Saturday, July 20, 2024

A red fox pauses in Lincoln in February 2022. (Photo: Richard George)

The red fox (Vulpes vulpes) is the most common fox species in Massachusetts. These foxes are smaller and lighter than most people realize. Your house cat might weigh more than a red fox, as these canines weigh only 6 to 15 pounds. The bones of a red fox are 30 percent lighter in weight than comparable bones in a dog. And the long, rust-colored fur of these foxes makes them look larger than they really are. Because they are so lightweight, these foxes are very agile and can easily jump over a 6-foot fence.

As the name implies, red foxes are usually reddish. They have black legs and a white-tipped bushy tail. The white-tipped tail makes it easy to distinguish these canines from gray foxes and coyotes. Red foxes have catlike and doglike traits: Like a cat, they hunt alone, often at night, have good night vision – and, like cats have a slitlike pupil; like dogs, foxes are good swimmers and have a large repertoire of sounds, including screeches, barks, yips, howls and whines. 

A red fox lopes along in Dennis on Sept. 26. (Photo: David Griswold)

Humans have hunted foxes since antiquity, and human-caused deaths are, even today, among the highest causes of fox mortality. Although fox hunting is legal in Massachusetts under certain conditions, the state banned the use of leg-hold traps in 1975. Despite this law, you may recall that two red foxes were caught in leg-hold traps in Arlington in September. One fox chewed off its paw to escape. It is not known what happened to it. 

The other fox was captured. Rehabilitators at Newhouse Wildlife Rescue in Chelmsford removed the trap, but doctors had to amputate the 7-month-old fox’s foreleg because blood flow never returned. Many rescue organizations euthanize three-legged foxes because it is thought they cannot survive in the wild. The rehabilitators at Newhouse Rescue decided to test this idea. They put the three-legged fox, now named Phoenix, through a series of tests and determined it could climb, jump, dig and capture rodents to eat. The rehabilitators released the fox in October. Newhouse Rescue has put up a $5,000 reward for the identity of the person who set these traps.

A sitting red fox on the South Shore on Oct. 23. (Photo: Karl Niemi)

Red foxes eat primarily rodents, but they will also eat rabbits, squirrels, eggs, frogs, insects, fruit and dead animals. If the prey weighs less than 8 pounds, a red fox might hunt it. When hunting is good, foxes bury excess food to eat later.

Foxes do not hibernate. In fact, they mate and prepare for pups during January and February. The female digs a 15- to 20-foot den, often in the side of a hill, in which to raise the pups. In about two months, the female gives birth to three to six pups. The mother nurses the pups for several weeks, then regurgitates food for them. Later, she brings the pups live prey that they learn to capture and eat. Both parents help raise the youngsters. At birth, the pups cannot hear or see because their ear canals and eyes are closed. That changes within two weeks; after about a month, the pups venture outside the den. By midsummer they can catch their own food, but they return to the den to sleep.

A red fox peers through branches in Lincoln on Feb. 12, 2022. (Photo: Richard George)

Those vertically slit pupils, unusual in canines, close more tightly than round pupils and allow the fox to better regulate the amount of light entering the eye. This helps foxes hunt under a wide variety of light conditions, from darkness to daylight. (Squirrels, on the other hand, are almost blind at night and are active only during daylight hours.) Foxes also have a layer of reflective cells at the back of the retina that reflect light back into the eye. This improves vision in low-light situations. Animals with this reflective eye layer produce green, yellow or blue eyeshine in night photos. (Human eyes do not have this reflective layer. When light is shined into human eyes, the light reflects back from blood vessels in the retina, creating red-eye in photos.) 

Foxes can see some colors in bright light, but they are red-green colorblind. A fox’s vision is most adapted for twilight and night activity. They can see in low-light conditions much better than humans. When red foxes hunt rodents they exhibit a behavior called mousing. The fox stands still listening and watching for the mouse. Then the fox jumps high in the air and brings its forelimbs down to pin the prey, steering with its tail. 

A pair of cautious red foxes on the South Shore on Oct. 23. (Photo: Karl Niemi)

Scientists have discovered that when a fox can see its prey, it pounces from any direction. But when a fox cannot see its prey (in tall grass or snow, for example), it pounces facing northeast, 20 degrees off from magnetic north. It is thought that foxes use their sense of hearing and the earth’s magnetic field to determine the distance to prey when they pounce without visual cues. The earth’s magnetic field tilts downward about 60 degrees below horizontal. As a fox creeps forward, listening for a mouse, it searches for the point at which the angle of the sound intersects the slope of the magnetic field. At that point, the fox is a fixed distance from the mouse, and it knows how far to pounce. Foxes are the only mammal known to do this.

Hearing is a fox’s most important sense. Foxes can move their ears independently of each other, allowing them to pinpoint the direction of a sound. (The right ear rotates clockwise and the left counterclockwise). A red fox can hear a mouse squeak 100 feet away and will dig through dirt or snow to catch it.

A red fox seen in October. (Photo: Karl Niemi)

Unlike dogs and cats, foxes have fur between their paw pads. These hairs provide detailed information about objects the fox touches. The hairs also detect air movement of prey. Foxes have long whiskers on their muzzles and forelegs. These whiskers provide the fox with information that helps map its surroundings. The fox maneuvers its whiskers around captured prey to know where to bite. The whiskers stick out the length of the fox’s body, so it can feel whether it will fit through a gap.

Foxes prefer to be left alone and will avoid people when possible. They most often hunt just before sunrise and just after sunset when people are not around. They sometimes den under a porch or shed. If this happens in your yard, if possible, leave the fox family in peace. Red foxes use dens only when raising their young, and will leave as soon as the youngsters can fend for themselves. The rest of the year, foxes sleep in open areas so they can see predators coming. It is not uncommon to see a sleeping red fox curled up in a backyard during the day. (If you ever see a fox in a tree, it is a gray fox. Red foxes do not climb trees.) Rat poison makes red foxes more susceptible to mange and other illnesses; if you see a mangy fox, it may have been eating poisoned rodents.

Foxes are an important part of a healthy, flourishing ecosystem. They help keep rodent and rabbit populations in check, do little damage, and do not harm most pets. In some areas in which foxes were eradicated, rodents increased so much that farmers brought foxes back. Foxes avoid people, so if you should happen to catch a glimpse of one, consider yourself privileged to see such an elusive and beautiful creature.

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Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.