OUT IN THE WOODS

Possum walking in a field, picking up to 4,000 ticks a week—
it will eat them all for snacks!
Photo: Diane Borden-Billiot, USFWS

These Nighttime Foragers Love Ticks
By Kevin Mckeon, Maine Master Naturalist

Hate ticks? Then love those opossum!
About three million years ago, a continental collision formed the Isthmus of Panama, connecting North and South America, and enabling The Great American Biotic Interchange. Deer, bear, wolves, cougars, and others moved to South America; armadillo, porcupine and others moved north, including the 70-million-year-old opossum.

Algonquian for “white animal” (also called possums) these are the only marsupials in North America. They grow one to three feet long—nose to tail—and weigh 1.5 to 14 pounds, with the larger opossums to the north. Their prehensile (capable of grasping) tail is used while climbing trees and gathering leaves and other bedding materials. Opossums are solitary, but sometimes huddle together as families in burrows, and will remain in an area as long as food and water are available. Possums are the only mammals, other than primates, with opposing “thumbs” on their feet, making them great climbers.

After birth, the 18-25 bee-sized babies climb up into their mother’s pouch and attach to one of her 13 nipples. The nipple expands to fill the baby’s mouth, holding it in place, allowing a baby to nurse for another 70-125 days. Five to 13 may live to emerge from the pouch. They’ll live up to two years, avoiding raptors, snakes, foxes, coyotes, raccoons, dogs and cats. A separated or distressed baby makes a sneezing noise; the mother will respond with a clicking sound and waits for the baby to find her. A baby may also open its mouth and quietly hiss at a threat. The young will sometimes hold on to their mother’s back while she travels.

These nighttime foragers are able to live in many areas under different climatic conditions due to their varied diet. With 50 sharp teeth, they’ll eat rodents, frogs, birds and bird seed, pet food, garbage, berries, fruit, meat, roadkill, and insects including ticks. Scientists have found that possums’ activities act like tick magnets, and being fastidious groomers, they scratch the ticks off and eat them—as many as 4,000 ticks a week!

Evolving in the tropics, opossums don’t store fat as well as other North American mammals, so they can freeze at 19 degrees Fahrenheit. Cold nights limit their foraging, and with very little stored fat to supply energy, extended cold kills them. Those that live near people are safer, making use of our warmer sheds, digging little dens under porches, stairs, outbuildings, and other human-related cubbyholes.

Wrongly perceived as a giant, dirty, scavenging rat, these harmless creatures have many endearing qualities. Tests rank its intelligence at pig level, above cats and dogs, and they are clean animals, using their tongue and paws to groom themselves frequently and thoroughly. Due to their low body temperature, opossums are highly resistant to rabies, a virus requiring a high body temperature. They are also odorless, except when…

…“playing possum”. This involuntary response happens when adult possums are threatened. They roll over, become stiff, and curl their lips to bare their teeth, as saliva foams around the mouth and a foul-smelling fluid is secreted from glands. Their eyes may or may not close. The catatonic state can last for up to four hours and has proven effective as a deterrent to predators looking for a hot meal. Sometimes when threatened, opossums run, growl, belch, urinate and defecate.

So, if you’re lucky enough to have possums pay you a visit, consider their harmless presence a gift of health to you and your family. Maybe even reserve a “possum cubbyhole” for their survival; the springtime tick population will absolutely hate you!