Recently I was lucky enough to spend a week on a small island in the outer Marlborough Sounds searching for and counting the very rare Hamilton’s Frog with Biz Bell from Wildlife Management International. Not only is it considered one of the most primitive frogs in existence, its also one of the world’s rarest with about 300 individuals living on a small patch of land on Stephen’s Island. As a safety measure a population of frogs was established on another island nearby.
To say I was excited as the boat left Pelorus Sound is a massive understatement. I’ve been on offshore islands a few times before, but never for a whole week and never with a conservation expert like Biz Bell. Although the quarantine at Department Of Conservation headquarters in Havelock on our way out is a painstakingly slow process it definitely added the excitement.
When we land on Nukuwaiata Island everything is moved in stages because of the heavy generator. The first challenge is a steep cliff come waterfall that we had to scale with our gear. Once on the island proper we pile our gear at the head of a stream beside the scattered feathers of a shining cuckoo, the victim of the resident falcon family. The final leg takes us up and over a ridge of regenerating bush to the hut.
Because Hamilton’s frogs are nocturnal it was pointless heading off to the frog spot before sunset. Most nights after dinner I’d sit on the deck listening to the last calls from the Bellbirds and Yellow Crowned Kakariki watching the clouds fade to black. Defying logic I’d strip down to shorts and a t-shirt, shivering for about 30 seconds before we made our way north up a steep hill. Unfortunately for one resident penguin his burrow was right next to the only spot we could get cellphone coverage, so every night for 15 minutes we’d hear him grumbling next to us while we made calls and checked facebook.
The walk felt really slow on the first night, with the ground was still wet from the previous days rain. As the week went on the track dried out and we got to know it better allowing us to zoom through the hour long walk. Seeing Morepork, Little Blue Penguins, Weta (cave, tree, ground) and large spiders was a nightly occurrence.
When we arrive at the frog spot everything changes. We don’t walk mindlessly, we check the ground before we step anywhere, careful not to tumble any rocks. At the frog hut we lay white sheets on the ground in case any frogs take exception to being weighed, measured and photographed and try to jump away. As soon as we stopped I’d balance on a raised plank and put on my warmest clothes so the slow pace of crawling didn’t chill me down. We’d put on vinyl gloves and fill our pockets with containers for the frogs. Each container has a number and a matching numbered peg so that the frog can be returned to the exact spot in the grid where it was caught.
It may seem over the top to return the frog to exactly where it was caught but these frogs are creatures of habit in the extreme. On Stephens Island its not uncommon to catch a frog in the same spot it was caught 10 years ago.
On the 2015 trip no frogs were seen for the first 5 nights. As I began the crawl my hopes weren’t high, but it only took a few minutes before I heard Biz shout “got ya” and then almost straight after that I looked down and there was a big golden Hamilton’s Frog sitting in a crack between two rocks. I paused half worried I’d grab it too hard and squish it but also worried it would make like a crayfish and shoot back into its hole. I extended my hand, cupped over it and before I knew it I had my first frog! Its a pretty amazing feeling to be holding the world’s rarest frog in your hand – I don’t think I’ll ever forget it.
Not only are these frogs exceptionally rare, they’re also very primitive and strange. For example they have an extra vertebrate (9), the remains of tail muscles in adult frogs and an incredibly long lifespan (20+ years). Unlike most frogs you’ve probably seen these guys don’t spend any of their life cycle in water, they prefer damp rocky forest. Because of this they have fingers with no webbing or pads like most other frogs (check out the photo below of one in kiekie to see what I mean).
Due to the high humidity and moist ground the frogs were out en-mass on the first few nights. We managed 16 the first night and 14 the next. Because of the very real risk of chytrid fungus each frog got its own container (which had to be thoroughly washed the next morning) and every time we caught one we had to change gloves.
Being a night owl the frog counting suited me perfectly, we’d usually arrive back sometime after midnight and wake up whenever we felt like it the next morning. Some days I went exploring and others I spent sitting in a clearing watching parakeets feed.
On the two days we had to set and retrieve pest monitoring tunnels we traversed the main spine of the island. On the ridge we were mostly walking through head high forest but occasionally there’d be an amazing view down the massive cliffs to the sea below. The cliffs are covered in a tightly woven mixture of cook strait kowhai, melicytus and flax. We found the best viewing spots were the ones seabirds had been using. In a couple of these clearings the very rare Cook’s Scurvy Grass was growing.
Another highlight of the ridge line was the old maori middens and fortifications. Usually the easiest indicator we were near a maori site was a large area that had been levelled totally flat. On the edges of the flattened areas Rengarenga lily would be growing in dense hedges. Although native to New Zealand, it was introduced to much of the lower North and upper South Islands by early maori.
As if by pure luck on our last night on the island Biz stumbled upon a very large mill stone. I’ve seen a fair few maori artifacts in museums and private collections but there is something really special about seeing one perfectly intact in-situ. What an awesome ending to the most amazing (rain free) week!. Fortunately for the frogs it looks like good news too. They seem to have settled into their new home and are slowly expanding their range. Hopefully I’ll live to see the day when they number in the thousands not the hundreds!
Be sure to check out my post on frog counting on Maud Island in a few weeks time.
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