Kauri snails/pupurangi (Paryphanta spp.) belong to the group of northern giant land snails, which contains some of New Zealand's largest snails.
There are two species of kauri snail:
- Paryphanta busbyi – up to 79 mm shell diameter, distribution from Kaitaia south (Northland only)
- Paryphanta watti – up to 62 mm shell diameter, distribution: northern Northland (Te Paki)
These giants were once widespread in Northland before human settlement. Many of them are now endangered or threatened, and inhabit a more restricted area of Northland and the islands offshore.
Watch a Meet the Locals video about kauri snail.
- Giant snails may live to 20 years or more.
- Mating appears to be triggered by climatic conditions, such as rainfall, and can last for 10 hours or more.
- Snail hatchlings spend an unknown period living in trees and shrubs up to 6 metres above the ground.
- The kauri snail is carnivorous and cannibalistic. Its diet consists of earthworms, insects, insect larvae, and snails.
- Kauri snails are also highly mobile, and have been known to move 10 metres in 2 weeks.
Kauri snails inhabit moist areas of forest and native scrub. They live in areas of high soil fertility and abundant earthworms.
The causes of decline for kauri snails include:
- Habitat destruction – caused by humans
- Habitat modification – caused by domestic and feral grazers, including horses and cows
- Predation – by introduced animals, including rats and pigs
- Collection of live animals for their shells may once have had an effect on population size.
1080 poison helps native snails
Possums cause massive problems for New Zealand's native species. The periodic use of the biodegradable poison 1080 to kill possums has reversed the decline in snail populations.
Past conservation efforts
Management of priority kauri snail colonies has been carried out since the early 1980s. Most of this management has consisted of poisoning rodents, enhancement planting, fencing colonies, and stock control. These actions have successfully allowed some species of kauri snails to recover from near extinction to colonies of some hundreds.
Translocations of kauri snails have led to the establishment of populations at Awhita Peninsula, Kaimai Ranges, Waitakere Ranges, and Warkworth. Captive breeding has so far resulted in limited success.
Research has also been conducted on different aspects of snail ecology.
Transponder being attached to kauri snail
Recovery Plan in action
The first Department of Conservation Giant Land Snail Recovery Plan was approved in 1995 and is currently being updated. The new plan sets in place a series of steps that will promote the recovery of the snails. It also outlines different management options and a work plan.
The long-term goal of this recovery plan is:
'To preserve and enhance populations of all Placostylus and Paryphanta species, and Rhytidarex buddlei in their natural range. The emphasis is to direct management towards the most genetically and morphologically distinct and viable populations.'
Goals for the term of the plan:
- To encourage and support public and community protection of northern giant land snails and their habitat throughout the term of this plan.
- To secure representative populations of distinct taxa.
- To conduct research required for effective management.
You can help
These are some of the things you can do to help if you have giant land snails on your property:
- Fence off areas of bush where the snails are present. This will stop stock from trampling and crushing them.
- Control rodents, as they prey on juvenile snails. Snail populations greatly benefit from rodent control.
- Control pigs. They are also a predator, and eat adult snails as well as damaging snail habitat through rooting.
DOC welcomes any comments or suggestions you may have about the conservation of giant snails. These can be directed to the recovery group via any DOC office.