Individual study: Conservation of a rare coastal moth Notoreas sp. and its coastal herbfield habitat, Taranaki, New Zealand
Sinclair L. (2002) Distribution and conservation requirements of Notoreas sp., an unnamed Geometrid moth on the Taranaki coast, North Island, New Zealand. New Zealand Journal of Zoology, 29, 311-322
Notoreas (Geometridae) is an endemic genus of brightly coloured, day-flying moth. There are alpine and coastal species, many of which are undescribed and facing threats from habitat loss. The unnamed species on the Taranaki coast (West Coast, North Island) was thought to have undergone severe declines due to habitat loss and fragmentation primarily through cattle farming and weed encroachment. Caterpillars feed exclusively on a prostrate species of Pimelea (also unnamed and restricted in range), a shrub that grows amongst coastal turfs. Surveys and monitoring were required to establish the distribution and conservation status of this lowland coastal Notoreas and its habitat in order to initiate a conservation management programme.
Survey area: The south Taranaki coastline was surveyed to locate patches of suitable Notoreas moth habitat in 1996-1997. Local land owners were approached to obtain access to the land and pave the way for future work. Land was owned by farmers, by the local Council, or in Maori co-ownership.
Habitat & moth distribution: During surveys, size of apparently suitable habitat patches, and distances between nearest patches were estimated to see whether presence of Notoreas moths was related to patch size, and distance to potential source populations - this would influence location and creation of new patches, i.e. habitat restoration. Threats (see below) to each habitat patch were recorded, these being factors that had the potential to reduce, or had already reduced patch size. To determine the presence of moths, several of the habitat patches were visited during the flight seasons (September to November and February to April) from 1996-2000.
Threats: Typically for the area, invasive plants had affected many habitat patches including two that were set aside the 1980s specifically to conserve the moth. These were smothered with introduced grasses, and other introduced plants including gorse Ulex and lupin Lupinus, or had been destroyed by cattle trampling. However, in a few cases the cattle trampling had disturbed the sites just enough for Pimelea to re-colonise. Fencing of patches to exclude stock was a joint initiative between land owners and the Department of Conservation. Patch restoration began in 2002 on a small scale with hand weeding (removing non-native species) and herbicide trials for weed control. Advocacy for weed control involved 'field visits', and publishing a guide to the plants of the herbfield so that volunteer weeders could be involved in retaining their endemic, local flora.
Habitat patches: A total of 47 what appeared to be apparently suitable patches of habitat were located, and Notoreas moths were detected in 24 of these. Patch distribution was clumped, and patch size and distance to nearest inhabited patch seemed the best indicators of patch use by moths. Some seemingly suitable habitat patches were never occupied by moths. It was decided to concentrate restoration effort on patches of habitat, rather than gauge moth use of the habitats since the latter was impossible to define given that moth occupancy was variable. Conserving large and/or occupied patches seemed the best approach as moths appeared to use patches in a shifting mosaic pattern and conserving patches based solely on their presence would only provide a temporary conservation measure.
Ongoing work: Several of the larger, more easily accessible habitat patches are still undergoing active management to control weeds and maintain the native flora. In most of these areas moths are flourishing. The Council has agreed to plant displays of Pimelea for education purposes. Future restoration plans include growing the shrub at a local nursery (for transplanting into the wild) in conjunction with a handout on Notoreas and information on species of other rare and endangered herbs of the Taranaki coast. The relationships with the landowners requires consistent maintenance, but setting aside time for this is essential and intrinsic for project success.
For further details see: http://www.doc.govt.nz/Publications/004~Science-and-Research/Science-for-Conservation/PDF/sfc136.pdf
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