Conserving the Archey's frog - a rare Aotearoa amphibian

Conservation is at the very heart of Auckland Zoo, it’s why we get up in the morning, it’s what we’re about and it takes many forms; from veterinary work to breed-for-release programmes and a global network of partnerships that conserve wildlife and wild places – we call this our Wild Work. In this story we’re shining a light on just one of several conservation fieldwork projects that we lend our skills to in Aotearoa.

Every year when spring comes around our ectotherm keepers prepare their field kits for what will be, all told, more than a month of hard slog in the field; strapping on their boots and wet-weather gear, shouldering their rucksacks and going bush for 4-5 weeks to gather data on the tiny and elusive Leiopelma archeyi, Archey’s frog.

Aotearoa’s tiniest frog, Leiopelma archeyi is just a few centimetres long, a master of camouflage with brown and green markings that blend so well into the forest floor, and nocturnal to boot. This means our conservationists require plenty of patience and skill to seek them out.

Getting boots-dirty-deep in conservation is what our staff love to do and over the past eight years we’ve been lending our skills to the Archey’s frog recovery programme. Working alongside our partners at the Frog Recovery Group and Department of Conservation (DOC) we undertake annual surveys for this rare endemic amphibian. Number #1 on the list of Evolutionarily Distinct and Globally Endangered (EDGE) species compiled by the Zoological Society of London, and with a threat status in New Zealand of ‘At Risk – Declining’, raising awareness for this species and the work of the Zoo and our partners, is so important.

Named after a seminal figure in Auckland’s history, this species takes its name from Sir Gilbert Edward Archey (1890–1974), a zoologist and ethnologist who served as the director of Auckland Museum for over four decades and made significant contributions to New Zealand’s arts and natural sciences during this time. He was a prolific writer, publishing studies on marine crayfish, New Zealand centipedes, the extinct moa and the Hochstetter's frog, a relative of Leiopelma archeyi and the reason Archey’s frog was named in his honour.  

Including Archey’s frog, there are just three remaining species of endemic New Zealand frogs, all within the family Leiopelmatidae. These primitive frogs have changed little in the last 200 million years, earning them the title of “living fossil.” First described as a separate species in 1942, their original distribution is poorly known. Rats and other introduced predators remain one of the frogs’ biggest threats, which is why pest control (via biodegradeable 1080, bait stations and trapping) is so important in the strongholds where they remain. But for any species to thrive there must also be sufficient food and shelter to meet their requirements. As a terrestrial and highly sedentary frog (it doesn’t move very much and never very far), found only in the dark, damp, moss-filled forests of our North Island hills, pigs, deer and feral goats also pose a threat to this habitat and therefore ultimately to their survival.

So where does a species this special live? There are only two geographically isolated pockets left in Aotearoa where Archey’s frogs are naturally found – in Whareorino and in the Coromandel Peninsula. In 2017 Auckland Zoo helped to translocate sixty frogs to a third location in Pureora Forest as part of the recovery programme for the species. A previous translocation was made in 2006 to protect them from chytrid fungus – an infectious, sporadic disease that affects amphibians worldwide and which had made its way to New Zealand, and this second ‘top-up’ was to introduce further bloodlines (genetics) to strengthen the population as it grows and establishes. 

Waiting until the sun sinks below the horizon (generally 8pm this time of year) the team set off for the survey site, approximately an hours’ walk from the DOC hut where they’ve left their sleeping bags and provisions. Arriving at the survey site, they quickly get to work searching for emergent frogs (those that have come out from hiding – this way we don’t need to disturb their fragile habitat) within a grid system of 10x10m (100 m2) that is surveyed for four consecutive nights. When asked how they step to avoid disturbing any tiny frogs at their feet, ectotherm keeper Emily says, “heading to the field site is a slow process, the track ahead must be scouted and any frog in our path gently relocated. At the field sites we are often working on our hands and knees, carefully clearing leaf litter before we put any weight down. With good reason too, the smallest juvenile frogs we find are barely 1cm long and very delicate!”.  

Pre and post search our conservationists will track and record weather data using a ‘Kestrel’ weather meter (a handheld device with anemometers that can measure wind speed, humidity and temperature) as weather conditions play a crucial role in whether these secretive frogs will emerge. Thankfully for this trip conditions were perfect, and each visible frog is collected and carefully placed in a reusable breathable baggy to be examined back at the DOC hut. 

It’s here that the team will weigh, measure and identify each frog by their markings, and will take a photographic record via a clever camera set up. Each frog is momentarily placed on a table with angled mirrors surrounding them, these will ensure that one photograph will capture all sides of the frog at once – the upper lip, the sides of their face and the top surface of their body. All data collected from this will be added to an extensive data set, built up over 10 years of these surveys, which paints a bigger picture of their population size and stability, under different predator control regimes. All told the search that started at 8pm at night will wrap up at 3-4 am in the morning and end with each frog delicately placed back exactly where they were found – disturbing nothing in this complex ecosystem and leaving only very careful footprints.

What many people don’t know, is that the skills learned and honed in good modern zoos are also valuable for conservation work like this in the field. Knowledge of the correct way to observe, handle, breed and adequately care for a species can contribute greatly to many species’ recovery programmes. Auckland Zoo has been running a breeding research programme for Archey’s frogs for several years. As the only institution to house this unique frog, our staff observation on their behaviour can be invaluable, and perfecting their husbandry (animal care) so that they reproduce successfully and repeatedly in our care provides additional understanding of their ecology and provides another essential tool in the conservation toolbox.