NZ native seabirds have their safety preserved on pest-free lands. Supplied by Forest & Bird
From the distance they came: dark streams turned into rivers of tens of thousands of silhouetted seabirds in the twilight.
Together they flew as a great vortex around the top of nearby Little Mangere Island and suddenly — all at once — they scattered and all torpedoed into the bush. We ducked and dived trying not to get hit by incoming birds.
The shrill sounds of thousands of seabirds filled the air. Then the ground was covered in birds that clumsily waddled round to find their burrows. These birds don't have nests made of sticks and grass but have burrows like rabbits.
This was a common summer scene across primeval Aotearoa in the time before rats, possums, cats, stoats, dogs, pigs and people.
About half of our native birds didn't live in the forests, but spent most of their lives at sea. Why? Because the country is a string of islands poking out of a vast ocean and these birds needed land only to lay eggs and to raise chicks.
By day millions and millions of seabirds fed far at sea on plankton, squid and fish. They returned to land at sunset to vomit their catch into the mouths of their hungry chicks.
Modern scientists now describe these birds as "ecosystem engineers" that fed the greatest cycling of nutrients from the ocean to the land on Earth. The enrichment from the ocean made the native rainforests on land burst with life from trees to bats to birds to bugs.
This is the ancient fertiliser on which our original agriculture was built.
And what are these weird burrowing birds? These ones were titi, also called muttonbirds or sooty shearwaters. But also on this pest-free island were also lots of other native seabirds I'd never heard of, like broad-billed prions and storm petrels.
There were so many birds you had to shuffle your feet along for a midnight toilet stop or you would step on them.
Titi leave these shores in autumn to fly and feed off the coast of California, Japan or Alaska and come back to the same spots here to raise chicks — a phenomenal journey that Polynesian ocean voyagers would have incorporated into their navigation matauranga, or knowledge.
Seabirds, including titi, once existed a long way inland. Maori place names from the flanks of Mt Ruapehu, deep within Te Urewera and elsewhere are named after titi and are ghosts of the birds' historical flight paths and nesting colonies.
Seabirds, including titi, literally made burrows from sand dune to mountain tops in their multimillions.
Today, across the main islands, titi have been wiped out by feral cats, rats, mustelids, feral pigs, dogs and people. Fortunately, some large nesting colonies remain on pest-free islands where you may be lucky enough to experience them.
Within three years of Ahuahu/Great Mercury Island (off Coromandel) becoming pest-free in 2014 , seabirds began returning and are also starting to turn up on mainland pest-free areas such as Tawharanui and Shakespear Regional Parks.
This is a glimmer of what a pest-free future can allow. The moral of the story is that if we get rid of introduced pests, nature knows what to do.
Let's make it safe for titi to return.
Some 3 million sooty shearwaters, or titi. Photo / Dave Hansford.
Each evening, some 3 million sooty shearwaters, or titi, return to their burrows on the Snares Islands after feeding trips that can take them to the edge of the Antarctic sea ice. After circling the island to get their bearings, they crash land into the treetops before tumbling through the branches to the ground.
