10 July 07 A local study into NZ native bug, the Weta, has found that the bug will walk for miles to find a friendly Weta lady Bug...

Landcare Research scientists believe lust is the key reason why male giant weta walk almost three times as far as females each night. Twenty Cook Strait giant weta fitted with miniature transmitters were among 100 animals transferred into Wellington?s Karori Sanctuary in February.

Above: A weta fitted with a miniature transmitter.

The Landcare Research scientists and sanctuary staff tracked the animals for 50 days and were surprised by the distances they covered, especially the amorous males. On average, male giant weta walked 96metres per night, while females moved only 33m. The maximum distance traveled by a male weta in one night was at least 295m ? the equivalent of a human walking about 15km! It?s likely the actual distance was even further as the measurements only recorded the start and finish points, not the route taken.

This most mobile weta, Number 70, regularly walked at least 250m per night, often moving faster through dense bush than his frustrated trackers. At the end of the study he was found 1km from his original release site. ?It?s likely the males walked further as they were looking for females to mate with,? says Landcare Research scientist Dr Corinne Watts.

Weta's looking for action. Illustration by Daniel Falconer.

The study revealed a positive start for the new giant weta population in the sanctuary, with animals mating and females being seen laying eggs. Not one of the animals tracked was eaten during the study and all of the tiny 1g transmitters have been removed.

Dr Watts says the study ? the first use of transmitters to track transferred weta ? provided a valuable insight into the behaviour of the animals. ?The weta spent most of their time on the ground, walking across the leaf litter and feeding on mainly native plants but some introduced plants, such as clover and dandelion. During the day, weta would hide on the ground underneath the vegetation and were very hard to find.?

For the first two weeks of the study Dr Watts and another Landcare Research scientist Danny Thornburrow scrambled through bush each night to track the animals from dusk until as late as 4am. For the remainder of the study sanctuary staff plotted the whereabouts of each animal every day.

?While weta have been transferred before, this is the first time there has been a follow-up study of the new population. It was also a very successful use of transmitter technology. Monitoring that number of animals we would expect some transmitters to be dislodged over the 50 day period.?

It?s also the first time this particular species has been transferred from an offshore island sanctuary to a mainland site. Cook Strait giant weta became extinct on mainland New Zealand over 100 years ago. Up to four transfers are planned, with up to 450 weta being moved from Matiu/Somes and Mana Islands over four years.

Giant weta are New Zealand?s largest invertebrates (weighing up to 35g) and the flagship for insect conservation in New Zealand.

?The decline of most giant weta can probably be attributed to three major causes: predation from introduced mammals, habitat destruction, and modification of habitat by browsers,? says Dr Watts. ?Defense mechanisms such as raising and quickly flicking their legs down in the hope of ?spiking? a predator?s face, or lying on their backs to ?play? dead are of little effect and highlight just how vulnerable the weta are.?

The Landcare Research study of Wellington?s new weta population was funded by Weta Workshop via New Zealand National Parks and Conservation Foundation.

Cute little Weta illustrations by Daniel Falconer.