Critically endangered Whenua Hou diving petrels, or kuaka in Ngāi Tahu dialect, may need greater protection from lights on vessels in seas surrounding their breeding grounds, in addition to conservation management on land.

Researchers from Te Herenga Waka—Victoria University of Wellington, the Department of Conservation, and the University of California studied these little-known taonga.

Lead author Johannes Fischer, who recently completed his PhD on these birds, says there are still plenty of mysteries surrounding them.

Whenua Hou diving petrels (Pelecanoides whenuahouensis), were once found widely in coastal dunes across southern Aotearoa New Zealand. However, invasive predators destroyed all breeding colonies except one. There are now only 194 to 208 adults at a single breeding colony in the dunes on Whenua Hou/Codfish Island, near Rakiura/Stewart Island.

Although the island has been predator-free since 2000, other terrestrial threats remain, including storms, climate change, and competition with common diving petrels, says Fischer.

Fischer says insights into all the threats affecting species across their distributions are essential for effective conservation management. Until this study, offshore threats affecting kuaka had not been studied

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The researchers tracked kuaka from Whenua Hou for three years. This allowed them to identify offshore distribution, movement, behaviour, and overlap with vessels.

“These birds travel thousands of kilometres to their non-breeding grounds, where the birds then stop flying altogether and spend months on, or under, water, becoming basically tiny ‘flying penguins’,” says Fischer.

During the non-breeding season, kuaka showed extreme aquatic behaviour and spent more than 95 percent of their time on, or under, water.

“At their non-breeding distribution, these birds appear safe from adverse interactions with marine users.

“However, their breeding distribution overlaps considerably with vessels, including fishing vessels, so there may be some issues there. For example, light pollution may cause deck strikes (birds colliding with vessels due to disorientation by artificial lights), but this needs more study.”

The researchers recommend the following to minimise deck strikes:

• alert marine users to the risks of spotlights and deck lighting
• use black-out blinds
• minimise external deck lighting
• provide protocols on treatment and release of deck-struck birds
• keep records of deck strikes (including photographs to aid identification of diving petrels)

“These recommendations could help protect these critically endangered taonga,” says Fischer.

Conversations with Papatipu Rūnaka, Fisheries New Zealand, and the fishing industry to jointly identify future conservation options at sea (managing lights on vessels), on land (keeping Whenua Hou predator-free, managing dunes, and potentially translocations), and for wider issues (for example, addressing climate change) are already under way.

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