How Predators Establish Home Ranges and Territories 

When wolves, cougars, bobcats, bears and many other wild predators become adults they roam rather distinct areas where they seek food, cover, and mates. The often painful process of “leaving the nest” and occupying a territory is well known to us. It inspired Disney’s The Lion King and many other movies, documentaries, books and articles. It’s something people can relate to, although (as comedian Bill Cosby said) kids leave home a lot later and come back more often than they used to.

While most people are generally familiar with the concept, they don’t know much about the details of home range establishment by predators. Michigan’s big carnivores exhibit great variation in selecting home ranges. Typical home range sizes vary from around 250 square miles for an Upper Peninsula wolf pack of four or five animals to only 8 to10 square miles for a female black bear. For solitary species like cougars, bobcats and bears, the home ranges of males are considerably larger than for females.

Within a given species, food abundance plays an important role in determining home range size. Wolf pack territories are much smaller where deer are plentiful than in areas where prey is scarce. Home ranges may vary in size from year to year, as food supplies expand or shrink. But some predators won’t necessarily leave an established home range for “greener pastures” when facing prey shortages. For example, cougars have been known to stay put even when deer move out of the cougar’s home range. This is an evolved behavior that adapts cougars to persist in low numbers even if prey is scarce.

Territories are defended areas (within home ranges) that may be much smaller than the animal’s entire home range. It is a myth that battles over territory are almost always non-fatal “shows of strength.” That notion makes territorial battles more palatable to film watchers. But in fact, fighting and even cannibalism are major causes of mortality in cougars and other large predators. Biologists sometimes refer to the demise of young cougars that venture into the territory of a dominant male as “getting crunched” because the loser’s skull is often crushed. People sometimes catch raccoons and other predators and release them somewhere else. They assume the raccoons already occupying the release area will just move over and give the newcomer a chance to survive. But more often the released animal runs into trouble as it invades established territories.

Curiously, wolves with territories sometimes tolerate newcomers. And sometimes they don’t. The newcomer may be allowed to cross the pack’s territory or even join the pack. But more often wanderers will be driven off or killed. In cougars, territories of males don’t overlap much, whereas a dominant male’s territory may overlap that of several adult females. A young female cougar establishes a territory that overlaps those of one or more other females, often including its mother. This tendency is called philopatric behavior. This means female cougars typically don’t wander off very far from where they were born, whereas males may go long distances until they find a home range with no dominant male. Philopatric behavior is not exhibited strongly in certain other large predators such as wolves. Females will sometimes disperse long distances from their birthplace.

Territories are well-marked by males of many species. Bobcats and cougars make scrapes, by scratching out depressions in the ground much like a white-tailed deer. These scrapes are scent-marked and scats are sometimes deposited in the scrape. Cats may also scent mark trees, shrubs or other objects.

Border disputes occur despite such warnings. Wolf packs occupying adjacent territories often have a narrow land of overlap, perhaps a mile wide. The wolves are stimulated to remark their boundaries whenever they smell invaders of this “zone.” These overlap areas are usually along ridges, rivers, or other easily-followed edges.

Wolves and coyotes also stake claims to territories through howling, barking and many other sounds. The howling of wolves has been studied by humans for centuries, but there are more guesses than proven facts with regard to the exact meaning of different howls. We do know that howling lets other packs know the exact location of the wolves sounding off, and probably lets the listeners assess the relative strength of the howling pack. Thus, it is an indirect means of territorial defense.

There are many exceptions to the “standard” behavior of particular species. Some evidence suggests that cougars will occasionally abandon home ranges and set-up temporary home ranges, then eventually return to their original areas. And not all wolves are territorial. The wolves of the tundra that follow caribou herds over thousands of miles don’t seem to have territories except perhaps when denning with pups. The caribou they follow take different migratory routes each year so there’s really no definable area to defend.

Most predators have maternal dens for raising young, but do not have permanent homes. Television shows and movies often have bears returning day after day to the same cave, but that doesn’t happen much outside of Hollywood. Predators move around a lot within the home range and use a variety of cover, crevices, or holes in winter to sleep or avoid bad weather.

Biology classes often emphasize that when prey increases, predator numbers go up, and when prey is scarce the predator population decreases. That’s generally true, but this so-called balance of nature is complicated by important social factors. Wolves may cause declines in prey and still become over-abundant. Conversely, pack disruption, disease or genetic problems may prevent wolves from increasing where prey is abundant. Territoriality limits the number of predators that can occupy a certain area, and social interactions, genetics and disease regulate predator births.

Dr. Patrick J. Rusz
Director of Wildlife Programs

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