Bream Head Reserve from Manaia

Biennial Lizard Survey

A Bream Head Trust biennial lizard survey was carried out in February 2019. Twenty one skinks were caught/observed, up from ten in the previous survey.

Full results are in the 2019 Lizard Survey Spreadsheet (Microsoft Excel Workbook, 149kB). The discussion and recommendations from the survey are reproduced below.

Discussion

Former Ranger Peter Mitchell assisted Adam Willetts with this years’ survey. The 2019 BHCT Lizard Survey returned results reasonably consistent with previous years. Unfortunately this survey observed its first rainbow skink (plague skink) near the Bream Head skink site at the summit of Te Whara. The G-minnow traps caught more skinks than the pitfall traps once again, and the catch of 9 skinks in the G-Minnows is far higher than the average catch rate of 3.43 lizards. The catch of 2 lizards in pitfall traps is just higher then the average 1.71 catch rate for pitfall trap catches. In 2019 there were a total of 21 skinks and 1 gecko observed. The 21 skinks observed is far higher than the closest record of 10 observations, and far higher then the average of 4.57 lizards observed over the period of surveying since 2011. The 21 observations were made up of 19 Bream Head skinks, 1 forest gecko and 2 ornate skinks The one gecko observed was during the survey period by Ros Cole-Baker on the Te Whara track approximately 150m due East of the Te Whara and Peach Cove Tracks intersection. The gecko startled and fell from a tree onto the track edge.The 1 gecko is consistent with the average catch/observation of geckos of 1 per survey, but far less than the 6 found in the original survey of 2011.

The finding of zero geckos in the ACO survey is less than the average catch rate of 0.5, and is lower then the best ACO observation of 2 geckos in 2015. There has not been a gecko in an ACO cover since 2015, although two gecko skins have been found in the ACO covers in this period. The finding of zero geckos during the spotlighting survey is lower than both the average observation/catch rate of 0.6 and quite lower then the highest record of 3 geckos spotlighted in 2013. There has not been a gecko spotlighted since 2013, although there was an Auckland green gecko found on the side of the Peach Cove Track in May 2018, and the forest gecko observed by Ros Cole-Baker on the 16th of February 2019. Of note also were the 4 giant centipedes and 28 Auckland tree weta found in ACO covers, and one large mecodema manaia beetle found in a pitfall trap. Of important note also is the intensive observational lizard survey work being conducted over the 2019 summer period by herpitoligist Ben Barr. Ben is observing the relationship between the Bream Head skink and the introduced rainbow (plague) skink, with the objective being to determine if the introduced skink is having a negative impact on the endemic Bream Head skink.

Recommendations

2019 was the first time the Bream Head Conservation Trust switched from an annual to bienniel survey method. All other survey components stayed the same as previous studies. This new method is more efficient for the Trust rangers and the consistent catch/observation results support that at this point in time it has no detremental effect on the survey validity. The only concern with the overall BHCT lizard survey is the fewer gecko catch/observations via ACO covers and spotlighting, however this reduction has been happening since 2013/2015, and two geckos were actually observed (by opportunistic observations) within the past two years (1 in May 2018, and 1 on 16th February 2019). Two geckos observed over 2018/19 is consistent with the combined average of ACO, spotlight, opportunistic observations of 2.125 geckos since surveying started in 2011. Therefore this biennial survey for lizards within the Bream Head Scenic Reserve should continue in its current form, with results tracked over time for comparative data to assist in the assessment of the restoration management of the reserve by the Trust.

Adam Willetts, BHCT Project manager/ranger – 17 April 2019.