Rodents and Other Vertebrates

Rodents and other vertebrates spoil feed, spread disease, and damage structures. These problems are the basis of the need for pest control of these organisms. The biology of common rodents and vertebrates is described here with various control measures.


Rodents

From L-R (top): Norway rat and the roof rat
From L-R (bottom): house mouse and the deer mouse

Rodents such as the Norway rat (Rattus norvegicus), which is the most common and destructive of rodents, has reddish-brown fur with a small head and blunt muzzle.  The Norway rat, like most rodents, is a nocturnal animal, which means it prefers activity at nighttime An adult Norway rat produces three-quarter inch long capsule shaped blunt, ended droppings, weighs about 1 pound, and measures 6 to 11 inches from nose to tail end.

The roof rat (Rattus rattus) is black to yellowish-brown, weighs just under 1 pound and measures just under 7 inches long, which is smaller than the Norway rat.  This rat produces droppings that are ½ inch with sharp ends.

The house mouse (Mus musculus), has a pointed muzzle and produces rod-shaped, sharp-end feces that are 1/4 inch long, about the size of a rice grain.  These rodents are dull gray and weigh up to an 1 ounce.   Mice consume less water than rats, but are more bait friendly.

Lastly, the deer mouse (Peromyscus maniculatus), which spreads hantavirus is a common pest. The deer mouse is 3.8 inch long and spreads hantavirus through the air via urine or droppings, which leads to a severe respiratory state and can death in 50% of cases.  The droppings are more similar in appearance to the house mouse droppings than to the droppings of other rodents.

Rats can squeeze through holes than are >½ inch, while mice can enter holes >¼ inch. Rats are omnivorous, but generally consume items such as meats, pet foods, fish, and stored cheeses. Mice prefer grains, fruits, vegetables, seeds, and nuts, and are cannibalistic, eating the meat from dead mice. If food is available, a mouse will normally travel no more than 10-50 feet from their nest.  This is called the feeding range. The feeding range of the Norway rat is the greatest followed by the roof rat, then the house mouse and deer mice, which have similar feeding ranges.

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Voles resemble hamsters and are called field mice in some parts of North America.

Voles are akin to rodents and measure 9 to 11 inches in length from head to tail.  The meadow vole (Microtus pennsylvanicus) is the most common vole species within Georgia.  Voles prefer plant material over insects, even during winter where they do not hibernate.

Pest control

Elimination of rodent shelters, food, and water controls rodent populations. Treatment of infestations with multi-dose anticoagulants or single-dose toxicants is effective. These rodenticides include baits anticoagulants and fumigants. These chemicals can be acute where a small dose is taken by an animal who dies shortly thereafter or chronic where the animal ingests multiple dosages overtime before death.

Bait stations, that are labeled for rodent control, have temporary usage. Incineration, burying, or trash disposal of carcasses is dependent on the number of rodents trapped. Removal of uneaten bait after the treatment period has ended concludes the management methods.

Birds

From L-R top: The rock pigeon is the only pigeon species that is a pest within Georgia; the English sparrow.
From L-R bottom: European starling and Canadian goose are also shown here.

Most birds are protected from hunting and capture under the laws of many jurisdictions. However, there are three bird species within Georgia that can be managed with pest control measures. This list includes the rock pigeon (Columba livia), which is colored grey and white, 11-15 inches long with a nearly 2-foot wingspan. Next, are the English sparrow (Passer domesticus), which measures 6 inches long and the European starlings (Sturnus vulgaris) that measures nearly 8 inches. Both of these bird species are considered agricultural pests for their presence and feeding on croplands. Lastly, Canadian geese (Branta canadensis), which are common across the U.S., are between 30 to 43 inches in length and have a nearly 6-foot wingspan. These birds contaminate and eat feed, harm ornamental plants, damage structures, and act as vectors of human disease. Geese are also very obtrusive and aggressive, tending to badger nearby humans for food. As migratory birds, Canadian geese are protected by U.S. federal law from hunting and capture outside of prespecified hunting seasons.

Pest control

Because of the possibility of harming protected bird species and other non-targets, the use of exclusion methods and addressing sanitation issues instead of the application of poisons and baits is preferred for managing these nuisances. We recommended that property owners secure entrances to structures. Repellents and barriers to prevent birds from entering domesticated spaces are also helpful. Traps have also proven to be effective and safe. Lastly, wastes and foodstuffs should be properly disposed of and removed from areas where birds frequent.

Other Vertebrates

The little brown bat is the most common bat in the U.S. and within Georgia.

There are several species of bats of the order Chiroptera which are indigenous to Georgia. Bats are nocturnal animals like rodents. These bats spread histoplasmosis, a disorder of the lungs, as well as rabies and require control because of their large number. Bats, however, are also beneficial to the environment by feeding on pest insects, such as moths and beetles.

The little brown bat (Myotis lucifugus), which is the most common in Georgia, is small with a wing width of 8 inches, and a weight of less than half an ounce. The females form large maternal colonies, often under the roof of buildings and barns. The offspring are born in June and can take flight by late summer. Although the lifespan can be up to three decades, most wild bats live about seven years. Bats hibernate and overwinter as adults.

The striped and eastern spotted skunks are native to Georgia.

Skunks are considered pests because they damage turfgrass, spread rabies, and other parasites, as well as invade structures where humans live. Skunks, which are also known for their obnoxious odor, fall into three genera under the family Mephitidae. The striped skunk (Mephitis mephitis) and the eastern spotted skunk (Spilogale putorius) are the two skunk species that are native to Georgia. The striped skunk measures about 21-28 inches in length and weighs about 3-11 lbs, while the eastern spotted skunk is smaller, measuring just under 24 inches at 1 to 3 lbs according to the Georgia Department of Natural Resources.

The eastern gray squirrel is a pest under Georgia law and can be hunted for game from Aug. 15-Feb 28 according to Animal Law Source.

There are four species of squirrels of Georgia that damage electrical wiring, gardens and flowering plants when nuts and acorns are not available. The most common squirrel species in Georgia is the eastern gray squirrel (Sciurus carolinensis), which leaves in nests called dreys, and measures just under 2 feet in length from head to tail.

The eastern mole is one of two species of moles that inhabit Georgia.

Two species of Georgian moles damage ornamental plants as well. These include the star-nosed (Condylura cristata) and eastern moles (Scalopus aquaticus). Resembling rodents, moles are about 4 to 6 inches in length with approximately 1-inch tails. The star-nosed mole is relegated to northeast Georgia, while the habitat of the eastern mole includes all regions of the state.

The eastern indigo snake with characteristic red marking under the chin.

The eastern indigo snake (Drymarchon couperi) is non-venomous and the longest snake in North America, measuring up to 8 feet.  The eastern indigo snake is bluish-black in color with a characteristic reddish marking under its chin. The eastern indigo snake is listed as threatened species at the state and federal levels.  A threatened species is one whose population in the wild is near endangered. 

Other vertebrate pests of ornamental plants include voles, deer, and rabbits.

Pest Control

Mechanical controls, such as exclusion, include the closing of entrance openings to dwellings to prevent bats and the use of lighting and repellents in nesting areas which are all highly useful. These methods also work well for skunks, squirrels, moles, voles and snakes, which may enter dwellings. 

When in an area where the bat guano is present, protective clothing and  a cartridge respirator, with filters of 0.3 micrometers (µm), should be worn.  The guano should be sprayed with water to loosen it before  removal.

If these animals invade your property, and these methods are not effective, please contact the Georgia Department of Natural Resources, Wildlife Resources Division, Game Management Section Headquarters at (770.918.6416).

You may also contact the nearest University of Georgia Cooperative Extension office or call your local animal control service.

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