Native lizards on the Kapiti Coast

Native lizards on the Kapiti Coast

Overview of the project: Our plan has been to monitor lizards at different sites along the Kapiti Coast. Some of these sites would have intensive pest control being undertaken, and others with minimal or no pest control. Through this project we hope to gain an understanding of whether pest control is an effective method of increasing lizard abundance on the Kapiti Coast.

Lizard surveys at QE Park, Whareroa Farm & the Escarpment Summer 2015/2016 Lizard surveys were undertaken at three different locations over the summer by EcoGecko Consultants and KCBP volunteers. Any lizards captured were measured, weighed, and photographed, so we would be able to be recognise the lizard if it was caught again on another day.

Methods used for lizard survey.

Pitfall traps

Onduline ACOs (artificial cover objects)

Closed-cell foam covers

G-minnow traps

What we found.

Queen Elizabeth Park: Two sites set up during early December, with 30 Onduline ACOs + 30 pitfall traps at each. Total of of 60 Onduline + 60 pitfall traps in operation. 5 days of trapping during late February equating to 300 checks of traps. No lizards were found. Evidence of mice in the form of burrows and droppings. Two stoats sighted.

Whareroa Farm: 60 Onduline ACOs + 60 pitfall traps set up during early December over 5 sites. 5 days of trapping during late February equating to 300 checks of traps. 30 closed-cell foam covers also set up, checked 3 times = 90 checks. One northern grass skink.

The Escarpment: A day search found 13 Northern grass skinks and 3 Raukawa geckos along the Te Araroa Track. 7 northern grass skinks caught in traps. 10 mice caught in g-minnow traps.

Species of lizards that could potentially be found on the Kapiti Coast.

Northern grass skink (Oligosoma polychroma)

Northern grass skink (Oligosoma polychroma) continued The common skink is a species-complex and is in the process of being split up. The map shows the distribution of all skinks that are part of the complex. Looking at the map, the Northern grass skink (Clade 1a) is the species that is in our region the entire lower North Island from Hawke s Bay to the Cook Strait. It lives in grasslands, scrubland, scree, under rock and in thick vegetation. It is present in at three locations (both known from previous records & in our survey) but only in large enough numbers to monitor at the Escarpment. Four records exist for QEP, all north of the Whareroa Stream. They may be able to be monitored in Whareroa Farm if we relocate the pitfall traps to the more hilly sections where there is more rank grassland in sunny places. It was very surprising to get so few of these skinks at either QEP or WF. We do not yet understand the reasons for their low abundance it may be natural or it may be due to pest numbers or historical land management/use. The habitat at these two locations today certainly could support abundant populations.

Northern grass skink (Oligosoma polychroma) continued It is potentially a suitable indicator species because of it s abundance and persistence in the presence of predatory mammals (rarer species may be locally extinct and therefore not able to be monitored unless they were repatriated). It will probably be the first species to respond numerically to pest control. This skink has been caught and counted over years at Pukerua Bay during Whitaker s skink work. These skinks can be very difficult to catch using Onduline pitfall trapping is typically used to capture them. A difficulty is being able to identify individuals they can be hard to tell apart without permanent identification marks. We are trialing a new statistical method that may overcome the need to mark any animals, by only measuring the SVL and recording the trap number.

Copper skink (Oligosoma aeneum)

Copper skink (Oligosoma aeneum) continued This is a widespread, secretive skink that lives in rough grassland, scrub, forest and sometimes boulderfields. It is only in the North Island, and potentially at all three locations, but there aren t many records as yet (there is only one record, and that is at QEP). This skink is not normally caught in pitfalls, but can be found under Onduline. They are not as hard to catch as the Northern grass skink. This skink has been caught and counted over years at Pukerua Bay during Whitaker s skink work.

Raukawa gecko (Woodworthia maculata) (previously known as the common gecko)

Raukawa gecko (Woodworthia maculata) continued At present, it appears this gecko occurs in large enough numbers to monitor at the Escarpment. Surprisingly, there are no records of this gecko on the Escarpment prior to our survey, but this is probably reflective of the lack of survey effort. It is unlikely that this species has survived the pest numbers and potentially historical land management at QEP. It may be a sparse species in WF. The best way of monitoring this species is by using Onduline left out for 3 months in spring, and checked in late summer. They are easier to catch than the skinks, but can be in high numbers (they aggregate in hiding places) so people must be ready to catch several individuals when checking Onduline. This gecko has been caught and counted over years at Pukerua Bay during Whitaker s skink work.

Ngahere gecko (Mokopirirakau sp.) (previously known as the forest gecko)

Ngahere gecko (Mokopirirakau sp.) continued This gecko has a very similar distribution to the grass skink and spotted skink Hawke s Bay to Wellington. It lives in regenerating and primary forest, and is usually found on branches, trunks and foliage. No records exist for QEP, WF or the Escarpment. It is unlikely to be at QEP, but may be recorded at WF and or the Escarpment. This is because there is more original vegetation cover at both, and considerable regenerating vegetation within gorse at WF. It is for this species and Raukawa geckos that we are using closed-cell foam covers. Foam covers have successfully detected a population response to pest control in Zealandia. We are not yet sure if the abundance, if any are present, are high enough for a monitoring programme.

Barking gecko (Naultinus punctatus) (previously known as the Wellington green gecko)

Barking gecko (Naultinus punctatus) continued This is an arboreal gecko that spends most of it s time in foliage of trees and shrubs. It is highly camouflaged and difficult to find. This is a very difficult species to monitor, because this will require skilled spotlighting work along habitat edges, and there are many variables (weather, etc) that affect results.

Spotted skink (Oligosoma lineoocellatum)

Spotted skink (Oligosoma lineoocellatum) continued This species is known to be a species-complex, so it s actually different distinct species under the one name. Looking at the map, the records of spotted skinks around Hawke s Bay to Wellington represent the local species. The others in the South Island are in the process of being split up into different species. There are no records of this species at any of the three locations, but this is typically a rare species and it may only be trappable using large pitfalls and g- minnow traps. The most likely place that it will be found is the Escarpment. This is because the Escarpment is the rockiest location, whereas the other two locations do not offer highly protective habitat for large, more vulnerable lizards from predators. This species is one where long-term pest control and habitat enhancement is most likely helpful for their survival.

Brown skink (Oligosoma zelandicum) Tony Jewell

Brown skink (Oligosoma zelandicum) continued A possible species at any of the sites, as it has a widespread distribution. Like the copper skink, it lives in rough grassland, scrub, forest and sometimes boulderfields. It may also be a good indicator species. This skink has been caught and counted over years at Pukerua Bay during Whitaker s skink work.

Ornate skink (Oligosoma ornatum)

Ornate skink (Oligosoma ornatum) continued A possible species at any of the sites. It likes rough grassland, scrub, and forest. It may also be a good indicator species. Monitoring at Zealandia has indicated they respond positively to pest control even with mice present.

Whitaker s skink (Oligosoma whitakeri) Rex McDowall

Whitaker s skink (Oligosoma whitakeri) continued This skink has been caught over several decades at Pukerua Bay, but is likely to be extinct there now as no further individuals have been trapped over the past five years. All trappable skinks were brought into captivity during the 2000 s to start a captive breeding programme for a planned translocation. The Escarpment, to our knowledge, has never been surveyed for Whitaker s skink. They are not likely to be present there, and almost certainly absent from QEP and WF. The chances of finding any on the Escarpment are extremely slim, but it s always possible if the trapping is specifically targeted for these skinks by identifying and trapping potential microsites during the right environmental conditions for their activity. The best method for detecting these skinks are pitfall trapping scree-scrub habitat during warm, moist nights in the early to mid-summer. It is thought that they are subterranean, moving under ground cover most of the time. If any are found, they would be held on capture and DOC notified so that they can be brought into the captive breeding programme. A discovery will also likely lead to further intensive surveys and trapping for the skink.

Where to from here.?

It is very disappointing to get very few lizards after the effort expended in QEP, WF and Esc. Normally, such an effort would have resulted in several dozen lizards at each study site. The reasons for such few lizards is not understood. It could be mice, it could be historical land use, it could be other predators are having a more severe effect even with the pest control operations in place. Or it could be a natural occurrence lizards just are few in number on the Kapiti Coast.

We do ask ourselves, is the trapping of higher predators cats, stoats, ferrets, weasels and rats leading to a mouse problem? Mana Island once had tuatara, robust skink, Duvaucel s gecko, all large reptiles, and all become extinct on the island the only predatory mammal present known was mice. A 1980 study documented the population collapse of McGregor s skink on Mana Island, and the recovery of that species after mice eradication. Are mice a problem? we need to find out.

Ideas for monitoring at QEP: Abandon the current design at QEP it is clearly not economical in terms of effort expended & the results. Accept that monitoring may not be feasible at QEP. Further records welcomed from public & possible short survey using day searches and night spotlighting only.

Ideas for monitoring at Whareroa Farm: Abandon the current design at WF. Relocate all pitfall traps as transects up the more hilly sections of WF. Incorporate night spotlight work to determine presence of geckos Ngahere geckos, Raukawa geckos, barking geckos.

Ideas for monitoring at the Escarpment: Focus most effort on Escarpment 2 grids of lizard traps (typical pest management without mouse control) + (pest control + mouse control) Add some lines in microsites where Whitaker s skink or spotted skinks could be found.

Ideas for volunteer training: Focus on Escarpment trapping + the new WF trap lines. Find other opportunities for volunteers to learn lizard handling skills at.