Rats are rodents that are mostly found in urban dwellings and they constitute one of the most dreaded pests today. Although there are many species of rats, there are basically two types of rats, Rattus norvegicus; the Norway/street/common/house rats which are usually brown in color and Rattus rattus the roof rats which are black in color. The brown rats are thought to have originated from northern China and have since spread across all the countries in the continents. They are easily adaptable to any environment - the chief reason for their success in spreading - and can survive longer without water than even a camel.
Brown rats start out looking small at birth, but by 12 weeks, the average male brown rat has become bigger than a female brown rat. After birth, they get their hair coat from 7-9days and their ear canals open between 12-14 days. Even though the female starts her puberty earlier between 34-38 days as compared with the male's 39-47 days; the male testes descend between 15-50 days. Menopause for the females come in between 450-540 days. Rats grow up to 16 inches in length.
The rat’s tail is one of its most important features and one of its functions is to provide balance while climbing ropes or walking along fences and tree branches. The tail of a rat has no fur but has many blood vessels that give it a thermoregulatory function; it helps to control the rat’s temperature. When a rat is cold, its tail shrinks/constricts restricting its blood flow; the less blood that flows into the tail, the more the body conserve heat. When the rat is warm, its tail dilates/swells, allowing more blood to flow to its tail and in that way loosing heat.
Rats have only two kinds of teeth – canines and molars. The incisors which are four (two up and down) are used for gnawing and they grow throughout the life of the rat. The incisors erupt between 8-10 days. The molars are twelve (six up and down) and are used for grinding food before swallowing. The first set of molars erupt in 19 days, the second set erupt in 21 days and the remaining set erupt in 35 days.
The eyes of a rat open 12-14 days after birth and are similar to humans but they basically have smaller eyes than humans and their vision is poorer (poor vision acuity)
The brown rats are mostly burrowers. They are usually found outside the walls of homes, in gutters or under boards and in bushes. Black rats on the other hand, are mostly found in roofs, attics, and on trees like palm and cypress as they prefer an elevated habitat. They also live in tall grasses and shrubs.
Rats will feed on almost anything including carcasses of their own kind and fallen fruits but the brown rats are more omnivorous.
Rats display aggression especially when threatened and may bite, fight and chase the instigator. Amongst themselves, the stronger ones become dominant while the weaker ones are subordinate. Males mate females sequentially in order of their social dominance. Thus a subordinate male rarely gets to mount a female.
The brown rat is nocturnal, a good swimmer, and can climb high as well as burrow. They also possess metacognition, a mental ability previously found in humans and some primates.
In suitable conditions, rats can breed all year round but on average, a female rat can produce up to five litters a year - a litter usually has 6-14 rats. They mature sexually from five weeks. The gestation period is usually between 21-26 days, although 26 days is rare and the average is actually 22 days. The litter reduces in number once the female is near menopause at about 18 months of age.
One amazing fact is that a female rat can conceive immediately after giving birth because they go into heat between 10-24 hours after giving birth, this is called the postpartum estrus. Brown rats and black rats can mate but the babies rarely survive, the embryos are either reabsorbed, aborted or born dead.
The average life span of a rat is two to three years even though most die before one year. Brown rats live in hierarchical groups and the lowest in social order are the first to die when food is in short supply. If half of their population gets destroyed, they reproduce quickly to restore the population level.
Other rat removal topics to read about:
How to get rid of rats
How to trap a rat
How to kill a rat
How to remove rats in the basement
Rat damage photos
How are rats getting in
How to remove rats in a building
Rat and mouse control
Pest control for rats
Rats in the plumbing
Rat poop photographs
Rats in toilet
How to remove rats in the attic
Rat Poop vs. Mouse Poop
Biology of Black Rats
About Rats - Facts and Information
What Animals Do Rats Kill?
How To Get A Rat Out Of Your Bedroom
What If You Are Bitten By a Rat
Do Rats Bite Sleeping Babies?
Do Rats Have Bones? How Can They Fit In Such Small Holes?
Do Rats Dig Holes?
Do Rats Eat Cheese? Do They Like It?
How To Get Rats Out Of The Garage
An Analysis of Inhumane Glue Traps for Rats
Do Rats Hibernate?