Sky Tower and Harbour Bridge Dim Their Lights to Guide Young Seabirds to Safety

Every year in autumn, thousands of young Cook’s petrels leave their nest burrows on island sanctuaries north of Auckland and launch themselves into the night sky for the first time. They are heading for the open Tasman Sea and beyond, following instincts laid down over millions of years. What they are not built for is a city blazing with artificial light — and for some of them, Auckland’s skyline has been a death sentence.

Cook’s petrels, known as tītī in te reo Māori, breed on Hauturu (Little Barrier Island) and Aotea (Great Barrier Island), two of the largest seabird sanctuaries in the country. Each autumn the season’s fledglings depart, flying at night and navigating by the stars. Urban light pollution scrambles that navigation. Drawn toward the glow of the city, juveniles can end up grounded on streets and rooftops — and once on the ground, they cannot take off again. Unlike many birds, petrels need a cliff edge or raised surface to launch from. A flat footpath is a trap.

BirdCare, the Auckland wildlife rehabilitation service, has been picking up these birds for years and recording the toll. Last April and May the organisation admitted approximately 100 fledgling Cook’s petrels. Only around 60 percent were successfully rehabilitated and released. The rest did not survive.

This year the numbers look different. In the past two weeks, BirdCare has admitted just 26 grounded birds — noticeably fewer than the equivalent period last year. The organisation is cautiously crediting a change in approach from two of Auckland’s most visible landmarks.

SkyCity has committed to dimming the Sky Tower and minimising the blue and violet wavelengths in its public display lighting from February through June, covering the full fledgling season. The company’s switch to LED lighting in 2019 had unwittingly made the problem worse — the new fittings were significantly brighter than what they replaced, effectively doubling the tower’s luminosity at exactly the time of year when bird disorientation was already a concern.

Vector, which operates the Harbour Bridge lights, has gone further. It has extended its lighting reduction from three months to six, running the bridge at 50 percent intensity from 31 January through to 31 June. Together, the two changes represent a meaningful reduction in the brightness of the most prominent features in the city’s night skyline.

Rashi Parker, BirdCare’s fundraising and advocacy manager, said the connection with SkyCity came about through media coverage last year. “Last year, thanks to RNZ, we were actually able to connect with SkyCity,” she told RNZ. The conversations that followed led directly to the commitments now in place. “Both groups were really responsive and committed to reducing their public display lighting by 50 percent during the key migratory seasons,” she said.

Parker has not stopped there. She is now calling on large apartment complexes in the city to follow suit, dimming their lights and shifting to warmer colour spectrums during the fledgling season. The physics of why this matters is straightforward — shorter wavelengths at the blue and violet end of the spectrum are more disorienting to birds than the warmer amber and red tones. The ask is not darkness, but a slightly different kind of light.

Karen Kermadec of the Seabird Trust and DOC Wildlife Response Squad described the difficulty of the recovery work when birds are found too late or already harmed. “It is often heartbreaking for the volunteers because some of the birds are already injured,” she said.

Cook’s petrels are not the only species at risk. Chris Gaskin of the Seabird Trust has flagged that other birds are being pulled in by the same problem, noting that “little storm petrels are also being drawn into the lights.” For a country where seabirds are already under pressure from mammalian predators, fishing bycatch, and habitat loss at sea, urban light pollution represents yet another hazard concentrated in a narrow seasonal window.

New Zealand is home to more seabird species than anywhere else on Earth. Many of those species breed on islands just offshore from major cities — a situation almost unique to this country and one that creates an ongoing collision between the ecological and the urban. The Cook’s petrel breeds within a couple of hours’ flight of central Auckland. That proximity, which makes the islands so valuable as sanctuaries, also means fledglings pass directly through the city’s lit-up airspace every autumn.

The steps taken by SkyCity and Vector this season demonstrate that these collisions are not inevitable, and that relatively modest adjustments can produce measurable results. Corporate willingness to make changes when presented with the evidence is not something that can be taken for granted, which makes the partnerships BirdCare has built over the past year genuinely significant. The challenge now is to broaden that willingness beyond two high-profile landmarks and into the wider fabric of the city.

Anyone who finds a grounded seabird can call the DOC hotline on 0800 DOC HOT (0800 362 468) for advice on what to do next. The birds are fragile when grounded but can survive with prompt care and the right release conditions.

Have you ever found a grounded seabird in Auckland or another NZ city? Share your experience in the comments below.