There are people that like rats. Their ‘liking’ may well be conditional on some important factors other than a general liking for the species though. For example, if the rat is tame and has a name like Sebastian, then it’s fine. However, rats (note the use of the plural here!) that have forced entry into your home and spend their nights running up and down your loft are a different matter. And this is the thin end of the wedge of the rat problem; the cost of rat damage to buildings and crops in the UK farming industry alone is estimated to be around £20 million a year.

So obviously many people want to control the rat population effectively, but they don’t necessarily want to cause them harm, they just want them to go away. A group at the University of Liverpool in the UK are to set up a £4.7 million programme to look into humane methods of getting rid of rats using nothing more harmful than smells.

This is not quite as odd as it first sounds because smell is an incredibly important sense for rats, and scent signals are a major method of communication between them. These signals are left by urine markings; rats leave drops of urine on the ground, on objects and even on other rats.

The scent from this urine can tell rats some amazing details about the rat that left the signal. This would include things like the individual identity of the rat, its species and sex, even its age, sexual availability and current stress level.

Studies done so far have shown that some markings deter rats, while others attract them. Getting the right signal is clearly going to be an important part of the programme!

If it works this would clearly be much more humane than the current favoured method of control, poison.

Rat poisons, such as warfarin and its modern equivalents, work by causing the rats to bleed to death. They do this by blocking the vitamin K cycle which has the effect of halting the production of a few key proteins that are used in blood clotting. They also affect the capillaries, making them permeable to blood. This means that they will no longer hold  blood, again causing internal bleeding.

This doesn’t sound very nice, and in fact humans that have experienced warfarin poisoning suffer pain that is described as moderate to severe. Not such a surprise when you think that they will be bleeding into muscles and joints.

Getting a more humane method of control is just one aspect here. It is also important to get a more effective method. Rats cause huge amounts of damage to food resources around the world and with our rapidly growing population the efficiency of food production is going to be increasingly important.

It is an interesting approach, using the subtleties of animal behaviour to control rats rather than the sledge-hammer approach offered by the traditional methods.  Time will tell whether it works or not but either way I’m sure that, if they understood, the world’s 5 billion rats would be in full support of this programme.

See the original article at Scientists to use scent to control destructive rodent behaviour