Auckland university researchers have written software which enables a computer to recognise rat footprints from those of other wildlife, and tell the difference between species of rats.
"By identifying rat species we can understand patterns of invasion on predator-free islands, or detect new species entering New Zealand," biologist James Russell said.
The software can be used to read cards left on either side of an inkpad that pests walk over in tunnels placed in vulnerable sites such as predator-free islands or cargo crates.
Footprint cards are a cheap method of identifying animals, particularly ones present in low numbers, or difficult for human observers to find.
The Department of Conservation uses footprint cards but analyses them manually, and it is difficult for even experts to differentiate between species with similar-looking footprints.
Automating the footprint identification speeds up the tracking of invasive animals, and technique can be easily adapted to monitor other animals.
By developing an automated method to identify species, and extending it to any animal that leaves tracks - including reptiles and insects - researchers can help track species living in an area, said Dr Russell, who now teaches at the University of California's Berkeley campus.
Tracking tunnels will be used on Auckland's Rangitoto and Motutapu islands, where eradication programmes have started against all introduced animals.