The Virginia opossum (Didelphis virginiana) is the only marsupial found in North America, a unique distinction it holds. Commonly referred to simply as “possums,” these animals are often seen scurrying across yards or roads at odd hours. The perception that they are mostly active at night is accurate, as this behavior is deeply rooted in their biology and survival strategy.
Answering the Question: Are Possums Nocturnal?
Opossums are indeed nocturnal, meaning their primary active period for foraging and travel occurs between dusk and dawn. Their eyes possess a high ratio of rod cells to cone cells, noted at approximately 50:1, which significantly enhances their ability to detect movement and navigate in low light conditions. This nighttime activity schedule also serves as a protective measure, allowing them to avoid daytime predators while mitigating the risk of overheating.
While they are almost exclusively active under the cover of darkness, factors like extreme hunger, cold weather, or the presence of young can occasionally prompt crepuscular (twilight) or rare daytime movements. Such instances are exceptions to their standard rhythm, as prolonged exposure to daylight increases their vulnerability.
Nighttime Foraging and Temporary Shelter Use
The opossum’s nocturnal hours are dedicated to opportunistic foraging, supported by an omnivorous and highly varied diet. Their acute sense of smell and excellent memory allows them to locate and return to dependable food sources, which often brings them into contact with human residences. They will consume almost anything, including insects, carrion, fruits, grains, and readily available items like unsecured garbage and pet food left outdoors.
During the day, opossums retreat to temporary shelters, as they do not construct permanent dens or nests. They utilize existing, safe, and dry spaces such as abandoned burrows, hollow logs, rock crevices, or dense brush piles. Their prehensile tail acts as a brace and fifth limb to aid in climbing and provides stability when navigating trees. The popular image of an adult opossum hanging by its tail for extended periods is largely a myth.
Understanding the Science of Playing Possum
The well-known defense mechanism of “playing possum” is an involuntary physical response known scientifically as thanatosis, or tonic immobility. This state is a shock-induced catatonic reaction triggered by extreme fear or neural overload. The opossum’s body collapses into a limp, unresponsive posture, often with a gaping mouth and excessive drooling.
A key component of this response is the emission of a foul-smelling, greenish fluid from the cloacal or anal glands. This noxious secretion mimics the scent of a decaying carcass, which is a deterrent to predators that prefer live or freshly killed prey.
The entire episode can last anywhere from a few minutes to more than an hour, sometimes up to six hours, before the opossum slowly recovers. This physiological shutdown removes the stimulus of a struggle, prompting the predator to lose interest and move on.