The Hutton’s shearwater/Kaikōura tītī is an endangered seabird endemic to Kaikōura. The species is renowned as being the only alpine breeding seabird in the world, breeding high in the Seaward Kaikōura Ranges at elevations of 1,200 to 1,800 m. The Hutton’s shearwater is one of the few pelagic seabirds to solely breed on Aotearoa’s mainland.

When Hutton’s shearwater colonies were rediscovered in 1964, there were eight colonies remaining. At least ten colonies formerly existed in both the Seaward Kaikōura and Inland Kaikōura Ranges; and there is evidence that the species may have bred beyond these mountain ranges.

Today only two remnant breeding colonies remain in the Seaward Kaikōura Ranges, on conservation land in the headwaters of the Kowhai River and on private land at Shearwater Stream. An insurance colony was established with translocated chicks within a predator-proof enclosure on the Kaikōura Peninsula.

Threats

From an estimated population once numbering millions of birds, introduced mammals, changes in land use and climate change have decreased the Hutton’s shearwater population significantly. A range of human related threats are driving population declines, impacting the last two remaining natural breeding colonies. 

Land-based threats include predation by introduced mammalian predators, unstable hillsides at breeding colonies post-earthquake, and light disorientation resulting in crash landings. Sea-based threats include fisheries, plastic pollution, and global warming induced marine heatwaves which are increasing sea surface temperatures (suppressing prey to cooler depths, decreasing foraging success, resulting in poor body condition and starvation).

Light Disorientation

Kaikōura lies in the flight path of these rare seabirds, which travel between the mountain breeding colonies and the sea from August to April. Route selection is based on temporal and spatial determinants. Visual cues needed for navigation to the ocean at night depend upon the ambient light of the moon and stars. Artificial lights interfere with celestial navigational cues, causing disorientation and crash landings (termed ‘fallout’).

Crash landing is more frequent during poor weather, when overcast skies and rain interfere with stellar navigational cues. Without these cues, nocturnal shearwaters are significantly impacted by disorientation from township lights. During inclement weather the sky glow of Kaikōura affects shearwaters more severely, which is further compounded by wet roads resembling the sea surface, and reflecting lighting back into the night sky.

The primary reason for this is light pollution from street lighting, as well as commercial and residential lighting. Crash landing primarily occurs on roads due to street lights, at commercial sites with flood lights, as well as in residential backyards. Localities such as Beach Road, the Esplanade and Torquay Street are typically sites with high numbers of downed shearwaters.

Hutton’s shearwater adults crash land throughout the breeding season from August to March; while young Hutton's shearwaters fledge during March and April, upon departing breeding colony burrows for their maiden voyage to sea. During the fledgling period hundreds of shearwaters can ground due to light disorientation.