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'Contact logger' to record close animal encounters

An innovative device designed in New Zealand to log interactions between animals is being trialled in the United States, in a study on the spread of rabies among raccoons.

The 'contact logger' was invented by staff at Sirtrack Ltd, a subsidiary company of Landcare Research that designs and manufactures wildlife tracking equipment for use on birds and animals. These devices can be used to measure activity, mortality (indicating when an animal has died), heart rate, temperature and sound. The new contact logger acts as a proximity detector, recording when animals come within a prescribed distance of each other.

Sirtrack manager Dave Ward says the information the contact logger gathers is important for agencies wanting to know more about the spread of disease through a population.

"We have had interest from agencies concerned about the spread of Bovine Tb in badgers in the UK, and deer and possums in New Zealand. But the main driver is a team from the Max McGraw Wildlife Foundation in Illinois. Raccoons are vectors for rabies, which can also be passed on to humans. The Foundation wants data on contact between raccoons, to help construct a computer model of the expected spread of the disease into Illinois.

"We sent them 10 prototype devices which fit onto raccoon-size collars. These will show how often raccoons come within a set distance of each other.

"The devices can also be used to detect the presence or absence of animals at nest sites, dens and other places of interest, and record how often individual animals pass by fixed points."

Mr Ward says each device will broadcast a unique ID code, while simultaneously listening for others. "If another ID code is detected it means another animal has come within range. The receiving unit records the time this happened, and the ID code of the transmitting unit. The other unit is also listening, and does the same.

"We have anticipated the problem of a 'memory flood' occurring when animals den together, or come into contact with three or more other animals at once. The units are pre-programmed to cope with this. "Additionally, the devices contain a standard radio transmitter. Therefore, we can go and find the animal and retrieve its collar if we need to."

Once retrieved, the contact logger can be plugged into a computer and the data downloaded. "Further refinements are possible depending on market demand. Instead of being plugged into a computer, the loggers could transmit their proximity data by radio waves, or even via satellite."

Mr Ward says just as the prototype contact loggers were customised for the raccoon study, devices made in future will also be customised. "They will have different sizes and different battery weights, depending on the animal concerned. They will also be programmed to detect proximity at different distances, up to several hundred metres."

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