Justification of Red List Category
This species is classified as Endangered because its population is estimated to have declined very rapidly over the last three generations, and it is almost certainly still declining. Furthermore, it has a very small breeding range, which may now be restricted to just two locations.
The most recent population survey conducted in 2011 found 34,226 nests on the Antipodes (Hisock and Chilvers 2014); on the Bounty Islands there were an estimated 26,000 nests in the same year (Miskelly 2013), leading to an estimated 60,226 nests in total. This would equate to 120,452 nesting individuals, but it is assumed that only around 80% of mature individuals engage in breeding each year, so the number of mature individuals is estimated to number c.150,000.
Population trends indicate a severe decline between the mid-1970s and mid-1990s (Davis 2013). On the Bounty Islands, estimated numbers were 115,000 pairs (Robertson and van Tets 1982) in 1978, apparently declining to 28,000 pairs by 1997, representing a 75% decline (Taylor 2000). However, the 1978 numbers have recently been called into question (Wilson and Mattern 2019). Population surveys conducted in 1997 (Clarke et al. 1998), 2004 (de Roy and Amey 2004), 2014 (J. Amey, unpublished data), and 2019 (T. Mattern, unpublished data) indicate that parts of the Bounty Island population might actually have been relatively stable for the last two decades. However, as surveys covered only small portions of the Bounty Island archipelago, an ongoing population decline cannot be ruled out definitively.
On the Antipodes Islands an estimated 115,000 breeding pairs were recorded in 1978, which declined extremely rapidly to 52,000 pairs by 1995 (Taylor, 2000). The rate of decline appears to have subsequently slowed somewhat; between 1995 and 2011 the number of penguin nests declined by 23% (Hiscock and Chilvers 2014), although this is still equivalent to a 61% decline over three generations (36 years, based on methods in Bird et al. ) in this population.
Overall it appears that the population decline apparent until the 1990s has since slowed somewhat, which corresponds to the trend observed in the sympatrically breeding Southern Rockhopper Penguins (Morrison et al. 2015). However, even if populations on Bounty Island had only declined from 28,000 pairs in 1978 to 26,000 pairs in 2011, the very rapid decline in the Antipodes still results in a decline of 52% over the past three generations (36 years). More reliable survey data is required to confirm the reduction in the rate of decline.
Eudyptes sclateri breeds on the Antipodes and Bounty Islands (20 km2 and 1 km2 respectively), New Zealand. In the mid-20th century the species was recorded breeding on the New Zealand mainland, although these were individual pairs that were not part of a larger population (Richdale 1950). Outside the breeding period birds have been reported on other sub-Antarctic islands, such as Campbell Island (Miskelly et al. 2015) and the Snares Islands (Morrison and Sagar 2014), and it is a frequent visitor to the New Zealand mainland and the Chatham Islands (Miskelly 2013). Outside New Zealand territory, the species has been observed along the southern coasts of Australia, and the Kerguelen and the Falkland Islands (Miskelly 2013).
It nests in large, dense, conspicuous colonies, numbering thousands of pairs, on rocky terrain, often without substantial soil or vegetation, from the spray zone to 75 m elevation (Davis 2013, Hiscock and Chilvers 2014). Like all Eudyptids, Erect-crested Penguins are obligate brood reducers and rear only one chick. The egg-size dimorphism is the most extreme for any bird with B-eggs being 85% heavier in mass than A-eggs (Davis 2013). Diet composition has not been studied but it assumed to consist of krill, squid, and fish (Davis 2013).
With a severe lack of data on the species it is difficult to assess what causes population declines (Davis 2013). The absence of introduced terrestrial predators disrupting penguin populations on the mainland points towards sea-based threats, which most likely consist of changes in marine productivity due to ocean warming and, potentially, interactions with fisheries (Trathan et al. 2015).
Conservation Actions Underway
Both islands are Nature Reserves and part of a World Heritage Site designated in 1998. Opportunistic monitoring of population size takes place.
Conservation Actions Proposed
Survey a sample of Antipodes Island colonies every five years, and re-photograph photo-points from the 1978 and 1995 expeditions. Survey Proclamation Island (Bounty Islands) every five years (Hiscock and Chilvers 2014). Compare aerial and ground surveys of the Bounty Islands to ascertain the viability of using the former method for monitoring colonies (Taylor 2000). Conduct detailed studies to determine foraging ranges, commercial fisheries interactions, and oceanographic or climatic changes (Davis 2013). Bring in international agreements for the creation of further Marine Protected Areas and agreements on the regulation of fisheries, oil and other marine activities.
60 cm. Medium-sized, yellow-crested, black-and-white penguin. Bluish-black to jet black upperparts. White underparts. Broad, bright yellow eyebrow-stripe extends over eye to form short, erect crest. Similar spp. Differs from all other crested penguin species in having an erect crest.
Text account compilers
Trathan, P. N., Clark, J.
Amey, J., Booth, A.M., Ellenberg, U., Hiscock, J., Houston, D., Taylor, G.A., Webster, T., van Heezik, Y., Garcia Borboroglu , P., Mattern, T., McClellan, R., Seddon, P., Benstead, P., Calvert, R., Mahood, S., Moreno, R., Taylor, J. & Martin, R.
BirdLife International (2021) Species factsheet: Eudyptes sclateri. Downloaded from http://www.birdlife.org on 04/03/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 04/03/2021.