The Cost in Petrel...
by Cam Speedy and Graeme Sinclair
No matter what sort of fishing you enjoy, seabirds are an undeniable part of the fishing experience. We share the ocean with them. They show us where the fish are, they keep us company across vast expanses of ocean and they inspire us with their aeronautical skills. But they can also be a pain in the arse when they hang around the back of the boat, stealing our burley, eating our baits and lures, getting tangled in our lines and even flapping around in the boat attached to a hook!
New Zealand is the ‘seabird capital’ of the world. Our waters and offshore islands are the breeding grounds for more albatross and petrel species than any other country. But, while they breed here, many of these birds live much of their lives elsewhere.
Once, seabirds of all shapes and sizes flocked here in their hundreds of millions to breed every season in the safety of New Zealand’s pre-European forests. From the fossil record, leading experts have estimated that as many as 1.2 billion seabirds once bred in the New Zealand region.
Most of the larger species laid their single, precious egg deep in historical burrows, dug into the forest floor within large single-species or mixed colonies in the heavy bush-clad environments that were typical of New Zealand prior to man. After incubation the chick was left for long periods of time while adults flew back out to sea to fish. Some of the feeding flights of species that bred on the New Zealand mainland must have involved large distances over land, since there is clear evidence that petrels nested throughout all the main islands from the lowlands right up to the sub-alpine zone, on all the main mountain ranges, far inland – even on Mount Tongariro.
Petrels or “muttonbirds” were an important food item for early Maori who knew them as "Takoketai", “Taiko” or “Titi”. Titi harvest is still a very important cultural activity to tribes like Ngai Tahu who harvest older chicks just before they fledge from a now limited number of offshore islands during special annual forays each season. But the fact that the presence of these birds still strongly remains in the place names and oral histories of inland North Island tribes is clear evidence of how far inland these seabirds came to breed, and how recently they existed. For example, Motu-taiko Island on Lake Taupo and Titi-raupenga in Pureora Forest, relate directly to mutton bird activity at these places. There still remains physical evidence too. In the forests of the Central North Island burrow structures are still evident on the forest floor – although today most are full of possums!
The reasons why seabirds have all but disappeared from the New Zealand mainland are no surprise. Predators such as stoats, rats, cats, pigs, and dogs have been widespread for over 100 years and seabird burrows are characterised by their strong “fishy” odor. A defenseless seabird chick with only an earth burrow to protect it (from its original predatory bird enemies) would have been easy pickings for such “new” hunters.
So what has the effect of losing seabirds been to the ecology of mainland New Zealand?
The most obvious one is the loss of resources for species that came to depend on seabirds as part of their own survival. Insects would have fed on the eggshells, dead chicks and guano; predatory birds such as laughing owls, weka and kea (which still prey on Hutton’s Shearwater chicks today at Kaikoura) would all have looked forward to seabird breeding time; and the link between seabird burrows and Tuatara (our ancient dinosaurs) has long been documented. The loss of seabirds has undoubtedly played a role in the decline of many of New Zealand’s original inhabitants.