What is the plight of the Banks Peninsula tree weta, Hemideina ricta, the rarest tree weta in New Zealand? The Banks Peninsula Conservation Trust helped Lincoln University contact over 40 enthusiastic landowners keen to know if they had weta on their patch. The resulting Weta Watchers group has helped put out and monitor safe-houses for the weta. These “weta motels” provide a predator-proof refuge, and are easily checked, avoiding the need to damage their natural hiding places.
Weta have been knocked back by introduced predators, especially rats, mice and hedgehogs. Bush clearance has reduced and fragmented their habitat, although fallen totara and broadleaf logs provide some cover in otherwise open pasture. Locals recall seeing many more weta in the past than now.
Landowners are keen to give the weta a better chance once they realise that they are endangered – awareness and information on conserving weta and their habitat are important. An impressive number of Peninsula farmers have already fenced and covenanted areas of native bush, realising it has special value and won’t regenerate while grazed. This is good news for weta and other wildlife, and will allow populations to build, especially if introduced predators are kept in check. Weta motels on newly-protected bush are a good way to monitor resulting changes.
H. ricta is now found only from east Pigeon Bay south to the Akaroa heads. One other species, Hemideina femorata (the Canterbury tree weta) occurs on Banks Peninsula, as well as from Kaikoura to Christchurch. Although in better numbers than H. ricta, its conservation is also important. They look quite similar, but a magnifying lens can be used to count file-like ridges on the side of the abdomen – H. femorata has fewer. DNA provides another means to distinguish them. “Long-drops” will be fitted under some motels to collect frass (weta droppings) for species identification through residual DNA contained in the frass.
Interbreeding is another possible risk to the endangered H. ricta. DNA analysis will show to what extend these species interbreed, and whether their offspring are sterile.
For more on weta motels you can look here and, for a more technical treatment, here.