Ecology

Mammalian Carnivores of the Tom’s Creek Watershed

Lizzy Ryan
Strawberry Hill Nature Preserve

(1/2021) South Central Pennsylvania is home to its fair share of mammalian carnivores. A carnivore is an animal that eats meat. An herbivore is an animal that eats plant matter. Carnivores are extremely important in any ecosystem. They keep their environment balanced. I always come back to the Lion King. Mufasa says to Simba, "Everything you see exists together in a delicate balance. As king, you need to understand that balance and respect all the creatures, from the crawling ant to the leaping antelope." But Simba says, "But dad, don't we eat the antelope?" To which Mufasa replies, "Yes, Simba, but let me explain. When we die, our bodies become the grass, and the antelope eat the grass. And so we are all connected in the great Circle of Life."

Carnivores eat the herbivores. The herbivores eat the plant matter. If there are too many herbivores, vegetation becomes overly grazed. Without enough vegetation, there is little variety in plant and animal life, which in turn hurts the food chain.

One example that many like to use when speaking of predator/prey relationships in the environment is the wolves in Yellowstone. Wolve were once extirpated from Yellowstone. When this happened, the elk population skyrocketed. When the elk population rose, the number of shrubs and trees were reduced dramatically. The other animals that depended on that vegetation for food and shelter disappeared.

In 1995, Yellowstone began reintroducing wolves back into the park. Many were worried that this would disseminate the existing elk herds. Instead, the wolves actually enhanced the elk herds by preying on the weak and sick elk. The elk population stayed steady. It is survival of the fittest at its finest.

We don’t have any wolves around here, but we do have other carnivores. One carnivore similar to the grey wolf is the eastern coyote. "Recent research shows the eastern coyote is an immigrant, the origin of which likely involved interbreeding between coyotes and gray wolves. Analysis of DNA suggests coyote-wolf hybridization has occurred (Penna. Game Commission)."

In the 1960’s, it appears as though many coyotes came to Pennsylvania from the Catskill Mountains in New York. Over the years, their population spread across the state. Male coyotes weigh between 45-55 pounds and the females between 35-40 pounds. Mating usually occurs in the winter and pups are born in the spring. They normally have litters of 5-7 pups in their dens. Dens can be in hollowed trees or rock crevices. The young leave the mother at around 6 months of age. Sometimes coyotes will hunt in packs and other times they will hunt alone. Coyotes mainly eat rabbits, voles, moles, deer, groundhogs, and other smaller mammals.

Foxes are another common carnivore in Pennsylvania. We have two species of fox: the red and the grey. Foxes are in the dog family or canine (Canidae) - the same as coyotes and wolves. Both species of fox weigh between 7 and 14 pounds in adulthood. Both are mainly nocturnal. Grey foxes have the special ability to climb trees. They will eat anything they can catch- small rodents, chickens, groundhogs, opossums, rabbits, and birds. They will even eat carrion. Male foxes are called "dogs" and the females are called "vixens". Just like the coyotes, foxes will create or find dens to have their litters in. Dens can be hollow logs, crevices, and even burrows in the ground. Females have their young (average about 6 per litter) in the winter in these dens. The young stay with the mother until the fall where they then go off to establish their own territories.

Bears are our largest meat eater. However, their diet does not just consist of meat. Black bears are omnivores, that is, they eat both meat and vegetation. They love to eat wild berries and nuts as well as leaves, grasses, insects, amphibians, fish, carrion, and small mammals. Sometimes, adult black bears will prey on newborn white-tailed deer fawns during their first few days of life.

In the fall, the bears are active, foraging for food to fatten up for the winter ahead. They normally begin to hibernate in mid to late November with the pregnant females going down for their winter’s nap first. Bears will create dens in rock fissures or caves, a hollowed tree, or any other crevice they can find. Females will normally give birth in their den. While bears do sleep during the winter, they also will leave and defend their den.

Then there is the elusive bobcat. Bobcats are our only native feline predator. They weigh approximately 18-25 pounds in adulthood. Bobcats are colorblind and are mostly nocturnal. Like foxes, they will eat most anything they can catch - small rodents, birds, mink, muskrat, groundhog, squirrels, and rabbits. Occasionally, they will take young or sick deer as well. Breeding is in late winter. In the late spring, they typically have a litter of around 3 kittens in a den. In the early 1900s bobcats were considered varmint and even had a $15 bounty. "More than 7,000 bobcats were killed for bounty from 1916 to 1938; the majority of these were reported during the 1920s. A realization that bounties were ineffective for controlling predator populations resulted in the removal or reduction of bounties on many predators. The bounty was removed from bobcats in 1938, but they remained unprotected and were widely persecuted until classified as a furbearer in 1970 (The PA Game Commission)." Now, their population is expanding.

Weasels are long-bodied carnivores with short legs. There are 3 species of weasels in Pennsylvania. They are the short-tailed weasel, the long-tailed weasel, and the least weasel. They will eat a variety of different animals, but mostly on small rodents. They are quick and agile predators and are known to bite their prey right behind the skull. "Females give birth to 4-12 young in an underground nest (The PA Game Commission)."

Minks are another carnivorous mammal in the weasel or Mustelid (Mustelidae) family. They are semi-aquatic and weigh only 1-2 pounds. They have a very similar diet to the weasel and also kill their prey with a bite to the back of the skull. They prey on small rodents, crayfish, amphibians, chickens, snakes, birds, and fish. They tend to kill more than they eat and will stash extra food away for later. They create dens in old groundhog tunnels or hollow logs near water.

All species play an important role in an ecosystem. All the way from the tiniest insect to the largest predator; everything is connected.

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