"Fingerprint" identification for native frogs
Personal "fingerprint" identification for native frogs
The Department of Conservation has made a technological breakthrough that will allow the individual identification of rare Archey's frogs using a method a little like fingerprinting, Conservation Minister Chris Carter announced today.
"Archey's frogs are critically threatened. Just two populations remain but until now our efforts to save them have been hamstrung," Mr Carter said.
"To the human eye the frogs can all look the same which has made it very difficult to identify and monitor individual frogs in a population. This has meant we have struggled to answer critical questions, such as how many frogs are living at a particular site, how far do they move, how often do they feed, and how long do they live?
"The only way we have been able to identify individuals is by applying external markings to a frog's skin but that is really inappropriate for frogs because their skins are ultra-sensitive," Mr Carter said.
"Now, thanks to a technological breakthrough by Avi Holzapfel, a scientist with DOC's Waikato conservancy, we have a solution that in many respects is the frog equivalent of fingerprinting.
"A special mirrored stage has been developed on which individual frogs can be digitally photographed. The stage captures the frog from four different angles at once allowing DOC to identify and record the tiny, subtle differences in each frog's markings.
"This technology is another fantastic example of DOC 's ongoing innovation in its efforts to preserve our unique biodiversity. It has the potential to significantly advance conservation of Archey's frog, a species that really needs our help," Mr Carter said.
Dr Holzapfel said the idea of a mirrored stage had come to him after looking at many images of Archey's frogs.
"It struck me how distinct their natural markings are, and I began to explore the possibility of using these markings to identify individuals - in a similar way as is done, for example, with the tail fluke of whales."
Dr Holzapfel's original design used parts of an old broken bathroom mirror and a digital camera. Guido Palmer, a student at Waikato University's optics department, then developed this design into state of the art technology. The prototype was laboratory and field tested, and promoted with $25,000 worth of financial assistance from engineering and environmental consultancy MWH New Zealand.
"After some initial refinements the results from those pilot trials were very encouraging," Avi Holzapfel said.
"We photographed frogs on six occasions over two months, and each night found between 12 and 17 frogs. Using the photo-ID of each frog, we were able to show that, rather than finding the same frogs each night, we actually observed 47 different individuals. Some were caught only once, others were recaptured several times.
"We will now be able to answer key questions about Archey's frog that have not been answered before and these will be critical to the successful management of a unique animal."
- The "mirrored stage" and digital camera for recording and monitoring Archey's frog in the wild has been developed by the Department of Conservation Waikato with practical help from Waikato University and financial sponsorship from MWH New Zealand.
- The new technology replaces largely unreliable counting and "skin marking" techniques used in the past. Those techniques have long been considered inappropriate for a highly endangered amphibian species with a very sensitive skin.
- The frog is placed on a mirrored platform and photographed from all angles simultaneously, thereby reducing handling time and the possibility of stress. Its unique markings can then be recorded ensuring that no frog is monitored twice.
- There are only two known populations of Archey's frog remaining, one on the Coromandel and the other in Whareorino in the western King Country. The potentially lethal chytrid fungus has recently been detected in both populations, adding to the pressure on them from introduced predators.
- New Zealand has three other native frog species apart from Archey's - Hochstetter's (also found on the mainland) and two species (Hamilton's and Maud Island) found only on islands in the Marlborough Sounds. The new technology may well prove suitable for monitoring the Hamilton's and Maud Island species.
- MWH has sponsored the development and field-testing of the "frog stage".
- MWH is an international engineering, environmental, technology and management consultancy with 560 staff in New Zealand. Refer www.mwhglobal.co.nz/frogrecovery