Covering climate now: A bird on the brink

If the rare NZ fairy tern manages to hang on, the future promises acidifying oceans, rising seas, more frequent severe storms, and potentially changes in prey distribution. Photo / NZ Herald

With a population of 45, the New Zealand fairy tern is at the brink of oblivion.

Climate change may nudge it over.

Our rarest breeding bird is clinging to what's left of its habitat in four breeding sites, at the bottom of the Northland Peninsula.

The delicate shorebird's precarious existence amid the shelter of sand dunes and estuaries has been made tougher by constant encroachment of development, and the nuisance of humans and our vehicles.

Their nests were already well at risk of being blasted away by high winds, or wiped out by king tides.

The last few seasons had proven devastating for their breeding, with last year just two chicks hatching, and one breeding female dying.

If they hung on, the future promised acidifying oceans, rising seas, more frequent severe storms and potential changes in prey distribution.

"They're already finding it so hard, and climate change is just going to make it worse," said Georgina Garon, a volunteer conservationist and committee member of the NZ Fairy Tern Charitable Trust.

"Food is going to become even scarcer with warmer temperatures and higher acidity in the ocean, so they're going to have to forage further and further. I think the future is going to be really bleak for them if they can't find fish in their area."

Garon has been fighting for their survival, in various roles, for the better half of a decade.

"Once I started going out and monitoring them, I just fell in love with them. Even in high winds and storms, they'll still try to get out there and find fish."

The NZ fairy tern's population already sits below 50. Photo / NZ Heral

Yet the fairy tern didn't seem to enjoy the star power of some of our native forest birds like kiwi or kōkako – perhaps, Garon thought, because we associated them with pesky red-billed seagulls, incidentally also now threatened.

In the end, it might not matter. Virtually all of New Zealand's species would be affected by more extreme conditions, transformed ecosystems, new diseases, and maybe even more disease.

Georgina Garon has been fighting for the NZ fairy tern's survival for the better half of a decade. Photo / Supplied

Some - tuatara, takahē, little spotted kiwi and Archey's frog among them - faced smaller chances of adaptation than others.

Like fairy terns and other marine birds, little blue penguins would be doubly affected as there was no refuge. With changes to prey, adults would have to work harder to provide their chicks enough energy.

The reclusive cobble skink might be soon gone just a decade after it was discovered on a tiny beach north of Westport, where its entire habitat is squeezed into one hectare.

Severe storms and higher seas could also send it to extinction.

Things are just as dire for another recently discovered skink species, the chesterfield skink.

While it's possible these creatures once lived in trees, they'd been pushed out of rough pastoral areas and into a thin strip of coastal habitat, where they faced the same predicament as the cobble skink.

As snowlines slowly climbed, pests would begin pushing above treelines, where they could kill fragile alpine species like the dainty rock wren, along with lizards and invertebrates.

The rodents that plague New Zealand's wilderness, killing millions of native birds each year, are already responding to climate change.

Last year's spring and summer brought just the kind of hotter, wetter weather we could expect from climate change.

As snowlines slowly climbed, pests would begin pushing above treelines, where they could kill fragile alpine species like the dainty rock wren. Photo / File

Under these conditions, rats in the North Island rats were starting to behaved more like they did on tropical islands – with longer breeding seasons, and bigger populations.

In our rivers, streams and lakes, freshwater plants and animals will experience everything from more intense floods and droughts to the knock-on impacts of more irrigation and new pests and weeds.

Underwater, the toll of acidified oceans could be enormous.

The decline in pH is projected to continue in line with the increase in atmospheric carbon dioxide, leading to the most rapid decrease in ocean pH in the past 50 million years.

The effect was associated with decreases in nutrients such as nitrate and phosphate in the surface ocean, where most marine organisms live.

Even small shifts in pH levels could have big consequences: mussels and paua might struggle to build their carbonate shells.

By 2100, perhaps just 25 per cent, or less, of our existing cold water coral communities will be able to sustain growth.

Garon hoped the tiny fairy tern, at least, wouldn't feature on the list of climate change's victims.

"They're on the brink of extinction, yet they are still so spirited, just trying their hardest to survive – I think their character is amazing."

This story is part of the Herald's contribution to Covering Climate Now, an international campaign by more than 170 media organisations to draw attention to the issue of climate change ahead of a United Nations summit on September 23. To read more of our coverage go to nzherald.co.nz/climate