Introduction

New Zealand's only endemic gull is the most threatened gull species in the world, and it's rapidly declining.

Highlights

New Zealand status: Endemic
Conservation status
: Nationally Critical
Found in: Mainly braided rivers South Island; scattered North Island coast and Rotorua
Threats: Predation, habitat disturbance

The black-billed gull has the unfortunate status of being the most threatened gull species in the world. Stronghold populations of this endemic species have rapidly declined by as much as 80%, resulting in its threat status being upgraded from Nationally Endangered to Nationally Critical in 2013.

Identifying black-billed gulls

Black-billed gulls are less likely to be found in towns and cities than other gulls, and are not commonly seen scavenging for food.

They have long, thin black beaks that are easily distinguished from the shorter and stouter bright red beak of the red-billed gull (although juvenile red-billed gulls have dark beaks that turn red as they age).

They are a similar size to red-billed gulls, but have pale wings and a thin black border on the wingtips rather than grey wings with more extensive black wingtips.

Adults weigh around 250–300 g and are about 37 cm long.

Nesting and breeding

Breeding sites are mainly the large braided riverbeds of the South Island, with scattered colonies on the North Island coast and at Lake Rotorua. In winter black-billed gulls are more coastal, so are often seen in estuaries, coastlines, harbours, and coastal parks.

Cup-shaped nests are woven from sticks and vegetation. The nests are on bare ground so are sitting targets for predators such as rats, hedgehogs and stoats.

Black-billed gulls are usually 2–3 years old before they breed for the first time. Between August and January the females lay 1 to 4 eggs. Both parents incubate the eggs, which hatch after about 20–24 days (if they aren’t eaten by predators). The chicks fledge after a further 26 days.

Threats

The main threat is predation by pests such as rats, stoats and hedgehogs

Human activity around nesting sites can disturb gulls, and even cause parents to abandon their nest. In 2013, a man was jailed for driving a vehicle through colonies, destroying nests and killing chicks and even adult birds.

Weed encroachment on river and lake beds has reduced suitable breeding habitat, forcing gulls to nest closer to the water’s edge where they are more likely to be flooded.

Disturbing protected birds and destroying nests is an offence under the Wildlife Act 1953 and can result in imprisonment and/or a fine of up to $100,000.

You can help

  • Trap pests near breeding colonies
  • Never feed gulls any food or scraps – some of our food is harmful to them

For details of community groups supporting black billed populations and information on pest trapping techniques contact DOC Rotorua or the Bay of Plenty Regional Council info@boprc.govt.nz.

Rotorua Office
Phone:   +64 7 349 7400
Address:   99 Sala Street
Rotorua 3010
Email:   rotorua@doc.govt.nz
Full office details
 

Help protect New Zealand's native birds

  • Volunteer with DOC or other groups to control predators and restore bird habitats.
  • Don’t throw rubbish into water ways or storm drains.
  • Set traps for stoats or rats on your property. Get more information from your local DOC office.
  • Put a bell on your cat's collar, feed it well, and keep it indoors at night.
  • Plant a range of native plants that provide food year-round to encourage birds into your garden.
When visiting parks and beaches
  • Only take dogs to areas that allow them, and keep your dog under control.
  • Prevent the spread of pests. Check your gear for mice and rats when visiting pest-free islands.
  • Use available access ways to get to the beach. Stay out of fenced-off areas. Leave nesting shore birds alone.
  • Get your dog trained in avian awareness, and help save forest birds like kiwi and weka.
  • Follow the water care code. Keep water craft speed to 5 knots within 200 metres of the shore.
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