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Rats cause an estimated $19 billion in agricultural damage in the U.S. each year, and can transmit 35 diseases. More....

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Hartford has rats.  West Hartford has rats.  Even the Quiet Corner has rats.  The only rat-free zones on the planet are in the Arctic, Antarctic, and a few isolated islands.   

Friends who live in a rural area recently saw a rat under their bird feeder.  A rule of thumb is that there are about 25 rats for every one you see.  They were hopeful it might be an Allegheny Woodrat.  Unfortunately, native Woodrats (Neotoma magister), which are actually a type of pack rat, have not been seen in CT since the 1930’s.  Their visitor was the nasty Norway rat (Rattus norvegicus), also called the Asiatic, Common or Brown rat.  (Another species of introduced rat – the Black/Roof/Tree rat [Rattus rattus] - is not found in CT.) 

The Norway rat is not native to Norway.  It may have come here from Central Asia, in boxes of grain British mercenaries brought in during the Revolutionary War.  Once rats are introduced, adapability and fertility enable populations to explode.  They eat almost anything, animal or vegetable, alive or dead, including meat, eggs, grain, insects, plants, and even poop. (Tests conducted by Martin Schein show they prefer scrambled eggs, mac and cheese, fresh bacon grease and cooked corn.  Like me, they are not fond of raw beets.)  They usually only live about 1-3 years, but in the meantime are quite prolific.  One female can have up to 12 litters/year, with 2-22 young in each batch, and babies are ready to breed in 80-85 days.  Rats breed year round and may mate again within hours of giving birth. 

Rats have lousy vision but an acute sense of smell and hearing.  They can smell rat hormones 10 miles off.  Since they have collapsible rib cages, they can squeeze through a hole the size of a quarter. These SuperRodents can leap three feet high, sprint across utility wires, and plummet 50 feet without getting hurt.  Rats can climb concrete walls and pipes.  They are avid swimmers and yes, they really can swim through the sewers into a building through the toilet bowl. 

Rat feces v. mouse feces. Cornell University
Mouse feces are about the size of a grain of rice. Norway rat feces are about 0.5 to 1" long.

Norway rats are primarily nocturnal, but may be active in daytime too.  They live in burrows in soil or straw.  Burrows may have multiple entrances and emergency exits, which are about 2-3” wide.  They also have chambers for nesting and feeding.  Norway rats use regular routes called runs.  To see if burrows or runs are active, sprinkle flour or talc around them.  One rat cranks out about 25,000 droppings per year, which are the size of an olive pit (0.5-1” long).  In contrast, mice droppings are the size of a grain of rice.  Primary predators of rats are owls, hawks, snakes, skunks, foxes, coyotes, weasels and dogs.  Most housecats are afraid of rats.

Black and Norway rats cause an estimated $19 billion in damage to U.S. agriculture each year.  One rat can eat about 30 lbs. of grain a year, and may contaminate ten times that amount with feces, urine and hair (Pimental 1999).  They cause fires by gnawing on electric wires.  They are vectors of about 35 different diseases such as salmonellosis, typhus, rat-bite fever and bubonic plague.  Lastly, rats have caused or contributed to extinction or range reduction of hundreds of native birds, mammals, reptiles and invertebrates. Although most people want to get rid of rats, about 500,000 households keep rats as pets.  Next weeks’ column will cover options for dealing with rat infestations.

Tidbit:  Actor James Cagney never said “You dirty rat!”  The line was “…you dirty, yellow-bellied rat….”  You can watch the movie star rat Templeton in Charlotte’s Web at a free showing by the Woodstock Historical Society on Friday, October 5 at 6:30 p.m. at Palmer Hall in Woodstock.

See more info on getting rid of rats at RatRelief.com (traps, poison, repellant, exterminators, prevention, etc.)


More interesting rat facts:

  • Allegheny Woodrats: These native Woodrats have white underparts, a long furry (vs. scaly) tails and ears and eyes that are larger than the Norway Rats, which are a different species.  They are solitary rats, that live alone.  They are primarily vegetarian and mostly nocturnal.  A type of pack rat, they compulsively collect things like bits of rags, metal, bones, glass, paper, feces of other animals. They were once found in one location in western CT (Goodwin 1935), but are now extirpated (locally extinct).  Deforestation, habitat fragmentation, loss of acorns and chestnuts due to Gypsy Moths and blight respectively, and severe winters, and roundworm parasites transmitted by raccoons may have contributed to their decline. Allegheny woodrats are listed as threatened or endangered in several states.  More information on NatureServe
  • According to the U.S. Dept. of Agriculture, the second leading cause of wild animal and plant extinction is invasive species.  The first is habitat loss.
  • The Roof Rat is #80 on the Global Invasive Species Database list of 100 of the World’s Worst Invasive Alien Species.
  • Norway rats are bigger than Roof rats.
  • Rats can swim ½ mile in open water.   
  • Rat bites are very painful.  A human bite is 150 pounds per square inch (psi), dog 1000 psi, rat 7000 psi, according to Bell Labs.
  • Fleas actually transmit the plague, but their favored host is a rat.
  • A poultry farm may have one rat for every five chickens.
  • Rats can communicate ultrasonically.
  • An estimated 500,000 households have pet rats (albino or hooded Norway rat relatives).  Teddy Roosevelt’s children had a pet piebald rat named Jonathan.  Roosevelt also owned a rat terrier. Owners report that pet rats are intelligent and affectionate. They are calmer, and less likely to bite than regular rats.   Norway rats are smarter, more sociable and less nocturnal than Black Rats, which is why they were used to breed pet rats.
  • Despite being common on ships and in wharfs, Black rats are not good swimmers, but they are strong climbers and are acrobatic. They do better in tropical climates.  They hang out in trees, and  nest in bunches of leaves and twigs. Black rats came to the U.S. before the Norway rat, probably with early colonists in Jamestown in 1609. They have caused catastrophic losses and extinction of many species of wildlife, especially on islands like Hawaii and New Zealand.
  • The traditional mouse trap was invented by Hiram Maxim, who is also responsible for the Maxim machine gun.
  • A young Norway rat is about the same size as an adult house mouse, but has a scaly tail, larger feet, and small ears and eyes.  An adult is about 16” long and weighs about a pound. Source.
  • Rats are a primary host of the disease Leptospirosis, a relatively rare bacterial disease.
  • Twenty rat skulls have been found in pellets taken from the nesting site of a single pair of barn owls. Source
  • 20 things you didn’t know about rats.
  • Jacko, a 13-pound bull terrier, set the record during a rat baiting contest in 1862 when he killed 100 rats in 5 minutes, 28 seconds.
  • In traditional Chinese culture, the rat is one of the 12 zodiac signs.  Source
  • Rat testicles are 2x the size of those of a 400 lb. gorilla.
  • Rats are developing resistance to some commonly used anticoagulant poisons.
  • Rat meat is sometimes eaten in the Philippines, where is it called “star’ meat.
  • Roosevelt also owned a rat terrier.
  • The film Indiana Jones and the Final Crusade used more than a thousand live and puppet and mechanical rats.
  • The International Rice Research Institute estimates that the amount of rice lost to rats in nine East Asia countries could meet the caloric needs of up to 362 million people.
  • Gambian giant pouch rats have invaded the Florida Keys. They can weigh up to 9 lbs., and can carry diseases like monkey pox.
  • Lab rats used for research are bred from albino strains of the Norway Rat. 

Links and References:


Originally published in the Villager newspapers on September 21, 2007


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