Conservation Flagships

We are working with Landcare Research and the Ministry of Science & Innovation on developing long-term lizard monitoring methods, and undertaking actual monitoring on-the-ground of several lizard populations in biodiversity sanctuaries across New Zealand. The intention is to develop the necessary tools and techniques to demonstrate lizard population responses to biodiversity management. We are also following up a translocation of Duvaucel's gecko (Hoplodactylus duvaucelii) on an offshore island to measure population establishment and growth since release.

Biodiversity Sanctuaries

Our work in this section represents Research Strand One (developing tools and techniques, and measuring responses in biodiversity sanctuaries).

In establishing long term lizard monitoring programmes in biodiversity sanctuaries, we have identified the following requirements:

• Ease of monitoring set-up (sampling units quick to set up, efforts can be standardised at all sites, and at future new sites).
• It is quick to check many traps or artificial refugia per session, to enable single-day sampling sessions conducted repeatedly over the course of a year.
• It is simple for non-expert project staff and volunteers to count/process animals if/when required.
• As lizards exhibit detection probabilities less than 1, there is a requirement to incorporate some form of monitoring methods which require: (a) increasing the number of animals caught per year by repeated sampling of an increased number of sampling units per replicate; and, (b) using various modelling methods that account for imperfect detection to compare counts and estimates over time.

Study sites

The selected study locations are Zealandia Wildlife Sanctuary, Windy Hill Pest Management Area and Boundary Stream Mainland Island.

Windy Hill Sanctuary. This is a large (620 hectare) mammalian-trapped ecosystem restoration project on Great Barrier Island. Mammal control was initially conducted using trap stations in a 100 x 25 m grid (1999-2000), and has now switched to poison bait stations since 2009. The only predatory mammal species on Great Barrier Island are the ship rat, kiore and mouse. Intensive mammal control has occurred since 1999, with occasional but suppressed irruptions of rat or mouse populations in autumn.

Boundary Stream Mainland Island. Boundary Stream Mainland Island (BSMI) is a very large mammalian-trapped ecosystem restoration project near Tutira, Napier. Mammal control has typically been conducted using poison bait stations in a 50 x 50 m grid. Intensive mammal control has occurred since 1996, with occasional but suppressed irruptions of rat or mouse populations in autumn).

Zealandia Wildlife Sanctuary. Zealandia is a large (230 ha) invasive mammalian-proof fenced ecosystem restoration project in Wellington. The forest consists of mixed regenerating native and exotic species following fire and agriculture in the past. Intensive control and removal of all introduced mammalian predators has occurred since 1994 using a pest-proof fence surrounding the sanctuary. Mice remain the only invasive mammal species within the sanctuary (R. Empson, pers. comm.).

Similar work is being done in partnership with Auckland Council and Bioresearches NZ Ltd. See here for information.

In all of the study sites, we have been able to demonstrate some population responses to biodiversity management. At present, we are still halfway through our research with two more full seasons of field work to go. Therefore, our results are not yet released, but please discuss with us if you are interested in seeing our preliminary work.

Duvaucel's gecko on Mana Island

Duvaucel´s gecko (Hoplodactylus duvaucelii) are our largest living gecko (320 mm long, 118 g in weight). They have a very slow life history (living up to 50+ years, become mature at 6-7 years, and have a low annual reproductive output of 1.12 young/female/year. Unfortunately, such life history and other factors has meant that this species has become extinct on the NZ mainland. This research strand involves the follow-up of a translocated population to Mana Island. In 1998, 40 Duvaucel´s gecko were released on this island from the North Brother Island. Ten were adult males, 20 were adult females, and 10 were subadults. Prior to the Conservation Flagships programme, only 26 geckos had been captured or seen in the 11 years since the release (1998-2008)

Our research aims to answer the following questions:

• Founder animal survival 11-15 years post-release.
• Population size and extinction probabilities.
• Population demography.
• Individual condition (size, body condition, parasite loads).

To date, we have now found 99 individual geckos over 2009-2011, with a minimum of 25% of the original founder animals surviving to today. However, the population now consists of 21% of juveniles, which is evidence for recruitment. We still have two more full seasons to run on this project before we can publish the results.