Larus bulleri

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	CHARADRIIFORMES	LARIDAE

Scientific Name:

Larus bulleri

Species Authority:

Hutton, 1871

Common Name/s:

English	–	Black-billed Gull
Spanish	–	Gaviota Maorí

Assessment Information [top]

Red List Category & Criteria:

Endangered A2ce+3ce+4cd ver 3.1

Year Published:

2008

Assessor/s:

BirdLife International

Reviewer/s:

Butchart, S. & Mahood, S.

Contributor/s:

Hitchmough, R., McClellan, R. & Taylor, G.

Justification:
Surveys indicate that this species may have undergone a very rapid decline over three generations (32 years). It is therefore listed as Endangered.

History:

2006	–	Endangered
2005	–	Endangered
2004	–	Vulnerable
2000	–	Vulnerable

Geographic Range [top]

Range Description:	Larus bulleri is endemic to New Zealand. The majority of the population (78%) breeds in Southland⁵, mostly on the Mataura, Oreti, Aparima and Waiau rivers⁴. On the Oreti and Aparima, the number of breeding birds appears to have plummeted by as much as 90% in the last one to two decades^4,5,8. Upper Waitaki catchment populations declined between the 1960s and 1990s, with breeding colonies disappearing from six rivers³. Recent surveys at one minor colony in the Hunter Valley, Otago, showed numbers had dropped from 581 in 1969 to just 12, with the same trend seen in the nearby Makarora catchment area⁷. Overall, Southland counts estimated a minimum of 57,000 pairs in 1985-1986⁵, declining c.40% to 33,500 pairs in 1996-1997⁴. However, numbers and range continue to increase in the North Island, but these colonies are small and do not offset the South Island declines⁷. The most complete nationwide census was carried out in 1996-1997⁶, and counted 48,000 nests⁴. Some birds remain at colonies throughout the year, others move from inland breeding sites to the coasts².
Countries:	Native: New Zealand
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Powlesland (1998).
Population Trend:	Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	In the South Island, it breeds mainly on braided river systems^2,5. In the North Island, it uses sand-spits, shellbanks, lake margins and riverflats⁵. It often roosts and feeds on farmland, and scavenges in urban areas where refuse is available². It has a varied diet of terrestrial, freshwater and marine invertebrates, fish and shellfish^1,2. Breeding can begin after two years¹, but many individuals do not start until six years old, and adults may live over 30 years⁷.
Systems:	Terrestrial; Freshwater; Marine

Habitat and Ecology:

In the South Island, it breeds mainly on braided river systems^2,5. In the North Island, it uses sand-spits, shellbanks, lake margins and riverflats⁵. It often roosts and feeds on farmland, and scavenges in urban areas where refuse is available². It has a varied diet of terrestrial, freshwater and marine invertebrates, fish and shellfish^1,2. Breeding can begin after two years¹, but many individuals do not start until six years old, and adults may live over 30 years⁷.

Systems:

Terrestrial; Freshwater; Marine

Threats [top]

Major Threat(s):	Brown rat Rattus norvegicus takes eggs and chicks in the North Island. Remote video camaras have shown that Mustelids Mustela spp., and feral cats are major predators on South Island colonies, often taking hundreds of chicks in a season⁹. Hedgehogs may also take eggs. Recreational use of riverbeds and coastal areas is increasing, causing greater disturbance of nesting colonies⁵. River modification (including hydroelectric development, and water and gravel extraction) also has a significant impact. The spread of weeds is a major threat, reducing suitable nesting habitat on riverbeds^3,5.

Major Threat(s):

Brown rat Rattus norvegicus takes eggs and chicks in the North Island. Remote video camaras have shown that Mustelids Mustela spp., and feral cats are major predators on South Island colonies, often taking hundreds of chicks in a season⁹. Hedgehogs may also take eggs. Recreational use of riverbeds and coastal areas is increasing, causing greater disturbance of nesting colonies⁵. River modification (including hydroelectric development, and water and gravel extraction) also has a significant impact. The spread of weeds is a major threat, reducing suitable nesting habitat on riverbeds^3,5.

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway Studies of breeding biology, movements and dispersal are being undertaken. Localised and nationwide counts are ongoing. Habitat restoration and protection in the MacKenzie Basin is undertaken as part of Project River Recovery, including predator research and a public awareness campaign⁵. Conservation Actions Proposed Monitor key breeding populations. Initiate nest protection and trapping of introduced predators at key colonies. Initiate riverbed weed control if nesting habitat continues to be lost. Assess possible impact of further hydro-dam, gravel and water extraction proposals⁵.

Conservation Actions:

Conservation Actions Underway
Studies of breeding biology, movements and dispersal are being undertaken. Localised and nationwide counts are ongoing. Habitat restoration and protection in the MacKenzie Basin is undertaken as part of Project River Recovery, including predator research and a public awareness campaign⁵.

Conservation Actions Proposed
Monitor key breeding populations. Initiate nest protection and trapping of introduced predators at key colonies. Initiate riverbed weed control if nesting habitat continues to be lost. Assess possible impact of further hydro-dam, gravel and water extraction proposals⁵.

Citation:	BirdLife International 2008. Larus bulleri. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 21 May 2012.
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