Brown Rat

Scientific Name
Rattus norvegicus
Also Known As
Norway Rat, Water Rat, Street Rat
All Major Cities of Florida
Nearly Everything
Life Expectancy
1 Year
A Floridian Brown Rat
Rount-tailed muskrat conservation status - endangered

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Brown Rats in Central Florida

The brown rat (Rattus norvegicus) is a large, burrowing rodent that thrives in urban environments like central Florida. Often confused with the roof rat (Rattus rattus), brown rats are distinguished by their stockier build, smaller ears, shorter tail, and less adept climbing ability.

As their name suggests, brown rats construct underground burrow systems and nest at ground level in basements and sewers.

This comprehensive guide provides detailed identification tips, biology facts, and prevention and control methods for brown rats in central Florida.

Read on to learn brown rat habits, reproduction, diet, health risks, signs of infestation, and professional treatment options if you suspect an infestation on your property.

Appearance and Identification

Brown rats can be distinguished from roof rats and house mice by their physical characteristics at both juvenile and adult stages

Adult Florida Brown Rat

Adult Florida Brown Rats

  • Size: Adults grow up to 16 inches (40 cm) long including the tail, weighing between 12 to 22 ounces (340 to 625 grams). Their bodies alone reach 8 to 10 inches (20 to 25 cm).
  • Tail: The tail is shorter than the body at 6 to 8 inches (15 to 20 cm) in adults. It is scaly with sparse hairs.
  • Fur: Adults have brownish-black to light brown fur on top and lighter gray fur on the underside. The fur is coarse and moderately long.
  • Head: Blunt rostrum, small eyes and ears relative to body size.
  • Feet: Shorter toes and feet less adapted for climbing compared to roof rats.
Juvenile Florida Brown Rat

Juvenile Florida Brown Rats

  • Size: Newborn brown rats are about 3 inches (7.5 cm) long and weigh around 2 ounces (55 grams). They reach around 10 inches (25 cm) long including the tail by 5-6 weeks old.
  • Fur: Juvenile fur is grayer in color compared to adults. The fur is short and soft as they grow.
  • Features: Younger brown rats have larger heads, feet, and ears proportional to their smaller body size. Their rostrum is blunt compared to the pointed adult nose.

Roof rats tend to have finer features with larger ears, pointed rostrum, longer cauda, and narrower feet better suited for climbing. Brown rats are less agile climbers compared to roof rats and house mice due to stockier anatomical features. Identifying characteristic signs like tracks, feces, burrows, and nests also aids in detection.

Maturation Rate

Young brown rats grow rapidly, reaching reproductive maturity in 3 to 4 months after birth. They are independent within a month and reach adult size by 3 months old. The average lifespan of brown rats is about 1 year. Their high fecundity allows brown rat infestations to quickly rebound after elimination efforts.

Habits and Behavior

Brown rats are nocturnal and most active during crepuscular periods at dawn and dusk. They prefer living at ground level in burrow systems. Brown rats are capable diggers and can excavate extensive tunnels leading to nest chambers. Inside structures, brown rats stay at ground level in basements, crawlspaces, and sewers.

Outdoors, brown rats dig branching burrow systems with multiple entrances and nesting chambers. They only climb when necessary. Brown rats tend to be social and live in small colonies with complex social structures.

Reproduction and Lifespan

Brown rats have a high reproductive capacity. Females can start breeding as early as 2 to 3 months old. They produce up to 7 litters per year with 6 to 12 young per litter. The gestation period ranges from 21 to 26 days.