COLIN O’DONNELL
On the front line of extinction
Five minutes. That’s what it took to save a species. Three hundred seconds of intense concentration, standing alone in complete stillness, counting each burst of birdsong in a roughly 200m area.
Since 1985, Colin O’Donnell has made an annual spring pilgrimage to South Westland’s Landsborough Valley to listen to the forest.
Using the ‘‘five-minute bird count’’ or 5MBC, developed by New Zealand conservationists in the 1970s, he was monitoring bird species in the dense beech forest.
But over time the forest began to grow silent. The distinctive scolding chatter of mō hua was fading, a warning that the species was on the verge of extinction.
The tiny yellow bird was once widespread, with large flocks dominating the foothill and valley forests of the South Island.
‘‘They used to be probably the commonest forest bird in the South Island. When I started walking up in the Hawdon Valley, in Arthur’s Pass, in the mid-80s, you’d come across flocks of up to 60 mō hua. A crazy bunch of birds weaving its way through the canopy.
‘‘They are one of the brightest forest birds we have, a fluorescent yellow colour with brown wings. They feed up and down the tree trunks. And they have this really strange tail which holds them on to the tree, it has little spikes on the end of it.
‘‘They dislodge a whole lot of moss and rotten wood. And so other birds follow them to get the [food]. They’re like the Pied Piper of the forest, the 60 mō hua might have another 100 birds following them, parakeets and fantails and tomtits making this mad cacophony.’’
But introduced predators, like stoats, drove them to this last stronghold, deeply incised into the Southern Alps. ‘‘We found each year the numbers dropped more and more. We put a ring around it, to say this is a place to watch and be concerned about.’’
By 1992, the numbers had fallen to an estimated 14 birds, and the mō hua was following the moa, laughing owl and Haast eagle into extinction.
Heavy seed falls, known as a beech ‘‘mast year’’, drew in plagues of stoats and rodents which devoured chicks in their tree cavity nests, and competed with adults for fruit and insects. ‘‘Once a rat or a stoat climbs up the tree and sticks its head in the nest hole, it just sees dinner there, a female sitting on eggs.’’
After more than two decades of trapping (traps cover about 60km of the valley) and aerial 1080 drops, O’Donnell’s five minute counts are much more challenging. Mō hua have increased 35-fold in the area.
‘‘The forest bird numbers, overall, have doubled in the time that we’ve been monitoring them up here,’’ he says. ‘‘It’s not just the mō hua increasing, it’s pretty much everything else as well. It gets hard to count them because you have seven or eight birds calling at once. So you have to really concentrate on what you’re doing.’’
Each November, O’Donnell pitches his tent on the banks of the boulder-strewn Landsborough, looking up to the Mt Dechen glacier.
He’s often joined by the other original observers: Glen Newton, Paul van Klink and Ron van Mierli. Over a couple of days, they’ll carry out counts at 175 stations, from the valley floor to its steep inclines. That’s almost 15 hours of listening.
Clipboard in hand, O’Donnell records the temperature and weather conditions, time and date, and the location of his station. On his second count of a grey, still morning, he begins rattling off the names, translating indecipherable notes into recognisable bird names. It starts with a chaffinch, and then a tū ı¯ wheezing in a nearby tree.
‘‘Our first mō hua straight over there,’’ he says, as a flash of yellow flits across the canopy. ‘‘A brown creeper that way. A silvereye. Grey warbler going now, and a bellbird. Paradise ducks flying past and a tomtit. We’ve already got that mō hua that’s calling there. That’s just a little rifleman, that real high-pitched thing down there, and a fantail – everybody’s over in that corner.
‘‘That’s good. I got six mō hua, which is pretty good anywhere in the world.’’
But O’Donnell’s auditory skills – honed over decades tramping New Zealand’s forests – extend far beyond just counting. He translates each chirp, twitter and squawk into a behaviour. ‘‘A bird doesn’t just have one call. They have a repertoire. We were just listening to the male mō hua doing territorial singing, because his female was sitting on the nest.
‘‘Then the female has a call when she comes off the nest. She’ll be off feeding for 10 minutes, and then she’ll do a different call when she’s flying back to the nest. So, even if people know what a mō hua sounds like, they might just think: ‘Oh, it’s a mō hua’. Whereas I can say: ‘Oh, there’s a male and a female there’.’’
He registers 28 – and over the entire monitoring expedition the team records 485 mō hua. ‘‘That’s really an awesome number.
You go to some forests, without predator control, and might only get six or seven birds.
‘‘This valley has got all the forest birds you would expect anywhere on the South Island that aren’t extinct. From the top predators like New Zealand falcons, to honeyeaters, bellbirds and tū ı¯, and insect-eating birds like the mō hua, the brown creeper, tomtits.
‘‘And at night, there’s morepork calling, kā kā zipping around, and kea. The full community of birds that you’d want in a valley like this. And all of them have been increasing. That’s what’s really gratifying about the project.’’
It’s a joyful interlude that gets O’Donnell out from behind his desk, at the Department of Conservation’s Christchurch office. It takes him a while to re-acclimatise. ‘‘I only hear birds calling after one of these trips, because you really have to concentrate utterly on the bird calls.’’
As principal science adviser with DOC’s Terrestrial Ecosystems and Species Unit, O’Donnell is on the front line of extinction. ‘‘I lead a programme where we try to decide which threatened species to work on first, understanding the causes of decline, and what sort of threats that we might be able to manage,’’ he says. ‘‘That’s a really big job with the resources we have.’’
The world is facing a biodiversity crisis. One million species (500,000 animals and plants and 500,000 insects) are threatened with extinction in the coming decades and centuries. Nowhere is this crisis more pronounced than in New Zealand, which has the highest proportion of threatened species in the world.
Since the arrival of humans on these shores, 79 species have been recorded as lost to extinction. It’s regularly asserted that more than 4000 native plants and animals, including kā kā pō and kiwi, are at risk of extinction.
But says O’Donnell, the death list is far higher – more than double. ‘‘On our official lists, we’ve got about 9000 species that are threatened or at risk, or that we don’t know much about, but they might be threatened. Then there’s about 1300 species on our most atrisk list. All sorts of birds, bats, fish, plants.’’
Human activity is the main cause. We use so much space and so many natural resources that other life forms are struggling to survive. Habitat destruction, climate change, overexploitation of natural resources, pollution, and invasive species are driving the decline.
‘‘Wherever we go, we displace wildlife, species, plants and so on by all the things we do,’’ he says. ‘‘We’ve cleared many of the forests and wetlands for agriculture and human use. We continue to build roads, and we continue to spread our settlements through the landscape.
‘‘We’ve also introduced pests. Predators eat our native species and cause decline that way. Browsing animals eat threatened plants, displace things and reduce the numbers.
‘‘We’ve brought weeds with us, which are encroaching on all of these habitats. And we continue to disturb species around the country just through our actions.’’
For a man who has devoted his career to conserving nature, the loss is distressing.
‘‘Biodiversity is the whole richness of life to me. It’s everything. It is essential to life in so many ways. We depend on biodiversity for our food, our economies, for enjoyment, our wellbeing.
‘‘And everything is interconnected. The plants depend on the birds and the bees and the geckos to disperse their seeds or pollinate them. There’s a million different examples.’’
But O’Donnell is driven by optimism and immense levels of patience. As well as 36 years dedicated to mō hua, he’s been running long-term research projects in Fiordland’s Eglinton Valley and studying alpine fauna – rock wrens, weta and lizards – which exist above the bushline.
‘‘A lot of the work we do is trying to prioritise what we do for a start. We look at what’s the most threatened thing that we need to work on first to at least hold the line.
‘‘But we also look at, if we work on this species, can we learn about a bunch of other species so that we can transfer that knowledge to a broader range of species.
‘‘You can do that by choosing a good flagship species to study and then apply that knowledge elsewhere.’’
Landsborough Valley is the perfect example of this approach. O’Donnell, who has a PhD in zoology from the University of Otago, first went to the West Coast to study the potential impacts of logging on forest birds.
‘‘That led to contributing to stopping logging on hundreds of thousands of acres. That was really rewarding.’’
It is one of the projects of which he is most proud. ‘‘With the West Coast stuff I got interested in the mō hua. I thought they’d be common as dirt and then found the population virtually gone.
‘‘And so we wanted to reduce that decline, obviously. But we also realised the factors that influence their survival were influencing lots of other things. We discovered more about stoats and rats being a problem and then how to control [them].
‘‘That led me to Fiordland, where there were still good numbers [of mō hua] and I started working on trialling stoat control techniques.’’
Fiordland is one of the last strongholds for native bats. For more than a quarter of a century, O’Donnell has been monitoring populations of long and short-tailed bats, and he is now a world-leading expert in the flying mammal. Pest control has also helped numbers in the remote forest colonies increase.
But intensive conservation is painstaking and expensive. DOC, councils and OSPRI at present spend more than $70m a year on pest control, and that excludes the cost of monitoring work and translocations.
‘‘We need to do this conservation work. There’s a lot of reasons to do it. One of them is that these species and ecosystems totally sustain us. So it should really be the highest priority in people’s minds.
‘‘If we don’t look after them, then we won’t have food in the future, we won’t have places to live. These species are totally essential. Without them there won’t really be any humans to speak of.’’