The red-billed gull (Chroicocephalus novaehollandiae scopulinus), also known as tarāpunga and as the mackerel gull, is a native seagull of New Zealand, found throughout the country and on outlying islands including the Chatham Islands and subantarctic islands. It was formerly considered a separate species but is now usually treated as a subspecies of the silver gull (Chroicocephalus novaehollandiae).

The Māori name of this species is or . Its vernacular name is sometimes also used for the dolphin gull, a somewhat similar-looking but unrelated species that is found in coastal southern Chile, Argentina and the Falkland Islands. As is the case with many gulls, the red-billed gull was traditionally placed in the genus Larus.

A national survey of breeding red-billed gulls carried out in 2014–2016 recorded 27,831 pairs nesting in New Zealand. The authors of a study published in 2018 and based on the survey said that the accuracy of previous estimates was questionable, but that the species nevertheless appeared to have declined nationally since the mid-1960s. The study also discussed the possible reasons for the decline and made a proposal for future monitoring. Under the New Zealand Threat Classification System, the status of the red-billed gull changed from 'not threatened' in 2002 to 'nationally vulnerable' in 2016. The red-billed gull is a protected species under the Wildlife Act 1953. Penalties for disturbing or harming the birds include a fine of $100,000 and/or two years' imprisonment.

Description

The red-billed gull is the smallest gull commonly seen in New Zealand. It is about 37cm long, but is now considered to be a subspecies of the similar-looking silver gull found in Australia.

Population and distribution

Red-billed gulls breed in about 80 colonies on New Zealand's North and South Islands (mostly on the east coast of both islands), on offshore islands and in the Chatham Islands. Many birds fly several hundred kilometres between their breeding colony, which they return to each year, and sites where they spend the winter. Most birds stay within 400km of their breeding colony. There are also several inland breeding colonies at Sulphur Point at Lake Rotorua, which increased in size between the 1990s and 2010. Māori history recalls that in 1823, Te Arawa people living on Mokoia Island in Lake Rotorua were attacked by the Ngāpuhi tribe. The Te Arawa people were warned of the attack when a flock of red- and black-billed gulls disturbed by the attackers flew up, squawking an alert. After the battle, Te Arawa honoured the gulls by declaring them tapu or sacred.

The national population of red-billed gulls increased between the 1930s and 1970. A 1965 analysis estimated that at that time there was a national breeding population of 40,000 pairs of birds, At Mokohinau, an expedition in November 1933 observed thousands of nesting red-billed gulls.

The colonies at Three Kings Islands and Mokohinau have declined by more than 80 per cent since the 1990s, for reasons yet unknown: by 2016, there were only 1763 breeding pairs at the Three Kings Islands, and 58 at Mokohinau. The 2014–2016 study found that the largest mainland colonies were at Kaikōura (3210), Taiaroa Head (2145), Rotorua (2277) and Marsden Point (1190). The only large colonies on off-shore islands were at the Three Kings Islands (1763 pairs) and Stephens Island (1250 pairs). The increase in red-billed gulls at Taiaroa Head is due to predator control at the albatross colony there. It may travel 20km or more each day between roosting sites and feeding areas at sea. The red-billed gull is known for enjoying hot chips, although this is not a natural food. In bad weather the red-billed gull will move inland to feed on worms in wet fields.

<gallery mode="packed" heights="140" caption="Red-billed gull">

File:Red-billed gull portrait, New Brighton, New Zealand 03.jpg|Upper body

File:Chroicocephalus scopulinus LC0381.jpg|Adult with chick

File:Red-billed Gull in flight.jpg|Red-billed gull in flight

File:A balletic Looking Red Billed Gull.jpg|Landing

File:Red billed gull-07.jpg|Crouching

File:NeuseelandSeagulls.jpg|Second-winter, first-winter, and adult birds (first three, from front)

File:Red-billed gull (J).jpg|Juvenile bathing, Picton, New Zealand

File:Red-Billed Gull-Nueva Zelanda2.jpg|Eggs

File:Red billed gull-12.jpg|Comparison of adult (left) and immature (right) red-billed gulls in flight

File:Red-billed gull colony, Kaikōura, New Zealand 08.jpg|Sea gull colony in Kaikōura

File:Red billed gull 2.jpg|2021 photo

</gallery>

Notes

References

  • Mills, J. A. (1994). Extra-pair copulations in the Red-Billed Gull: Females with high-quality, attentive males resist. Behaviour, 128, 41–64.
  • Pons J.M., Hassanin, A., and Crochet P.A.(2005). Phylogenetic relationships within the Laridae (Charadriiformes: Aves) inferred from mitochondrial markers. Molecular Phylogenetics and Evolution 37(3):686-699
  • Tasker, C. R., & Mills, J. A. (1981). A functional analysis of courtship feeding in the Red-billed Gull, Larus Novaehollandiae scopulinus. Behaviour, 77, 222ff
  • Red-billed Gull, New Zealand Birds Online