World Migratory Bird Day: dim lights for our manu at night

Department of Conservation —  08/10/2022

Today (Saturday 8th) we are celebrating World Migratory Bird Day.

(Déjà vu? Yes, we celebrated World Migratory Bird Day back in May. There are two each year, for the Southern and Northern migrations.)

Banded dotterels in flight.
📷: Leon Berard –

World Migratory Bird Day is an International Day of Awareness as birds around the world begin their seasonal migrations. This year the theme focuses on light pollution.

Each year, millions of birds die because of light pollution. It is a pervasive, global, and increasing problem for our taonga.

More than 80% of the world lives under light-polluted skies, and it’s estimated that one-third of the global population can’t see the stars at night. Natural light cycles, such as from the moon, have been eliminated.

Natural darkness is as important as clean water, air, and soil, and is a huge issue in conservation. It needs protection, here in Aotearoa and around the world. Yet, artificial light is steadily increasing by at least 2% per year globally, and many animals die every year because of light pollution.

Light pollution obscured the night sky and wreaks havoc on wildlife.
📷: Stephen Rahn

Six simple steps to combat light pollution

In Aotearoa, we are a member of the Convention on Migratory Species, where we work with other countries to conserve our migratory species such as Antipodean albatross.

There are six simple best practice guidelines that everyone can apply to help address light pollution and save wildlife:

  1. Start with natural darkness and only add light for specific purposes.
  2. Use adaptive light controls to manage light timing, intensity, and colour.
  3. Light only the object or area intended – keep lights close to the ground, directed, and shielded to avoid light spill.
  4. Use the lowest intensity lighting appropriate for the task.
  5. Use non-reflective, dark-coloured surfaces.
  6. Use lights with reduced or filtered blue and violet wavelengths.

You can do your part by applying these guidelines yourself! Help dim lights for manu at night!

This is a video from Australia, but the guidelines remain the same: wildlife is threatened by light pollution no matter where we are.
📷: Australian Government

How light pollution affects our taonga, and what we can do about it

Just like moths drawn to a lamp, lights can attract, repel, or disorient birds. Tragically, birds can collide with buildings, vessels, and other man-made structures.

Not all the impacts of light pollution are quite so obvious, though. Lesser-known impacts include changing animal’s internal clocks and disrupting their hormone cycles, including melatonin, the sleep hormone. Light pollution also affects us like this!

It can affect communication, feeding, and migratory behaviour. Light pollution can also disconnect populations by creating barriers that individuals won’t move through, similar to how roads can be barriers to animal migration. The effect of such barriers is that habitats are even further fragmented, with resulting population declines.

Impacts of light pollution on seabirds

Aotearoa is the seabird capital of the world, but our seabirds are not safe from light pollution. Every year, naive fledglings and adult birds crash-land on roads and in towns after being attracted and disorientated by lights. Some examples are tītī/Cook’s petrels in Tāmaki Makaurau/Auckland, taiko/Westland petrels in Punakaiki, and tītī/Hutton’s shearwaters in Kaikoura.

Seabirds also collide with vessels out at sea when these are brightly lit. For example, marine light pollution affects kuaka/Whenua Hou diving petrels around Whenua Hou/Codfish Island. Once crash-landed, seabirds cannot take off to sea by themselves, because they need winds or elevated platforms (e.g., trees or cliffs) to take to the air again. Once grounded seabirds are at risk from invasive predators and cars on land or water-logging and hypothermia on vessels.

Taiko/Westland petrel prior to release after having crash-landed due to light pollution.
📷: Kate Simister

Recently we attached light-sensitive tracking tags to 179 seabirds, to study when they encounter light pollution while out at sea. The good news is that our rarest seabirds, Chatham Island tāiko, kuaka/Whenua Hou diving petrel, and Chatham petrel, seem to encounter little light pollution out at sea. However over one third of the tracked shearwaters and prions encountered light pollution across the Pacific. You can explore the research on an interactive map here:

Shorebirds are also vulnerable to light pollution

Some shorebirds migrate between breeding and non-breeding grounds twice annually in line with the seasons. For all these species, migration may be the most challenging stage of the year for survival, as conditions encountered en route are often unfamiliar and unpredictable.

Aotearoa is part of the East Asian Australasian Flyway, a bird migration path that stretches from Russia to New Zealand, encompasses 22 countries, and is used by over 50 million birds:

📷: Adrian Riegen, Miranda Shorebird Centre

We are part of a network which cooperates across this flyway and has already protected 150 wetland sites which are critical for migration. Four of these are in Aotearoa: in the Firth of Thames, Farewell Spit, Ihutai/Avon-Heathcote Estuary, and Awarua Bay.

Many of our migratory birds will stopover in Asia on their flights. The edge of East Asia is one of the most densely populated places on the globe. Approximately one third of all humans living along the seaboards of East and Southeast Asia. With increasing construction and increasing light pollution, we see a corresponding decline in bird populations.

Skyscrapers in Shenzhen City with the wetlands of Mai Po in the fore ground, which are crucially important for shorebirds.
📷:(Permission granted by Earth.Org First published by Earth.Org on Nov 22 2019.).

Artificial lights and skyglow can disorient migratory shorebirds and affect their flight trajectories, with fatal consequences. Additionally, light pollution may also affect the invertebrates that shorebirds rely on, leading to declines in food supplies, creating challenges at their refuelling stopovers.

These migratory species which touch down in New Zealand – including kuaka/bar-tailed godwits and huahou/red knots – are threatened by habitat degradation, predators, and – you guessed it – light pollution.

Huahou or red knot foraging for shellfish in Awarua Bay Southland NZ.
📷: courtesy of Craig McKenzie via

The kuaka/bar-tailed godwit, which visits us in the summer, undertakes a heroic migration to Alaska and back each year.  This journey is over 10,000km and they may fly nonstop for a week or more and arrive having lost over half their body weight. Any extra factor, such as a lack of food, may be a death sentence.

Thus, the epic migrations of shorebirds have become even more challenging due to light pollution across the globe.

…and some honorary “birds”

The 2021 winner of “manu of the year”, the long-tailed bat/pekapeka, is also affected by light pollution. We’re collaborating with the University of Waikato to help further research this. Watch this space! So far, we know that our other pekapeka, the lesser short-tailed bat will call less in lit areas and avoids flying and landing when light is present. Keeping dark places dark is very important for our bat taonga as well.

The future is bright (by that we mean dark)

DOC is working hard to implement these guidelines for the sake of our taonga. New, additional guidelines, focusing on migratory land birds and bats, are also being developed under the Convention on Migratory Species, and DOC is providing input.

We work with various partners, including iwi, local and national government departments, environmental NGOs, and industry, to reduce the impacts of light pollution, but more work needs to be done. That is where the six best practice guidelines come in.

How you can help

You can help by dimming the lights for our manu and by further spreading the word! Follow the six simple steps to combat light pollution. You can make these changes at your home, your workplace, your school, your vessel, or ask your local council what they are doing to make positive changes. 

Check out a dark sky reserve in your area, such as the Dark Sky Project in Tekapō, or see if there is a Dark Sky association working in your area. These reserves are valuable places for people to learn about the importance of reducing light pollution and offer some of the best stargazing in the world.

If you find a crash-landed seabird, call your local DOC office or 0800 DOC HOT to get crash-landed birds the help they need. There are also special services in some regions with high crash-landing rates:

  • Tāmaki Makaurau/Auckland: SPCA Mangere (09 256 7300) and BirdCare Aotearoa (027 816 9219)
  • Kaikoura: Hutton’s Shearwater Charitable Trust (021 049 1486)

One response to World Migratory Bird Day: dim lights for our manu at night


    This is a wonderful and informative post. Who wrote this?