Endangered snails

Rhytida oconnori is the only critically endangered species found in the Abel Tasman and numbers were thought to be in decline.  However monitoring by DOC and Project Janszoon in 2015 found that both Powelliphanta hochstetteri and Rhytida oconnori populations are much more widespread in the Abel Tasman than initially thought.

Ruth BPowelliphanta hochstetteri - photo Ruth Bollongino

 


Rhytida oconneri

Rhytida oconnori - photo Ruth Bollongino

Radio tracking snails for the first time in NZ

Never before have the rare, carnivorous snails been studied so intensively in the Abel Tasman.

In the spring of 2016 Dr Brian Lloyd, assisted by Dr Ruth Bollongino, attached tiny radio transmitters to ten Powelliphanta hochstetteri snails near Canaan Downs to investigate their ranging behaviour and activity.  The snails in this study were from the sub-species P.h. hochstetteri, ranked as nationally endangered. They were monitored, day and night for the next 41 days.

This is the first time snails have been radio-tracked at night in New Zealand, giving a unique insight into the carnivorous land snail’s behaviour.  Results found snails are active for one or two nights and then have longer periods of inactivity, preferring to move on warm, moist nights.  Unsurprisingly they don’t travel great distances, on average just 1.32m, although one did travel 3.8m. 

Interestingly, the snails tended to move in a straight line with a slight left bias.  None went back to the same spot which indicates they are not territorial and don’t seem to have a home base.

Transmitted snail RB

A Powelliphanta snail with its transmitter - photo Ruth Bollongino