Northern wood rats, often called pack rats, are known for their habit of collecting objects and building large nests. These rodents can become pests when they invade homes, garages, or sheds.
They can cause structural damage and pose health risks through contamination.
The Suburban Hoarder: Northern Wood Rats
The Northern Wood Rat (Neotoma cinerea), famously known across the Western United States as the Bushy-Tailed Packrat, is a charismatic yet destructive rodent. Unlike the scaly-tailed “true” rats (like the Norway rat) found in cities, the Northern Wood Rat looks more like a large, oversized hamster with a squirrel-like tail. In the U.S., they are legendary for their “kleptoparasitic” behavior—the compulsive habit of stealing shiny objects and caching them in massive, messy nests called middens.
Identification: The “Bushy-Tailed” Distinction
Identifying a Northern Wood Rat is relatively simple because they lack the “greasy” appearance of common pest rats. They are adapted for rocky outcrops and high-altitude forests of the Northwest and Intermountain West.
- The Tail: Their most defining feature is a thick, furred, bushy tail that can be up to 7 inches long.
- Physical Build: They have large, rounded ears, long whiskers, and soft, fine fur that ranges from pepper-gray to cinnamon-brown. Their undersides and feet are almost always stark white.
- The “Swap” Myth: Packrats are famous for “trading” items. In reality, if a wood rat is carrying a stick and finds a shinier object (like a silver spoon or a coin), it drops the stick to pick up the better prize, leaving the impression of an intentional trade.
The Midden: An Archaeological Fortress
The “nest” of a Northern Wood Rat is not just a bed; it is a structural fort called a midden. These piles of sticks, rocks, and debris are cemented together by the rat’s own crystallized urine (known as “amberat”). In the dry climates of the West, these middens can persist for thousands of years, providing scientists with a “time capsule” of ancient plant life.
U.S. Property Damage and Health Risks
While they are “cuter” than city rats, their presence near U.S. homes is a serious concern for two reasons:
- Electrical Destruction: Packrats have a notorious affinity for the wiring in car engines and HVAC units. They often nest in engine bays, chewing through expensive wiring harnesses to use the insulation for their nests.
- Disease Vectors: In the United States, wood rats are primary hosts for the Sin Nombre Hantavirus and can carry Plague-infected fleas. Their middens also attract “Kissing Bugs” (Triatoma), which can transmit Chagas disease.
Management: The “Tidiness” Defense
In states like Arizona, Montana, and Idaho, managing packrats is about removing the “building blocks” of their fortresses. Management strategies include:
- Habitat Modification: Clearing away piles of firewood, lumber, and dense desert scrub (like prickly pear) from within 30 feet of the house removes their primary nesting sites.
- Engine Protection: For vehicles parked outdoors, leaving the hood open or using strobe lights/ultrasonic repellers can discourage rats from nesting in the engine bay.
- Trapping: Large “rat-sized” snap traps or live traps are effective. However, relocated rats rarely survive, so exclusion and habitat removal are the only long-term solutions.
Identification
Medium-sized rodents with bushy tails and large eyes.
Damage
Gnawing, nesting, and contamination of stored items.
Control
Seal entry points, remove nesting materials, and use traps.