VU
Bounty Shag Leucocarbo ranfurlyi



Justification

Justification of Red List Category
This species is classified as Vulnerable because it has a very small population and breeding range, rendering it susceptible to stochastic events and human impacts. If population fluctuations are shown to be extreme, or if there is any population decline, it may warrant uplisting to a higher threat category.

Population justification
In February 2013, the first bird count including an entire circumnavigation of the Bounty Islands group was carried out. The mean count of Bounty Island shags on land was 1,386.5 ± 75.5 birds (SD, range 1311-1462; roughly equivalent to 874-975 mature individuals) and 150 birds were also seen swimming or flying in the area.

Trend justification
Boat-based surveys conducted in 2011 suggest that numbers were similar to those counted in 2005 (J. Hiscock in litt. 2012), probably indicating that the population is stable overall.

Distribution and population

Phalacrocorax ranfurlyi is restricted to the Bounty Islands, New Zealand. In 1978, 569 pairs were observed on 11 islands (Robertson and van Tets 1982). In 1997, a repeat census was attempted, but proved very difficult because it was not possible to land on the islands. However, colonies were noted on 13 islands, and 120 nests and 368 birds were counted (A. M. Booth in litt 1998). The islands were surveyed again from land in 2005, when 618 individuals were counted (R. Hitchmough in litt. 2005). In 2011, 393 nests were reported (Amey 2012). However, all of these counts covered only parts of the Island group. Although it is not known whether differences in the estimates are due to differing survey methods, differences in peak breeding times between years or a true change in numbers, a comparison with other species surveyed at the same time suggests that they show genuine trends (Taylor 2000, R. Hitchmough in litt. 2005). Surveys in 2011 suggest that the overall population has remained stable since 2005 (J. Hiscock in litt. 2012). In February 2013, the first bird count including an entire circumnavigation of the Bounty Islands group was carried out. The mean count of Bounty Island shags on land was 1,386.5 ± 75.5 birds (SD, range 1311-1462) and 150 birds were also seen swimming or flying in the area. Previous counts of individual birds (not nest counts) were undertaken in November and recorded 366 birds in 1997, 428 birds in 1998, 633 birds in 2004 and 304 birds in 2008 (Robertson and van Tets 1982; De Roy and Amey 2004; Clark et al. 1998; Russ and Terauds 2008). The population is likely to fluctuate markedly as a result of the effects of weather conditions on feeding (A. J. D. Tennyson in litt. 1994). The species's foraging range is assumed to be up to 24 km offshore (cf. New Zealand King Shag P. carunculatus).

Ecology

It breeds mostly on narrow cliff-side ledges, with nests often as little as 1 m apart (Robertson and van Tets 1982, Heather and Robertson 1997). It feeds on fish, snails, squid, isopods and crabs (Robertson and van Tets 1982).

Threats

Sea level rise and other weather anomalies associated with climate change is a factor potentially threatening the whole population. Estimates specific to New Zealand calculated a rate of sea-level rise of 2.8 ± 0.5 mm yr-1 during the 20th century (supported by time-gauge records of 2.1 ± 0.1 mm yr-1 between 1924 and 2001) which is significantly faster than the rates reconstructed for the preceding four centuries (Gehrels et al. 2008), with 31% of the species was classified with medium-high risk of exposure to coastal flooding (Spatz et al. 2017). With a greatly restricted range, covering relatively low-lying islands, this species is particularly susceptible to climate change through sea-level rise and climatic shifts.

Nesting sites may be restricted by large numbers of fur seal Arctocephalus forsteri. A survey in January 1994 estimated the presence of at least 21,500 fur seals, occupying over 50% of the available land area (Taylor 1996, Baird 2011).

So far, the Bounty Islands have been free of introduced mammals (Taylor 2000) but invasive species could pose a serious threat if introduced. Pest quarantine measures are needed to prevent new animal and plant pest species reaching the Bounty Islands.

Conservation actions

Conservation Actions Underway
The Bounty Islands are nature reserves and are free of introduced predators. In 1998, they were declared part of a World Heritage Site.

Conservation Actions Proposed
Complete a full census of all colonies every 10 years, including a census of nest-sites and breeding pairs (A. D. Roberts in litt. 1999, Taylor 2000). Turn the World Heritage Site territorial sea (out to 12 nautical miles) into a marine reserve and restrict all fishing (B. Weeber in litt. 2000).

Identification

71 cm. Large, black-and-white cormorant. Black head, hind neck, lower back, rump, uppertail-coverts, all with metallic blue sheen. White underparts. Pink feet. White patches on wings appear as bar when folded. Caruncles absent. Voice Male makes call during displays only.

Acknowledgements

Text account compilers
Taylor, J., Mahood, S., Fjagesund, T., Martin, R., Benstead, P., McClellan, R., Miller, E., Moreno, R., Pilgrim, J.

Contributors
Taylor, G.A., Roberts, A., Tennyson, A., Moore, P., Weeber, B., Booth, A., Hiscock, J., Kennedy, M.


Recommended citation
BirdLife International (2019) Species factsheet: Leucocarbo ranfurlyi. Downloaded from http://www.birdlife.org on 19/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/10/2019.