The North American opossum, Didelphis virginiana, is the only marsupial found north of Mexico. These mammals are highly opportunistic when seeking shelter, often exploiting structural weaknesses to gain entry into human dwellings. The direct answer to whether they can squeeze through small spaces is yes, a capability that often surprises homeowners given their medium size. Understanding this flexibility is key to preventing them from taking up residence in your attic or crawl space.
The Physical Mechanics of Flexibility
The opossum’s unusual flexibility stems from a unique combination of skeletal features designed for an arboreal and scrambling lifestyle. Unlike many mammals, the opossum possesses a highly mobile scapula (shoulder blade), which allows for a much greater range of motion. This mobility is a significant factor in their ability to compress the width of their upper body when passing through narrow openings. Their segmented spinal column also contributes, allowing for considerable lateral and dorsoventral bending. This loose skeletal coupling, combined with relatively loose skin, enables the animal to flatten or elongate its body profile.
Determining the Minimum Gap Size
Translating the opossum’s flexibility into a practical measurement reveals a surprising capability for an animal that can weigh up to 14 pounds. The general rule is that if the animal can fit its head through an opening, the rest of its body can follow. The skull of an adult opossum is narrow and can be manipulated through spaces approximately 3 to 4 inches in diameter. This minimum clearance is comparable to the size of a tennis ball opening. Younger opossums may fit through even tighter voids, with some reports suggesting gaps as small as 2 inches.
Securing Common Access Points
Opossums exploit vulnerabilities in a home’s exterior to gain shelter, targeting several common access points:
- Rooflines, especially where fascia boards or soffits are loose or rotted, providing direct access to the attic or wall voids.
- Damaged foundation vents or those with missing screens, which are frequent entry points into the crawl space.
- Gaps around utility lines (pipes, cables, or wiring) that penetrate the siding or foundation if the sealant is degraded.
- Uncapped chimneys, unsecured pet doors, and openings beneath porches or decks.
Effective Exclusion and Sealing Methods
Effective long-term prevention involves sealing all potential entry points using durable materials resistant to the opossum’s strength. For sealing vents and wide openings, heavy-gauge galvanized hardware cloth is recommended over standard chicken wire. A mesh size of 1/2 inch or 1/4 inch is necessary to prevent entry. For foundation gaps and utility entry areas, metal flashing or a concrete patch should be used to create a permanent barrier. It is necessary to inspect the entire structure and confirm the animal has left before sealing the entry point. Trapping an opossum inside will cause damage as the animal attempts to escape or perishes in the space.