Roof Rat

Rattus rattus

roof rat

Roof Rat, photographed at Green Cay Nature Center, Boynton Beach, Palm Beach County, in May 2017.

It is kind of weird to see a rat foraging through a tree, but for Rattus rattus, AKA the roof rat and many other names, it ain't no thing. Unlike the better known Norway rat, who is at home in the sewers, this guy makes his living up where it's high, particularly in trees.

This is also the rat that's generally blamed for one of the worst catastrophies to ever hit humanity: the plague, the black death that periodically swept through Europe for hundreds of years. (One study we've seen that focused on climate data actually says Asian gerbils might the villains, not rats. But it didn't go so far as to let rats completely off the hook.)

The roof rat is the most prevalent nonnative rat in Florida, found in all 67 counties. It's found throughout the southeastern United States as far north as Virginia and west to Texas. It's also found along the Pacific Coast, California to Washington. By contrast, the Norway rat is relatively rare here in the Sunshine State.

There are three color morphs of roof rats found in Florida — black, gray and brownish gray. Regardless of the color, an adult roof rat will go between 12 and 14 inches long, with a tail longer than its head and body combined. They are less dependent on humans than the Norway rat, and quite able to get along in the wild. Roof rats are omnivores, but they have a special taste for fruit, and it's not limited to wild varieties. They'll eat apples, oranges, tomatos, mangos and a whole bunch more. A tell-tale sign that they've been nibbling in your garden/orchard/farm: fruit will have a round hole in them about the size of a large coin, with the inside hollowed out.

They will eat insulation. They will eat wiring down to the metal. They will eat garbage. They will even eat through lead pipes to get to the water. As the Invasive Species Copendium puts it, "It will feed on and damage almost any edible thing." And apparently some usually considered inedible. They are blamed for, or contributed to the extinction of "many species of wildlife," including birds, reptiles, bugs and plants, according to the ISC. They're a major threat to avaian life on islands in particular. Fortunately, they do have their share of predatory threats, including cats, owls and our personal favorite, the rat snake.

Roof rats are excellent climbers, their abilities similar to squirrels. They'll nest in tree cavities, but also in attics, in gutters and down spouts. Roof rats will take to the ground but they aren't the burrowers that Norway rats are. The average life span of a roof rat is about year — short but long enough to qualify for great grandparenthood status. Roof rats are sexually mature at three or four months; a female is capable of having four or five broods in a year, each with five to eight offspring each. Gestation period: about three weeks.

Roof rats might be off the hook for the black death, but they still major disease carriers. Rats as group are known to harbor more than 40 diseases that can infect humans. Over the last 1,000 years, they are believed responsible for more human deaths than all wars and revolutions combined.

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Published by Wild South Florida, PO Box 7241, Delray Beach, FL 33482.

Photographs by David Sedore. Photographs are property of the publishers and may not be used without permission.