Bald Head Island's Bug Lady

BIOLOGY

 

Animal	Color	Size, weight, shape	Other Features
House mouse   (Mus spp.)	Uniformly light brown to dark gray; occasionally a little lighter on the belly	5 to 7 inches, ½ to 1 ounce,    slender, agile	large ears, small feet and eyes in proportion to the body; sparsely hairy tail.
Norway Rat (Rattus norvegicus)	Dark brown to black	12 to 18 inches (including tail), 12 to 16 ounces, stocky, ears are small and hairy.	tail is shorter than its head and body length, is a larger, heavier rat, with smaller eyes and a blunter snout than the roof rat, dropping are large and ovoid.
Roof Rat (Rattus rattus)	Dark brown to Black	13 to 18 inches (including tail), 5 to 9 ounces, slender, ears are large and nearly hairless.	tail is longer than its head and body length, thinner and lighter than Norway rat, droppings are long and cylindrical.

Roof rats and Norway rats have similar life histories and habits. Their differences are important for management purposes, however, the differences will be highlighted. Rats have poor vision. Rats are wary of anything new that appears in their territory, avoiding the new object for a few days until the rats become familiar with it.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LIFE CYCLE:

A mature female rat can give birth to about 20 young in a year (4 to 6 at a time). The average life span of a rat in the field is less than one year, with females living longer than males. The young are born in nests. They are hairless and their eyes and ears are closed. Within two weeks their eyes and ears open, they grow fur, and they begin exploring the nest area. In the three week they begin to switch to solid food, and imitate their mother to learn pathways to food, escape routes, and danger zones.

 

Young are totally weaned when 4 or five weeks old. They then weigh about an ounce and a half. At three months the young are independent of their mother and able to mate and continue the cycle, either in the same location or after migrating to a new, unoccupied are.

 

Outdoor populations tend to peak in summer to early fall. Indoor populations may remain at the same levels throughout the year, limited only by periodic shortages of food, water, or nesting sites.

 

Root rats may breed throughout the year, but more commonly in warm months. Gestation lasts 20-22 days. The size of the litter usually 4-8 pups. A female may breed at 2-5 months of age and have an average of 5.4 litters per year. Life span in the wild is usually 9-12 months.

 

RANGE:

Rats commonly travel 100'-150' from their nests looking for food and water and patrolling their territory. They may have several "hotel" nest sites in an area and will move from home base to spend several days in one of these secondary nest sites.

 

FOOD SOURCES:

Garbage is an excellent food source for rodents. Receptacles should be rodent-proof: rust resistant, water tight and have tight fitting lids. Trash receptacle storage areas should be free of gaps and encased in hardware cloth/galvanized mesh metal screen. Fallen fruits and nuts are favorites. Bird feeders should be removed and residue cleared nightly. They also consume: snails, garden vegetables and dog droppings. Feed pets away from vegetation and harborage areas. Do not leave pet food out overnight.

 

SOCIAL BEHAVIOR:

Rats are social animals and live in colonies with well defined territories that they mark with urine and glandular secretions. Rats are aggressive, and social conflicts are most common at feeding sites, prime nesting sites, and territorial boundaries. Females fiercely defend their nest and young from other rats.

 

ENVIORNMENTAL CONDITIONS THAT FAVOR DEVELOPMENT:

The Norway rat and the Roof rat have different nesting and feeding preferences that should be considered when management programs are formulated.

 

 

Animal	Nesting Requirements	Food Preferences	Other environmental conditions needed
Roof Rat	nest outside in trees, woodpiles and debris, and in dense vegetation. Inside, roof rats prefer to nest in the upper levels of a building in the attic and ceiling	Have more vegetarian preferences. Typical food is fresh plant material, nuts and seeds, fruit and vegetables and tree bark.	Quite, isolated nesting site near water and food sources.
Norway Rat	nest either inside or out; Outside, they form burrows usually less than 18 inches deep. Also nest in sewers and storm drains. Nests inside are found in lower floors, crawl spaces, storage rooms and/or in any cluttered area that is little used.	More likely to eat garbage than roof rats. High protein foods such as fish, meat, nuts, grains, pet food and insects.	Good nesting sites within 100 feet of water and food sources.

NATURAL ENEMIES:

Dogs, cats, snakes, birds of prey, and other rats.

 

MEDICAL IMPORTANCE:

Rats can spread disease. Sometimes they transmit disease directly by contaminating food with their urine or feces or by biting people. Sometimes they transmit disease indirectly, as when fleas bite a disease-infected rat, then a person. Some of the important diseases associated with commensal rats are: Plague (not currently a problem in the NE USA), Rat-Bite Fever (a seldom serious bacterial infection that occurs occasionally after being bitten by a rat.), Salmonella Food Poisoning (a problem where rats have access to human food sources), and Leptospirosis (another disease that is spread to humans through contaminated food, water, and through cuts in the skin).

 

POTENTIAL DAMAGE:

Rat burrows can cause structural damage by undermining the foundations of buildings, roads, and walkways; can cause damage by gnawing, damaging plastic and lead pipes, door frames, upholstery, and electric wires; and cause damage through the destruction and contamination of food crops and stored foods.

 

THRESHOLD:

The Roof and Norway rats are not native to the United States and are thus considered to be exotic. For that reason, the sighting of just one Norway or Roof rat is adequate reason to initiate management efforts addressed at eliminating the rats.

 

Management efforts should continue until all visible signs of the rats are absent. Monitoring for the detection of a new rat infestation should continue year-round.

 

IMPROVED SANITATION:

Rats are attracted by food spills, open garbage, and food stored in accessible sites. Reducing the rats' food will reduce the rat-carrying capacity of the site, as well as making lethal control programs more effective.

Pet food dishes and water dishes should not be left full overnight. Bird seed is a favorite rat food. Bird feeders should be equipped with seed catchers, or the dropped seed should be cleaned up every evening.

 

HARBORAGE REDUCTION:

Landscaping should not include thick hedges or bushes which obscure the ground. Ground covers such as ivy, which provide cover or runs for rats, should not be planted adjacent to buildings. High grass, weeds, wood piles, and construction debris should not be permitted near foundation walls. Dumpsters and outside garbage containers should sit on a paved or concrete pad. Indoors, reduce clutter in rarely-used rooms and organize storage areas.

 

• Elevate stored items, salvageable, and fire wood a MINIMUM of 18” above CLEARED ground and at LEAST 12” from walls and fences.

• Garage and crawl space areas should be cleaned; clutter eliminated and stored items elevated.

• Trees should be a MINIMUM of six feet from roofs, attic vents, eaves, and utility wires to deter crawling and jumping access.

• Ground foliage should be 18”-24” from structure and thinned from the ground.