Social Cats

Science pokes under the sofa, bats around a few ideas

The most common myth that people have about cats is that they’re solitary, asocial creatures, fumes Sharon L. Crowell-Davis, a behavioral veterinarian at the University of Georgia in Athens.

Groups of cats have colonized much of the planet from Rome’s Coliseum and Forum to Anywhereville’s town dump. But how do these groups work? Jill Engel-Cox

Supposed standoffishness hurts an animal’s image, says Crowell-Davis, and she diagnoses the perceived aloofness of Felis catus as the main contributor to outbursts of anticatism. Which species provided the devious villains in the recent movie Cats & Dogs, for example? Not the romping, barking pack. And don’t even get her started on the humor book that lists a hundred and one uses for a dead cat.

Crowell-Davis contends that even in the scientific community, stereotypes of cat asociality persist. In the literature, “I’ve read that because cats don’t form [a particular kind of] dominance hierarchy, that’s evidence of their nonsocial behavior,” she says. “And then I read that cats do form that hierarchy, and that’s evidence of their nonsocial nature.”

The simplest definition of a social species requires its members to form stable relationships, she explains, and several decades of fieldwork have documented them in cats, from the English dockyards to the Forum in Rome. Crowell-Davis, in fact, is convinced that “there’s a lot of politics in a cat colony.”

Interpreting social structures is only one of the fascinations of watching groups of cats. Other researchers are turning to domestic cats to answer questions about mating systems and the impact of hunting by clustered animals. Also, some scientists are tackling the question of whether Fluffy and Tiger’s endearing quirks represent an animal version of personality.

Updated classic

Showing that a species forms social groups takes a bit more than spotting two animals in the same place, cautions David MacDonald of Oxford University in England. He and two of his Oxford colleagues reviewed studies of cat sociality and published their conclusions in the 2000 update of the behavioral classic The Domestic Cat (2000, D. Turner and P. Bateson, eds., Cambridge University Press).

Analyses in the 1970s tended to treat clusters of cats as a bunch of asocial loners drawn to the same resource, MacDonald recalls. He led a study of three colonies of free-living cats, such as those hanging out around a farmer’s barn. The researchers kept track of which cats hunkered down within 5 meters of each other, a task that required 59,000 observations of several dozen cats.

“It became clear that the behavior of individuals in these colonies is far from socially random,” the investigators reported. “Cats choose to sit together, and each individual favors the company of some over others.”

Searching for what might influence the preference for neighbors, MacDonald and his colleagues checked for relatedness. Among adult females, a cat was more than four times as likely to sit near a female relative than a female from another lineage.

Early in the study, the researchers watched a pregnant female squeeze into a crevice between straw bales where her sister was raising three kittens. Amid those squirming kittens, the newcomer gave birth, and her sister acted as midwife. The attending sister licked the cat in labor, licked the newborns clean, and nursed them.

The two mothers continued to raise their litters jointly, nursing whatever mix of the kittens was hungriest at the moment and joining forces to fend off intruders. Once the researchers realized what they were looking at, they found communal kitten raising in the other colonies they studied.

One of Crowell-Davis’ students, Randall Wolfe, now at Georgetown (Ky.) College, hypothesized that gender controls these associations. He predicted that females would associate with their female relatives but not their male kin. For a pilot study, he staked out a Georgia dairy barn and kept track of which cats rested together. He found no gender pattern–a female was as likely to associate with a male as with another female. So much for his original idea.

“I kicked it around as people are wont to do when their hypothesis has been shot in the foot,” he recalls. Finally, he began to wonder if cats develop some version of buddies, regardless of gender. As Crowell-Davis explains it, “It’s as if they just like each other.”

To test this idea, Wolfe moved his stakeout to the land around a house locally renowned for its abundant cats. About 20 cats, most of them related, gathered around the house. All the cats had been neutered, so Wolfe hoped to see associations uncomplicated by mating interests.

Wolfe divided the area into a grid and spent his weekends jotting down which grid square a particular cat occupied and what other cats were nearby. “People have a preconception that cats spend most of their time asleep,” Wolfe says. “Actually, there was a lot to watch.”

Nevertheless, it didn’t always add up to high-action drama in the Georgia summer. “There were some times when it got a little old, usually at 2 o’clock in the afternoon, when it was getting hot and the cats were sleeping,” Wolfe says.

When Wolfe analyzed all the data at the end of his 16 weekends of observations, he found that the cats indeed had preferred associates. The cat buddies showed up together in a variety of locations. Wolfe again found no predominance of female-female associations or other clear gender patterns. He had only spotty genealogies for the animals, so he didn’t attempt an analysis for lineage.

What makes the domestic cat’s sociability especially interesting is its contrast to the rest of feline life, MacDonald comments. Most of the 39 or so species in the cat family live solitary lives. Genetic analysis during the late 1990s found that domestic cats belong to a lineage of six species of small, solitary creatures that probably arose around the Mediterranean.

There is nevertheless some sociability beyond the house cat. Male cheetahs hang around with their brothers, and female lions stay in matriarchal prides.

Sexual interest

Although Wolfe negated sexual interest among cats he observed, this factor formed the centerpiece for a study by Ludovic Say of Claude Bernard University in Lyon, France, and his coworkers. For 3 years, the team monitored cat receptivity and mating on the grounds of a local hospital.

In two of the years, all the females came into heat during the same 3 months, sometimes with as many as 10 females looking for mates on the same day. In the other year, their receptive phases stretched over about 5 months.

The researchers analyzed DNA from the 50 or so adult cats and nearly 160 kittens born during the study. Using the data to identify fathers, Say and his colleagues found that paternity patterns differed in the oddball year.

That year the males showed an unusual range in the number of kittens they sired. The most prolific fathered 13 kittens, followed by a father of 10, and then a string of scores right down to only 1 kitten.

Some adult males had no kittens. In all, the males showed five times the variation in fatherhood that year than in the other two years, the scientists reported in the May 22, 2001 Proceedings of the Royal Society of London.

That finding fits predictions about mating systems and male competition, they point out. In a dense group of animals, the top males have trouble monopolizing multiple females that are sexually receptive at the same time. Hence the first two years of observation, when males bunched together in their success and there were no big winners. Spread out female receptivity, however, and more of the males will show up and compete for each female in heat. In that scenario, a few tough cats dominate most of the encounters and so are likely to father more kittens than the other males do.

Divide and hunt

Just how cats divide the areas where they range and hunt has attracted attention from both conservationists and scientists. A 1980s survey of cats’ prey in the small village of Felmersham, England inspired alarm about how big a bite cats take out of local fauna. The average cat nabbed 14 prey during 1 year.

One of the more detailed follow-ups to the Felmersham study came from David Barrat, now of the Demersal Fisheries Program in Canberra, Australia. In the early 1990s, he put radio collars on suburban cats in Canberra to observe their prowling and hunting habits. With about half the cats in the study turning out to be yard potatoes, but the others venturing far afield, the mean range turned out to be some 7 hectares, or about 17 acres. In general, Barrat reports, the cats’ nocturnal ranges extend farther than their diurnal ones.

To see what the cats caught on their nightly rounds, Barrat recruited owners of 214 cats to save dead animals that their cats brought home. In a year’s monitoring, ending in the spring of 1994, the researchers found that most cats nailed and carried back only about 10 creatures, but a small proportion of the study cats showed up with at least an animal a week. Some 65 percent of the total haul consisted of house mice, black rats, and other small mammals. However, the cats proved superb opportunists at hunting, pouncing on frogs, various reptiles, goldfish, and representatives of 47 bird species.

Conservationists have proposed that people keep their cats indoors at night. That restriction might offer protection to many small nocturnal mammals, but it wouldn’t save daytime birds, says Barrat.

Bells on cats’ collars don’t seem to work, Barrat reports. Belled cats caught no less prey than bell-free hunters did.

Andrew Rowan, research director for the Washington, D.C.-based Humane Society of the United States hesitates to commit on the perils of felines in most neighborhoods. “The debate is far from settled,” he grumbles. Nevertheless, he notes the danger of letting cats loose on islands where native creatures have never confronted them before.

Indoor ranges

Not much research has clarified cats’ use of space inside people’s homes, says Penny L. Bernstein of Kent State University’s Stark campus in Canton, Ohio. She and Mickie Strack, now at Stockton State College in Pomona, N.J., started by monitoring which of Strack’s 14 cats hung out together in the 1,600-square-foot house she lived in at the time.

Bernstein and Strack identified an indoor version of ranges, overlapping but individually distinct, within the house. The oldest male, Julius, roamed throughout the house, whereas a female named Lily spent her time in the most constricted range, venturing off the top of the refrigerator only rarely and briefly.

Many of the cats favored the same spots, such as a sun-drenched chair, in their overlapping ranges. “They time-shared,” Bernstein reports. One would get the good location for a while, but then somebody else would move in.

All these arrangements were negotiated with very little fighting, just hissing and an occasional swat. Yet the cats Bernstein and Strack watched were living at 50 times the density reported for colonies of outdoor cats.

Bernstein describes the dominance arrangements among cats as more fluid than those of dogs or primates, and the ways of working these out as far more subtle. Julius, the cat with the largest range in the researchers’ observations, died during the course of the study. After his departure, the other cats’ activity patterns shifted. Lily started coming down from the top of the refrigerator much more often. Yet she and Julius had hardly seemed to interact.

Early social skills

Just how do cats develop their social skills? Earlier observers noticed that both puppies and kittens pass through a sensitive period for becoming socialized to people and other animals. Dogs learn about the society of their world between the ages of 8 weeks and 6 months.

“Exposure much earlier than that doesn’t seem to stick,” explains John W.S. Bradshaw of the University of Southampton in England. Kittens form many of their social habits earlier, starting around 2 weeks after birth and continuing for only about 2 months, he says.

A series of old experiments tested the limits of manipulating kittens, socially and otherwise, by arranging weird early experiences. In 1930, pioneering psychologist Zing Yang Kuo reported that kittens raised in the same cages with rats never killed rats of the same strain they grew up with. Kittens raised with both rats and other kittens preferred the feline company but grew into adults with less-than-usual tendencies to kill rats.

However, Bradshaw points out, cats “are complex animals.” A kitten that lags in some ability may find a shortcut to catch up. Testing kittens for some of the basics of predatory skills at 3 months didn’t necessarily predict how they’d score at 6 months, according to studies in the late 1970s. Kuo reported that even a cat that had reached adulthood by the time it had its first opportunity to kill a rodent improved significantly after just one try.

Cats differ so much in their sociability, as well as in other qualities, that Bradshaw has started looking for a feline version of personality. The term he uses, however, is behavioral style.

The idea that animals might have their own versions of individual personalities crosscuts decades of scientific tradition, Bradshaw admits. Biologists striving for objectivity traditionally permitted themselves only to note the easily measurable qualities of an animal.

Such practices conjure a world where all 2-year-old neutered female cats are alike.

“That strikes me as being somewhat perverse,” says Bradshaw. Biologists base so much of their work on evolution, he explains, “yet evolution only works if there’s variation.”

Figuring out how to talk about those individual quirks and characteristics that make up a behavioral style in an animal isn’t easy. Researchers searching for stable, basic qualities have proposed behavior measurements for such animals as fruit flies, yellow-bellied marmots, and pumpkinseed sunfish.

Bradshaw and his Southampton colleague Sarah Lowe have approached the issue of cat personalities through detailed observations of nine litters of kittens at 4, 12, and 24 months of age. Lowe made all her observations just after the kittens had eaten-her effort to bring some kind of standardization to feline behavior.

A cat’s tendencies toward or against four kinds of behaviors held relatively constant throughout the period, Bradshaw and Lowe reported in the January Animal Behaviour. They described these building blocks of behavioral style as inclinations for staying indoors; rubbing against a chair leg, human leg, or other target; investigating oddities such as a visitor standing around taking notes; and more generally acting boldly rather than shyly.

The thread of the work fits studies of other creatures in which individuals tend toward relatively consistent degrees of shyness or boldness.

Mere humans have a tough time analyzing feline behavior. A certain scent or a subtle pose seems to carry volumes of meaning for cats, but people just don’t get it. Crowell-Davis says that it’s not fair to assume that what’s hidden from people isn’t there.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.

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