Years ago, when we owned a dog, we fed him on the back porch. One early April evening we heard a commotion outside. I opened the kitchen door and saw Fritz sniffing at an opossum, which was laid out flat on its side, its eyes tightly shut, its mouth stretched in a gruesome grin that exposed its front cheekteeth, and its tongue lolling. While I knew about “playing possum,” Fritz did not, and he looked as puzzled as a dog could. I called him into the house and watched from the window for over ten minutes until the opossum slowly roused itself, remained still for another couple minutes, and then ambled away, none the worse for its encounter.
More recently, opossums come to our back porch on late winter and early spring evenings for spilled birdseeds and usually shamble off instead of playing dead if I open the door. They also like to visit our compost pile for tasty tidbits.
By April, those that have survived the winter are not only very hungry, especially if it has been unusually cold, but if they are females, they are already carrying little ones in their pouches. Most studies show that opossums cannot survive outside if the temperature dips below 19 degrees Fahrenheit, so they spend those cold days and nights tucked in a warm den that once belonged to a woodchuck or other burrow-digging animal. They line it with grass and leaves, which they gather by grasping them in their mouths and then passing them under their body to their tail. They use their tail to transport the materials to the den, a behavior that even youngsters at 88 days of age can master.
However, they don’t hibernate so if they can’t go out, they don’t eat. And if they lose more than 42% of their pre-winter body mass, they starve to death. One researcher calculated that opossums could spend no more than 70 winter days in a den before they might die, and they needed at least 50 winter days to forage in order to make it through the winter. However, those 50 days had to be well-spaced throughout the winter. Furthermore, the more fit an opossum is when winter begins, the more likely it is to survive.
Despite such dire predictions, opossums have managed to expand their range 500 miles northward in the eastern United States since the Colonial Era. Before European settlement, they lived no farther north than Kentucky, Indiana and Ohio. Today they are found as far north as Wisconsin, Michigan, New York and southern New England. But in those northern areas, they are liable to be suburban and urban residents where garbage and fruit-bearing shrubs and trees are readily available, according to a study by L.L. Kanda in Amherst, Massachusetts.
Opossums are renowned for their small brains, which humans have equated with stupidity. Not so, say some scientists, including Steven Austad, who designed four runways, only one of which was connected to a food box. Of the cats, chicks, dogs, goats, pigs, rabbits, rats, turtles, and opossums that he tested, opossums scored highest in their ability to remember where the food box was.
Another researcher, Scott Camazine, when he was at Cornell University, fed opossums poisonous mushrooms that they not only quickly tasted and rejected but remembered as bad food for as long as a year.Penn State ecologist Richard Yahner, in his book Fascinating Mammals, says that…”based on some learning and discrimination tests, some scientists go as far as to contend that the intelligence of Virginia opossums is higher than that of dogs and equal to pigs…” At least as far as their tummies are concerned.
The Virginia opossum, also called “white face,” is one of 70 extant possum species, but the only marsupial that lives in North America. Yet 35 million years ago at least three families, five genera, and 13 species of marsupials lived here. In fact, some scientists believe that marsupials may have originated in North America and most certainly in the Western Hemisphere. But for unknown reasons, marsupials became extinct in North America 15 million years ago, even while they continued to radiate successfully in Central and South America as well as in Australia and New Guinea in the Eastern Hemisphere. Today our hemispheric southern neighbors have close to 80 marsupial species or 30% of the world’s marsupials.
About 75,000 years ago, our Virginia opossum (Didelphis virginia) diverged from its ancestral species, the still flourishing common possum of northern South America (Didelphis marsupialis). One of three species in the genus Didelphis, which is Greek for “double womb,” the third is Didelphis albiventris, the white-eared opossum of southern South America.
Because the explorer John Smith in 1612 first saw the Virginia opossum in Virginia, its species’ name is virginiana. “An Opassum,” Smith wrote, “hath a head like a swine and a taile like a Rat, and is of the Bigness of a Cat.” The name “opossum” comes from the Algonquian “apasum” meaning “white animal,” even though opossums are mostly gray except for their cone-shaped faces. Young opossums, with their bright, black eyes, perky, dark, shell-like ears, and pink noses are apparently endearing to some people, and the National Opossum Society of Catonsburg, Maryland sells a variety of opossum-themed items to what appears to be an expanding fan base for opossums.
But their long, naked, rat-like, prehensile tails that allow them to hang from trees repulse other people. They also show unbecoming signs of old age such as cataracts, weight loss, ears shriveled from frost bite, and lack of motor coordination by the time they are two years old. Those females that are still alive have atrophied reproductive organs. This leads to smaller litters, more female than male young, and often the inability to conceive at all.
For their size-on average four to ten pounds-opossums are incredibly short-lived mammals. But during their reproductive span, they are also incredibly prolific. Here in Pennsylvania, opossums usually have two families a year-in late February or March and June or July.
Males continually make a clicking sound when pursuing a female, the same sound they make in aggressive encounters with other males and that females use in communication with their young. Even though males have half as many sperm as other mammals of their size, their unique, forked penises deliver spermatozoa to the paired uteri of the females during mating, which lasts 20 minutes.After only a 12-to 13-day gestation period, as many as 25 tiny young are born to the sitting mother, her neck arched and her head down. Although they are the size of raisins and are blind, deaf, pink-skinned, and hairless, these “living embryos” have well-developed front legs and sharp claws. Using legs and claws, they climb hand over hand in a swimming motion up the belly hair of their mother and into her pouch–a distance of two inches which takes them about 16 and a half seconds. Not all of them make it and those that do find only 13 nipples to grasp. Once a youngster grabs a nipple, it enlarges and forms a bulb inside the young one’s mouth that remains attached for two months. Within a month, only seven or eight youngsters survive in the pouch, probably because not all the nipples are fully-functional. During that time, their mother moves from den to den and from food source to food source all the while her young are nursing.
Their eyes open at 58 to 72 days of age when they are able to climb out of the pouch. Then they grab their mother by her fur and ride on her back for another two to four weeks. During that time they eat some solid food, and at 100 days of age they are weaned and on their own. But most stay in the brushy vicinity of their weaning den for several months, where they have learned about food sources from their mother, before moving from den to den as adults do. Nevertheless, less than half the youngsters survive the rigors of food-gathering and predator-dodging.
Opossums are mostly abroad at night, foraging in brushy edges or along small permanent or intermittent streams such as our stream. John Seidensticker, who followed radio-collared opossums in Virginia’s Blue Ridge Mountains, discovered that rural opossums would trek to new foraging areas night after night. Females, even with young in their pouches, traveled as far as a mile or more. Males ranged even farther and faster. On average males covered 25 acres on a summer night and females ten acres. But in suburban or urban habitats, where garbage is readily available, opossums may never move.
In the country they eat insects, small mammals, fruits and berries, especially blackberries, apples, and persimmons, amphibians, earthworms, birds, green vegetation, bats, carrion, and snakes, including rattlesnakes, copperheads, and water moccasins because opossums are immune to Western Hemisphere pit viper venom. In parts of Texas, six percent of their diet consists of copperheads.
Opossums, in turn, are eaten by dogs, great horned owls, coyotes, foxes, bobcats, raccoons, and raptors. Most deadly of all, though, is the automobile, especially when an opossum is feeding on road-killed carrion. We often surprise opossums on our road when we are driving home at night and inevitably we must stop and wait patiently until they find their way off the road.
They rely on their super-sensitive noses to find food, and biologist Donna Holmes, who studied captive opossums, discovered that they excrete strong odors, which they use to mark their home range and signal prospective mates. They also follow their noses in search of dens and escape routes.In addition to clicking, opossums hiss, growl, screech, and bare their teeth when defending themselves or encountering other aggressive opossums. They even sometimes extrude a greenish substance from glands near their vent, especially when they are playing dead, but scientists do not know what it is or why they do it.
Altogether, opossums are remarkable animals as Seiedensticker discovered during his five-year study. “I assumed,” he wrote, “they were slow and simple creatures… [but] the supposedly primitive opossum turned out to be a lot more efficient and sophisticated than I had anticipated.” Feeding and breeding, he concluded, are what they do best. Because of their single-minded pursuit of food and their efficient breeding system, they have been able to not only survive but thrive in a wide variety of habitats.
Opossum illustration courtesy of U. S. Fish and Wildlife Service/Bob Savannah
Every fall, in early November, I hang two bird feeders from our back porch latticework. One is an open, wooden platform feeder that has been batted apart at least three times by black bears and patiently repaired by my husband Bruce. That feeder is now almost 34 years old and has great sentimental value to us. The birds also prefer it to our other feeder that is a sturdy tube reinforced by steel mesh and is, so far, bear proof. Both feeders are filled with oil sunflower seeds.
On the back steps and ground below, I scatter mixed seeds of millet, cracked corn, and sunflower. That setup attracts a diversity of bird species and some mammals too. During the daytime, I’ve watched cottontail rabbits, gray squirrels, chipmunks, eastern meadow voles, deer, opossums, and short-tailed shrews eat seeds. Some, like the voles and shrews, locate their burrow entrances in the midst of the spilled seed and pop in and out of the ground like jack-in-the-boxes.
A ten-foot-tall juniper bush in front of our bay window near the back porch provides cover and nighttime roosting for dozens of birds, particularly dark-eyed juncos. Sometimes, though, a junco is confused by the light shining through the window and flies repeatedly into the glass. That’s what we thought was happening one evening in late November three years ago.
First one junco, then another, repeatedly hit the window. They seemed to be having trouble settling down for the night. Even when we turned off the inside light, the thumps continued.
Finally, our son Dave turned on the porch light. To our surprise, a red phase eastern screech owl, which had been perched on the open, bulkhead door next to the back porch, took off. No wonder the juncos had been jumpy. Screech owls are known predators on songbirds. But since that screech owl had been situated above the seed-strewn ground, we suspected that its intended prey were the rodents that surface to feed throughout the night.
After that experience, we became occasional nighttime watchers of our bird feeding area, especially during a six week winter visit by our then year-and-a-half old granddaughter, Eva, and her parents. She, like her father and two uncles had when they were children, spent much of the daylight hours watching the birds and animals from the back door window.
Our nighttime watching consisted of turning the back porch light on after supper to check for visitors. Usually we saw nothing. But on December 8 there was a southern flying squirrel eating seeds on the back porch. Eva had already been thrilled by gray squirrels during the day, but there is no small mammal more beguiling than a big-eyed, flying squirrel. This one seemed unafraid of the excited little girl and continued eating as we watched.
Three nights later it brought a friend. One sat in the wooden feeder eating seed while the other ate on the back porch itself. Eventually, they climbed to the top of the porch, spread their patagia or gliding membranes, and volplaned into the night. No doubt they had a nest in a nearby tree cavity, and our bird feeding station was one of several stops during their nocturnal search for food.
That was the last we saw of the flying squirrels, although they may have shifted their schedule and fed later in the evening. Since we only checked occasionally between 6:00 and 8:30 p.m. on some evenings we probably missed many late-night visitors.
However, we didn’t miss a return visit from a screech owl on the tenth of January, only this was a gray phase bird. It sat on the roof of the wooden bird feeder while one scared junco flew back and forth under the porch roof. The screech owl seemed supremely uninterested in the songbird. But it gave all of us, including Eva, a good, long look before flying off.
Unfortunately, she was not here last winter when we had almost continual, early evening visitors from November until March, and, because of their distinctive appearances, we knew they were the same animals. It all began as Bruce, Dave, and I sat eating dinner in the kitchen on November 11. Suddenly, there was a loud thump on the back storm door. We rushed to turn on the porch light and were in time to watch an adult raccoon beheading and eating a junco that had been roosting in the latticework above the wooden feeder. The raccoon totally ignored us and tore into the junco as if it were starved, leaving only a few feathers as evidence of its deed.
A week later, at dusk, three young raccoons appeared on the back steps to eat bird seed. Turning on the porch light didn’t deter them. Neither did opening the squeaky, inside door, sitting on a chair, and watching them through the screened storm door. When the telephone rang, they looked up briefly. When I talked to them, they also glanced up and sometimes retreated back down a step or two, but they were soon back and looking in at me as I clicked my tongue at them. Finally, after an hour and twenty minutes and some staring intently into the night, they left.
Young raccoons usually spend the winter in a communal nest with their mother and sometimes other raccoons, as many as 23, in a state of semi-hibernation, having built up a layer of fat to sustain themselves during winter food shortages. Those dens are most often in hollow trees but will also be under tree roots, in rocky crevices, or in remodeled woodchuck, opossum, fox, or skunk dens.
In reality, those raccoons probably lived under the guesthouse along with a skunk, an opossum, and a porcupine, according to Dave. He lives above this mammal condominium and spent the winter listening to the assorted bumps, snarls, screams, and hisses below his bedroom and examining the snow for tracks so he could positively identify his fellow boarders.
Throughout November the triplets, as we called the young raccoons, visited most evenings, but we never saw an adult. Often, though, they would seem to be disturbed by something in the forest and would leave. Sometimes I thought I heard a faint sound. Was their mother warning them off? Had she been the visitor that had beheaded the junco?
Then, on December 2, a young opossum came to the back porch to eat seed. Unlike the triplets, it barely tolerated the porch light. Any sight or sound of us sent it back down the steps with many a backward, hesitant look. Since young opossums only stay with their mothers three months, this one was on its own. Although opossums don’t hibernate, they are relatively inactive in late autumn and winter, staying in nests of grass and leaves, or so the experts say. Because they are southern animals and have a difficult time if the temperature dips below 19 degrees Fahrenheit, opossums that live through a northern winter usually have deformed ears, and even tails, because of frostbite.
This opossum seemed to time its arrival before or after the triplets’ visit. On December 4 the triplets came shortly after dusk and the opossum at 8:30 p.m. The next evening the triplets came in at 8:15, staying until our bedtime. Then, for most of December, the opossun arrived around 6:30 p.m., ate its fill, and left. As soon as it was gone, at 8:00 p.m., the triplets appeared. By morning all the seeds on the steps and ground were gone.
Raccoons are known to be peaceable creatures with no sense of territoriality. Virginia Holmgren, who actively fed raccoons all year long from 1960 until 1981, observed 145 young and their mothers, and claimed, in her charming book, Raccoons, that her raccoons fed peacefully with opossums whenever they appeared.
We had to wait until the following March 3 to see how raccoons and opossums interacted. That evening Bruce and I were busy in the front yard watching the moons of Jupiter, the Orion nebulae, and the Pleiades star cluster through our new birding scope. All the while we were admiring the incomprehensible universe in the front yard, a raccoon and opossum, at opposite ends of the feeder area, were filling their bellies. No aggression there, but I did see aggression between the triplets on December 14. Two of them pushed the third one off the steps, but it didn’t protest. It merely fed quietly on the ground below its siblings.
On the evening that autumn became winter, the triplets appeared for what we thought was the last time. But the opossum continued visiting throughout the winter months even though its coat looked too thin to get it through the cold. In places its skin showed through like a balding old man with a few strands of gray hair plastered carefully over his head. We didn’t always see the opossum, but, unlike raccoons, which never defecate in their feeding area, it left a pile of its scat on the porch and steps every night.
During the cold weeks of early January, when the temperature dipped into the single digits, the opossum continued to visit. By January 18, it ate as if half-starved and no longer reacted either to the porch light or my comments to it. The thermometer registered a mere seven degrees Fahrenheit, proving that opossums can not only survive temperatures below 19 degrees but move around and feed in the bitter cold.
Then, on the morning of February sixth, I went outside while it was still dark to retrieve the bird feeder containers from the back porch. An animal rushed away, using mincing steps that reminded me of a Chinese woman with bound feet, a white fur clinging fashionably to her back. But it was a striped skunk, its tail streaming out straight behind it as if it wouldn’t think of threatening anyone on its home ground, which seemed to be under our front porch.
I caught no whiff of skunk, and when I returned from our basement, where I store our birdseed safe, I turned on the porch light and cautiously looked outside. The skunk was back, eating seeds on the cement pad in front of the bulkhead door, its white, muff-like back and tail gusting in the breeze. It ate as if starved and only retreated when the first birds appeared in the dim, predawn light. Like the skunk Bruce had photographed at our feeders the previous March, it had a white back, sides, and tail, a black belly, and a black face divided by a single, longitudinal white nose stripe.
Although skunks will eat seeds, their principal winter foods are mice, voles, and shrews. I wondered if the skunk was more interested in eating the creatures that ate our seeds. Skunks, like raccoons, also build up fat before winter so they can snooze through fierce winter weather. But they do get out and forage on milder days and, as I discovered, on cold (23 degrees) nights as well.
Skunks, too, usually nest communally in a single den (as many as 15), so I wondered if there was more than one in the den under our front porch and what relation it had to any living under the guesthouse.
“A raccoon,” Holmgren writes, “might snarl at another raccoon poaching on its corner of the bowl, but not at a skunk. The smaller animal had a right that…raccoons were too smart to defy.” On March 2 we had a chance to test her statement. I switched on the porch light at 8:30 p.m. and found that not only were the triplets back, but so was the skunk. The raccoons moved menacingly toward it as it tried to feed on the steps. Instantly its tail shot up, it stamped its front foot, and then turned away.
I held my breath. But instead of spraying, the white skunk made a dignified retreat, its tail still high in the air. I couldn’t decide whether the raccoons were intimidated by the skunk’s threat of its ultimate weapon, but when it quietly returned a few minutes, later, its tail was down and it fed peacefully off to the side of the raccoons just above the bulkhead door. They were still eating harmoniously when I went upstairs to take my shower. Later, when I opened my bedroom windows, there was not even a faint whiff of skunk.
That was the last we saw of the skunk and the triplets, but the opossum appeared once more shortly after dark on March 19. It scarfed up birdseed like a vacuum cleaner. Clearly it was very hungry, as most mammals are by March.
I could only hope that those creatures that had made our night time feeder watching entertaining throughout the winter survived the harshest winter month of all.