Detection of caged and free-ranging Norway rats Rattus norvegicus by a rodent sniffing dog on Browns Island, Auckland, New Zealand

  • Published source details Shapira I., Buchanan F. & Brunton D.H. (2011) Detection of caged and free-ranging Norway rats Rattus norvegicus by a rodent sniffing dog on Browns Island, Auckland, New Zealand. Conservation Evidence, 8, 38-42.


Campaigns to eradicate introduced rats (Rattus spp.) from small islands are very successful; however, reinvasions on rat-free islands continue to be a major concern. In New Zealand, rodent sniffing dogs are employed to detect suspected rat incursions. The ability to detect and catch a known free-ranging rat on a rat-free island has previously been proven only once and never been experimentally tested. This study tested the ability of a rodent sniffing dog to detect a free-ranging Norway rat R. norvegicus and four caged albino laboratory rats (R. norvegicus) on rodent-free Browns Island. A male Norway rat fitted with a GPS/VHF transmitter was released on the island as part of a trial to test the ability to detect its presence using caged 'lure' rats. A failure to detect any signal from the transmitter forced us to bring in a trained rodent sniffing dog to locate the rat. In a systematic search of the island, the dog found three of the four caged rats, and through air sniffing downwind it was able to track and catch the wild rat from a distance of approximately 170 m. This is one of the very few times that a rodent sniffing dog has been tested in a realistic scenario in which there was a confirmed free-ranging rat on an otherwise rodent-free island. The successful detection and capture indicates that trained sniffing dogs can contribute to the detection of rat incursions on island sanctuaries and assist in rat control.

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