterbuck, wildebeest, kudu, and impala, who would stop and stare at this inexplicable combination. One male waterbuck seemed particularly perplexed and would often drift over to stare at the three, occasionally stamping a hoof “as if demanding an explanation.” Krüger liked to throw her arms around the dog and the lion just to boggle the waterbuck further.
Even minnows seek information about pike. Pike are large predatory fish that eat minnows. When a pike is put in a tank with a school of minnows, the smaller fish at first huddle together. After a little while one or a few minnows will sally forth and examine the pike, staying away from its mouth. The interactions of minnows and pike have been intensively studied, perhaps because it is so hard to keep lions and buffalo in the laboratory. What makes it worthwhile to engage in such risky actions?
After inspecting a pike, minnows return to the safety of the school. This is real safety, since it is harder for a predator to pick a fish out of a school than it is to grab an isolated fish. Sometimes the inspecting fish returns with a skitter that may convey information to the other minnows. If inspection only carried risk and no benefit, the genes of minnows who indulged in it would all be eaten by pike. Hypotheses about possible benefits include not only getting information about the pike—whether it really is a pike, and if so, how hungry it is—but also providing information about the pike to the other fish. If the rest of the school knows how dangerous the pike is at this moment, the school can act accordingly, and each fish benefits if the school acts appropriately. Being approached may discourage the pike by letting it know it has been seen. It has also been suggested that female minnows may be favorably impressed by the boldness of males who inspect predators, and more inclined to mate with them.
Enemies? I have enemies?
Wildlife rehabilitators often need to teach animals raised in captivity how to spot a predator and what to do if they spot one. This comes more easily to some animals than others. Species that have lived for millennia without predators—on islands, for example—may be much too trusting.
Researchers Andrea Griffin, Daniel Blumstein, and Christopher Evans worked with tammar wallabies from an island population where there were no predatory mammals. They thus hadn’t seen predators in 9,500 years.
The researchers set out to make wallabies fear foxes. Seeing a model fox while wallaby alarm thumps were heard did not trouble the wallabies. What did trouble them was being caught in a net. “Approaching humans consistently elicit alarm response in captive marsupials, probably because animals associate them with being caught, bagged and handled.” They decided to pair the sight of the fox model with that of a human carrying a net. The model was a stuffed fox on a wheeled cart, moved by a string and pulley system. The fox model would roll out and within seconds a human with a net would fake trying to capture the wallaby. The fox rolled back and forth, the human pursued the wallaby back and forth, and then human and fox exited.
Wallabies subjected to this training were noticeably less calm about the fox model afterward, and when a cat model was produced, they didn’t like that either. A stuffed goat didn’t bother them. It was considered encouraging that the wallabies held their bad fox experiences against cats, suggesting that they have a generalized concept of “predator” that can be triggered.
Another group of Australian researchers trying to make quokkas and rufous bettongs (two species of small marsupials) fear foxes didn’t have much luck with a stuffed fox (and a different protocol), but a series of experiences with a very sweet dog were so hideously misunderstood that afterward quokkas and bettongs viewed both dogs and foxes with the greatest alarm. The large white dog was trained to chase but not harm animals. She was careful not to crash into them, and if she cornered one, she licked it. Neither quokkas nor bettongs appreciated what a great dog this was, and furthermore, foxes reminded them of the dog.
Everywhere, foxes
Wildlife biologists reintroducing captive-raised houbara bustards
(think: turkeys of the desert) in Saudi Arabia found that more than half of the young birds didn’t make it through the first year, being gobbled up by predators, particularly red foxes. Most bustards perished within three weeks. One group was “trained” with a mobile fox model intended to make them fear foxes. Instead of learning “foxes are scary, avoid them” the bustards habituated, learning “our friend the mobile fox model won’t hurt us, relax.”
The bustards did not instinctively regard foxes as scary. The first time they saw the model fox they were a bit upset, but no more so than the first time they saw a model penguin. (Where you get a penguin model in the middle of Saudi Arabia is not explained in the articles I have read. Scientists are resourceful people.) Training with the model fox didn’t reduce bustard mortality.
Since the fake fox didn’t work, the researchers got Sophie, whose “delightful personality threatened to shift our allegiance from bustards to foxes.” When she was old enough, bustards were treated to “encounters with a live red fox, muzzled and on a long lead.” These meetings took place at dusk, in a cage with two wild bustards “to provide examples of appropriate fear responses.” Tapes of bustard alarm calls were played. This haunted-house program worked well—foxes now freaked the bustards out.
Subsequent data showed that bustards who had been exposed to Sophie before release were much more apt to survive than bustards who had merely seen a fox model. The actual fox made deadly serious attempts to catch and kill the bustards, and the bustards seem to have noted the vibes. Although Sophie was muzzled, she several times managed to slip the muzzle and seize a bustard, although she never got to keep or kill it. Sophie did get to participate in the release of the bustards by chasing them out of their cages.
Dingo puppies in central Australia aspired to catch rabbits but had terrible technique. Their running was floppy and awkward. They lacked stealth. To see a rabbit was to hurtle toward the rabbit, and the result was that the rabbit, easily spotting the puppy, scooted down a burrow. Not in great terror, and not until the last moment, since “the rabbits seemed to know that the pups were only amateur hunters,” according to researcher Laurie Corbett. As the season progressed, the pups got slyer and the rabbits got jumpier. The pups stalked from cover and didn’t make a dash until they were close, and they now ran smoothly. By this time the merest glimpse of a dingo was enough to make the rabbits dive for a hole.
Wild black-footed ferret kits are wary when they first stick their noses above ground. But captive-reared ferrets may be all too bold and lollop around on top of the earth as if there were no such things as eagles, coyotes, and badgers. Researchers sought ways to make the incredibly endangered animals more cautious. Rather than practice on actual black-footed ferrets, they worked with related Siberian ferrets.
In initial work, they used model predators. The model terrestrial predator was a stuffed badger mounted on a remote-controlled model truck frame, later famed as RoboBadger. The ferrets would be chased by a model, which they could escape by darting down a burrow. A photograph of a Siberian ferret being chased by RoboBadger shows a ferret that is running, but does not seem terrorized. And although the ferrets acquired a dislike of the models, a dislike that the scientists tried to enhance by snapping rubber bands at them while they were being chased, they got over it within a week.*
In subsequent work, they used a dog, a soft-mouthed retriever that would never hurt a ferret. A photograph shows a very happy dog chasing a very unhappy ferret, its mouth wide with horror. This experience proved somewhat more memorable than the model predators.
What, us worry?
Moose mothers are vigilant on behalf of their children and are particularly perturbed by the sound, scent, or sight of wolves and grizzly bears. If they have any idea what those are. In the Grand Teton National Park, where both predators have been gone for 50 to 75 years, mother moose scarcely reacted to the sound of wolf howls played for them. They went on eating. Weird sound—try the grass over here. When researcher Joel Berger sneaked up and tossed either snowballs soaked with wolf urine or grizzly bear scat wrapped in biodegradable toilet paper to within a few meters of mother moose, they weren’t bothered by the wolf smell. Sometimes they strolled over for a sniff. The bear smell worried them, suggesting that they may have some innate ability to recognize grizzly bears. (Or perhaps the smell reminded them of black bears.)
Moose mothers in Alaska, where wolves and grizzlies are an ongoing issue, reacted differently. Not only did wolf howls upset them, so did raven calls. Moose who are “predator-savvy” are likely to associate ravens with carcasses, and carcasses with predators. When Berger lobbed his scent bombs their way, both scents troubled them strongly. (Berger did some of his research dressed as a cow moose so that he could approach moose without alarming them. This is probably not as much fun as it sounds.) They lowered their heads, retracted their ears, and their hackles stood on end.
This is the kind of danger that animals learn about fast. The area around Jackson Hole has recently been recolonized by wolves. The wolves went through the naive moose population like hot knives through butter. But the moose responded. Mother moose who had lost a calf to wolves were 500 percent more responsive to playbacks of wolf howls, spending much more time scanning their surroundings after they heard howls. It wasn’t just that they were more sensitive because they had lost a calf, because mothers who had a calf hit by a car didn’t increase their vigilance to howls.
Competitors
In this world it is also possible to meet individuals who wish you ill, without actually wanting to eat you. Maybe they want to move into your apartment, maybe they want to break up your marriage, or maybe they just want to eat your lunch. It’s possible to learn who these vile individuals are. The Pacific gregory damselfish dwells on coral reefs, where it mostly eats algae. It defends its territory against other damselfish, against other algae-eaters, and, when it has eggs, against fish that might eat damselfish eggs. Biologist George Losey found that in the lab they generally left “predatory, bass-like fishes” alone, including a species it would not encounter in nature, the African tilapia, but that after a couple of weeks of watching tilapia gorge on algae, damselfish became testy. Losey tested this by training some tilapia to eat algae growing on bricks, and some to eat zooplankton from a dispenser. Damselfish housed with plankton-eating tilapia remained calm at the sight of them. Damselfish housed with algae-eating tilapia became increasingly hostile.
In a tank in the laboratory of John Todd, some small bullhead catfish were swimming about when a large bullhead catfish leaped in from a neighboring tank and attacked the little fish fiercely, mauling them so ruthlessly that all but two of them jumped out, fell on the floor, and died before help came. The big catfish was removed, and the two survivors began life anew. They established territories at opposite ends of the tank, which they patrolled vigilantly, and which they did not leave. Then Todd and his coworkers poured in some water from the aquarium of the big catfish, the Terror of the Tanks. Smelling the monster, the two little catfish fled their territories and huddled together, hiding until the scent had dissipated.
Listing your friends
It’s also good to recognize friends. For many baby animals, there are critical periods during which it learns who friends and family are. When that period is over, the animal is much less likely to accept new individuals into its life. Human parents see this when an infant who was happy to be held by anyone and everyone suddenly becomes insultingly particular and wails if it’s not in the arms of one of a very few people.
When David Macdonald’s fox cub, Niff, was 10 weeks old, she abruptly lost her unquestioning friendliness to newcomers. Till then, she had loved everyone she met. Now she only trusted the ones she already knew, and was terrified by new people. If a stranger dropped by, Niff would frantically scrabble up the chimney.
The human being—friend, foe, snack?
A mother polar bear became alarmed when her year-old cub displayed interest in a Tundra Buggy, an armored vehicl
e containing humans. He walked up to the buggy, and when his mother tried to push him away, he wouldn’t go. She walked away, then stopped, turned, and sat up on her haunches. She waved her paws and moaned. He gave in and went with her, and she led him a little farther away and nursed him before the two took off. She was letting him know that she viewed humans as a menace, a view it would be nice if all polar bears shared.
When the famous lion Elsa, subject of the book Born Free, had cubs, she wanted them to be part of her family, which included George and Joy Adamson. But by the time she introduced them, the cubs were old enough to be suspicious of humans. One day when the Adamsons had delivered a nourishing goat to the family, one of the cubs, Jespah, became annoyed at the sight of Joy Adamson handling their food and charged her. Elsa stepped between the two and whapped Jespah with her paw. Then she ostentatiously sat with Adamson in the Adamsons’ tent, giving Jespah the cold shoulder.
Making sure animals think of humans in the right way is a perennial problem for those who rehabilitate wild animals. Biologist Anne Collet describes the behavior of an orphaned seal pup who was rescued and lovingly restored to perfect health by marine biologists and released into the sea off the coast of France. A week later, not having gotten the meals she was accustomed to being served, the pup swam onto the beach, spotted a human, flopped up to him, and fixed him with her big brown eyes, ready to accept food. He walked away. She followed. He kept walking, she kept following. He went to a phone to summon help and she sobbed so loudly outside the door that he felt compelled to let her in the phone booth.
The marine biologists came. Realizing their mistake, they now made a point of acting like jerks, until the little seal grew to dislike humans. “You can’t believe how hard it is to be disagreeable to a young seal!” writes Collet. Subsequent baby seals had to be fed from hiding, chased, and generally treated in a cold, unloving manner so they wouldn’t get too fond of our kind.
Becoming a Tiger: The Education of an Animal Child Page 24