Ecology: The world's most endangered birds

By Karen Baird

A black-browed albatross feeding on squid. Photo: Ben Lascelles / BirdLife International.
A black-browed albatross feeding on squid. Photo: Ben Lascelles / BirdLife International.

New Zealand is home to over a quarter of the world's seabirds, the most threatened group of birds on the planet. Forest & Bird Global Seabird Programme Advocate Karen Baird reports on the latest discussions and findings from the International Albatro

One hundred and twenty of the world's leading seabird experts gathered in Wellington recently for the fifth International Albatross and Petrel Conference. Seabirds are the most threatened group of birds in the world. More than 25 per cent of them breed in New Zealand, many of which are albatross and petrel species, so we have more to gain from the talk-fest than most.

The conference covered a huge range of issues threatening the survival of albatrosses and petrels, including fishers, introduced predators on land and climate change.

Issues surrounding migratory birds such as albatrosses and petrels need to be considered in a global context.

And as Tasmanian-based Ben Sullivan from BirdLife International pointed out, the survival of albatrosses only really became recognised as an international issue in the 1980s when global fisheries started to expand and it became clear that thousands of albatrosses every year were getting hooked and drowning from long-line fisheries.

Sullivan described the work of the Albatross Task Force and its work with fisheries to roll out mitigation methods that prevent seabirds getting caught by baited hooks. The project has been immensely successful in countries where it has been operating such as South Africa and Namibia.

Salvin's albatross, one of seven species spotted in the Cook Straight during the conference's half-day field trip. Image: Ben Lascelles, BirdLife International

New Zealand though has not had the same attention and fisheries by-catch remains a significant issue for our albatrosses and petrels. New Zealand-based French ecologist Yvan Richard gave a snapshot of commercial fisheries' impact on seabird species in New Zealand and singled-out our endemic black petrel as the species most at risk.

The urgency to remedy our inadequate by-catch mitigation strategies was underscored by Biz Bell's presentation. The Wildlife Management International ecologist described her 17-year study of black petrels on Great Barrier Island - the larger of the species' two breeding colonies.

Her tracking work shows these birds migrate to waters near Ecuador during their non-breeding season, yet sadly in both New Zealand and South America black petrels are vulnerable to fisheries' activities. She estimates the population could have declined by as much as 22 per cent. This is bad news for a species categorised by the Department of Conservation as "threatened" and highlights the need to take urgent action to ward off the threat of extinction.

One of the most the most alarming talks outlined the recent population declines of our Antipodean and Gibson's albatrosses, which nest in New Zealand's sub-Antarctic islands.

Two researchers have made the arduous journey there each summer since 1991 and gave disturbing insights into the factors that have caused a 50 per cent decline in their population. We know fisheries are responsible for some of the decline, but low nesting success suggests there are other factors involved.

Tracking data shows Gibson's and Antipodean albatrosses are now travelling much further afield than a decade earlier. Their ranges have expanded, but they are still struggling to raise a chick, which indicates lack of food could be a cause for the declining numbers.

There's still a huge amount we don't know about many species of seabirds, which is why sharing information about tracking techniques and distribution is useful.

Tracking data in particular has enabled us a much greater ability to ascertain where they go and help unravel some of the mysteries of their at sea lives and the ecosystems they depend on.

It's not always obvious why some seabirds migrate to certain areas. NIWA's Leigh Torres investigated where grey petrels go after breeding on our sub-Antarctic Antipodes Islands for the year.

Amazingly, they head to the middle of the South Pacific Ocean, apparently the middle of nowhere. Torres, using a fancy modelling system, showed that the main reason grey petrels chose this site appeared to be a mid-oceanic ridge known as the East Pacific Rise.

More work is needed to relate this to specific reasons, but I suspect it's food related, especially as the very rare Chatham Island taiko was shown at the conference to also be using this area.

Australian fishing scientist Geoff Tuck gave one of the most talked about presentations that explored how seabirds' personalities could affect the likelihood of getting caught by fisheries.

He said 'bold' and 'shy' are possible behavioural traits in albatrosses, which may help determine whether or not individuals get caught when interacting with fishing vessels. He postulated that over time the 'bold' birds could be removed from population and leaves more 'shy' birds, which are less likely to get caught.

The attending experts shared an absolute dedication to finding out more about our at-risk and often little-understood albatrosses and petrels.

Alan Tennyson from Te Papa Museum for example, mounted an expedition to discover more about the Vanuatu Petrel, a species that was found only recently to be breeding on an island in northern Vanuatu. Very little is known about the species, and its future is equally uncertain.

Besides the risk of the island's numerous steaming volcanic vents and sulphur, Tennyson and his team found cats and rats were a more insidious threat.

This international conference only happens once every four years, but the exchange of ideas is invaluable. There's still so much more we need to know about our albatrosses and petrels, especially as it's likely there are undiscovered species, particularly in the Pacific.

Only once we know the details of their location, population status and distribution can we start to address the issues that threaten the survival of these magnificent creatures.

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