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Swimming The brown rat is also known as the sewer rat or wharf rat. These names give us insight into a wild rat's range of territory and the demands associated with them. In the wild, the brown rat shows a tendency to colonise near a natural or human provided 'fresh' water source. A water source may be from a brook, stream, sewer network, farm animal drinking trough, or any other form of water catchment device. With water, both fresh and saltly, comes an opportunity for swimming. The brown rat is an excellent swimmer and research has shown it can swim for up to 3 days (in warm water) before it becomes exhausted. Add an ability to dive and swim underwater and you are presented with a behavioural trait that allows for a greater range of movement and opportunity...including up through a toilet. The following links display BBC Natural History Unit videos of wild brown rats demonstrating their swimming technique in still and rapidly flowing water. In the first video the rat's left front paw is tucked up into its body and remains motionless (injured or a strategy to maintain direction?) while it right front paw and rear paws are pulling and treading. The second video displays a rat in rapidly flowing water attempting to find an exit foothold. ARKive Clip 1 | ARKive Clip 2 ARKive is a 'virtual' conservation effort building audio-visual records of the world's species for the internet era.
The following is from a BBC article and displays how swimming has become an essential part of a particular harvesting technique.
Rats get taste for shellfish
A Cambridge University professor says Britain may soon face a boom in its
rat population because the rodents have learned to harvest shellfish.
Cambridge University freshwater biologist David Aldridge says the rats are
diving into a river near March, Cambridgeshire to eat mussels. Local residents have discovered piles of discarded mussel
shells in their gardens that he thinks have been left by rats. "The rat
population has already exploded in the area and will continue to explode,"
said Dr Aldridge, who works in the university's zoology department. Plentiful supply Although Dr Aldridge has not seen the rats in action
himself, local residents have reported piles of shells, in their gardens.
Some people in March have spotted rats dragging mussel shells from the
river one at a time. "The site in March has 50 mussels per square metre of
river and each mussel is 10 centimetres long. There's a lot of meat in
there, " he said. It is estimated that 30% of the mussels in a one-kilometre
stretch of river at March have been eaten by rats during the past three
years. Dr Alridge said the policy of draining rivers to prevent flooding
is possibly how the rats have learned about the new food source. Clean water |
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