The brown rat
is to be found in most parts of the world but is believed to have
originated in eastern Asia, from whence it spread partially on foot,
and partially by ship. It
came to Europe relatively late, probably around the 18th century,
but when it did it spread extremely rapidly, and is still doing so
today. Some estimates give 5 rats for every human being
on the earth.....Scary..!!. and that wherever you are, there is a
rat within 15 metres. This animal is a survivor but is mainly found
in close contact with man. Thus we find ratty in warehouses, buildings,
farms and more often than not, in roof spaces of houses. Some schools
of thought say that rats are not good climbers.. rubbish .. quite
frequently have I met these chappies in roof spaces, ideal with lots
of nice insulation to make nests with protection from the winter cold.
Then what do you know?, a quick journey down the wall cavity following
their noses, and hey presto!!, they end up in your kitchen probably
because hubby left a gap round that outlet pipe when he plumbed in
that new dishwasher...ooops!!.
In the wild brown
rats tend to stay within a restricted area, provided that it has sufficient
food, so it's territory is usually small. If food is hard to come
by a rat will travel some way from it's nest on the track of a tempting
food supply. When crops ripen in the fields, brown rats will make
journeys of 4-5 kilometres every night to find food. They always follow
the same routes, hence the term "rat runs", and these soon
become obvious running along the tops of walls in built up areas or
through long grass beside ditches in the country. Brown rats live
in small groups whose members are probably all descended from one
female. A hierarchy is established within these family groups, with
one or more dominant males. The position of the rat in the hierarchy
seems to depend upon it's weight rather than it's age. Females for
example will not mate with males that are lighter than themselves.
Each family group occupies a territory, and in areas where rat population
is high, the territorial boundaries are patrolled rigorously. Intruders
are identified by their smell and are expelled. Below is a mother
with some babies:
Brown or Norway rats
are basically nocturnal, although some individuals can be spotted
during the day in highly populated areas. It would seem that these
are low-ranking in the social structure and have been denied access
to food by the dominant rats during the night, when most activity
takes place. Their diet is extremely broad, and they will almost anything
that is edible, with a food preference for grain. They eat more meat
than the Black rat, and if they get the opportunity, they will eat
carrion and will prey on other animals. In the wild, brown rats will
eat snails, insects, crustaceans and freshwater shellfish. They also
attack nestlings and eggs of water birds, and they eat small vertebrates
such as shrews, mice and voles. In times of extreme privation, they
will even eat other rats - usually sick or weak individuals - but
this is rare.
They frequently infest
public tips, slaughterhouses, domestic dwellings, warehouses, shops,
supermarkets, in fact anywhere there is an easy meal and potential
nesting sites. If you see one running about in say a warehouse, you
will notice that it always runs along the wall/floor junctions, unless
of course you are trying to batter it to death with a shovel. This
is because rats have a sense which tells them exactly where they are,
a bit like you going into your dark bedroom and turning on the light,
you know just where the switch is. This sense is more developed in
rodents and if startled, they know exactly where their line of escape
lies. They also love and adore fat balls and grain and the types of food that you lovely ladies put out for the birds....if you do, you must make sure that the food is unable to be reached by overhanging trees/bushes or undergrowth or up the leg of a wooden bird table....etc etc.
A few interesting facts:-
- Consumption of food is approximately
30 grams per day.
- Will drink approximately
60 ml of water per day.
- The only species to occur in
sewers in the UK.
- The lady rat is only pregnant
for 3 weeks (Gestation period).
- The litter size can vary from
7 to 8
- This lady can have between 3
to 6 litters per year, depending upon food availability and harbourage.
- After a period of 10 to 12 weeks,
the babies aren't anymore, and so they breed on.
- Thank God the natural mortality
rate is about 90%.
- They also leave about 40 droppings/day....!!
think of the bill in toilet paper..
Diseases carried by brown rats:-
by all rodents.
roundworm. Initially the worm lodges in the intestines, but the
larvae may invade
the muscles to form cysts that are often resistant to drug treatment.
Rat Bite Fever...Murine
Typhus spread by lice on the animal, they die of it, but not before
have passed it on.
Jaundice(Leptospirosis). Symptoms are flu like, with a
severe persistent headache and if you think
you have been in an
area where there are rats,
then you should seek immediate medical advice. Affects the liver
Hantaviruses: Description: These are viruses (not found in the UK) that are carried by rodents and transmitted to humans when they
inhale vapours from contaminated rodent urine, saliva, or faeces. There are many strains of hantavirus. The first to be isolated (1976)
was the Hantaan virus (from the Han River in South Korea, which also gives the species its name). Hantaan virus and its related strains,
Seoul virus and Puulmala virus, cause Korean hemorrhagic fever (more correctly, "hemorrhagic fever with renal syndrome"), a condition
in which the capillaries of the circulatory system begin to leak blood. Although some people with the disease are nearly asymptomatic, in
others it can lead to shock, acute kidney failure, and, in 10% of cases, death. Hantavirus pulmonary syndrome, was identified in the
United States in 1993 and is caused by at least three strains of the virus. It is known to be carried by deer mice, white-footed mice and
cotton rats. This disease is much more deadly, causing flulike symptoms that can lead to fluid accumulation in the lungs and death.
There is no vaccination for pulmonary hantavirus. Treatment includes respiratory and hemodynamic support; the antiviral drug ribavirin
has been effective in some cases
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