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Fiordland Penguin Eudyptes pachyrhynchus



Justification

Justification of Red List Category
This species has a small breeding range and was previously believed to have a small population undergoing a continuing, and rapid, decline. However, recent population surveys across parts of the breeding range found substantially more penguins than previously thought, raising questions about the validity of previous estimates. The species is still suspected to be declining, but the population is considerably larger than the thresholds for listing as Vulnerable. There is no current evidence for rapid declines, but the high level of uncertainty in the rate of population reduction means that the species is now listed as Near Threatened. Further monitoring aimed at deriving population trends is required.

Population justification

Previously, the population has been estimated at c.5,500-7,000 mature individuals (Mattern 2013, Long 2017). More recently, population counts across parts of the species’s breeding range (Southwestland, Milford Sound, Stewart Island) suggest a considerably higher population number (Mattern and Wilson 2019). Due to the cryptic breeding habit and resulting difficulty of surveying the species, previous surveys have almost certainly underestimated the true population size considerably (Mattern 2013). Extrapolating from recent data, Mattern and Wilson (2019) suggest that the Fiordland penguin population more likely ranges between 12,500-50,000 mature individuals.

Trend justification
At some sites numbers appear to have declined, while increasing numbers have been reported from others, making it difficult to identify clear species-wide population trends (Mattern 2013). Previous estimates of Fiordland penguin numbers were based on a series of surveys conducted in the early 1990s which mainly involved observers with little to no experience in searching for cryptic breeding seabirds (McLean and Russ 1991). At Open Bay Island, there was an apparent decline of 33% between 1988 and 1995 (Ellis et al. 1998) but the question has been raised whether this apparent decline might have been a result of intensive research activities at that site (Mattern 2013). Patchy monitoring data obtained in the 1990s and early 2000s by the New Zealand Department of Conservation was recently used to model population trajectories; an annual population decline between 1.2 and 2.6% has been suggested (Otley et al. 2018), which would equate to a reduction of 34-60% over three generations.  However, the study by Otley et al., (2018) was based on nest-chick data, and due to the cryptic breeding behaviour of Fiordland Penguin, this traditional method of surveying populations is not thought to yield reliable data for this species (Mattern & Wilson, 2019). Additionally, these rates of decline stand in contrast to results of population surveys in South Westland and Milford Sound that found regional penguin population sizes to be much greater than those estimated since the areas were last surveyed in the early 1990s (Mattern and Wilson 2019). At Harrison Cove in Milford Sound, breeding pair numbers have remained stable since annual monitoring commenced in 2014 (Mattern and Ellenberg 2018). On Stewart Island, an August 2019 survey of parts of the coast tentatively estimated “between 300 and 800 breeding pairs” on Stewart Island (Robin Long, unpublished report) where previous surveys had recorded “a total of 32 penguins” (Studholme et al. 1994). Deriving a population trend is difficult, but overall, this species is suspected to be experiencing declines. Although Otley et al., (2018) suggest a high rate of decline, other studies have shown population increases. Therefore, the overall suspected rate of decline is tentatively placed here in the range of 20-29% over three generations (c.35 years).

Distribution and population

Eudyptes pachyrhynchus nests on the west to south-west coast of the South Island, New Zealand, from Bruce Bay in South Westland, to Coal Island in southern Fiordland. They are also found breeding on Solander Island, Codfish Island/Whenua Hou, along with Stewart Island and several of its offshore islands (Mattern and Wilson 2019). Non-breeding dispersal ranges from the subtropical front to the polar front with most birds foraging along the sub-antarctic front, travelling up to 3,000 km away to the Southwest of New Zealand. During the non-breeding season, birds have been observed on the Snares, Auckland, Campbell and Macquarie Islands. They are also common visitors to Tasmania, and are occasionally reported from mainland Australia (Mattern and Wilson 2019). 

Ecology

This species breeds in loose colonies along stretches of coastline in habitats ranging from mature temperate rainforest and dense scrub, to coastal caves and rocky shorelines. Penguins arrive at their breeding sites from mid-June onwards, with most nests established by mid-July. Two eggs are laid, which are incubated by both parents and hatch after 33 days (Warham 1974). Chicks fledge around mid- to late November. A diet study on the West Coast found that penguins brought predominantly squid (85%) ashore, followed by krill (13%) and fish (2%) (van Heezik 1989). Penguins from Codfish Island/Whenua Hou took primarily fish (85%) and squid (15%) (van Heezik 1990). Breeding penguins show site-dependent differences in foraging ranges, with birds from the Jackson Head, West Coast, and Open Bay foraging within 20-100 km radii from their breeding colonies, while penguins breeding in Milford Sound remained within the fiord most of the time (foraging radius <10 km) (Mattern and Ellenberg 2016; Poupart et al., 2019). On Codfish Island/Whenua Hou, Fiordland penguins were found to forage either very close inshore (<500 m of the island’s coast, presumably foraging in kelp forest) or travelled to deeper waters about 20-40 km west of the island (Mattern and Ellenberg 2018). Outside the breeding season, Fiordland penguins forage deep into the sub-antarctic south of Australia (Mattern et al. 2018, Mattern et al. unpublished data).

Threats

Introduced terrestrial predators are an imminent threat. Stoats Mustela erminea are considered the most significant predator of the species at present (Ellenberg 2013, Wilson and Long 2017), with three trapped in 2016 following observations of stoats preying upon chicks at Jackson's Bay colony (Mattern and Ellenberg 2016). In this and the preceding year productivity at this site was very low, but improved in 2017 (Mattern and Ellenberg 2016). Dogs also represent a potentially significant predator, particularly when moulting adults are confined ashore for 20-30 days, during which time a single dog would have the potential to wipe out a whole colony (DOC 2012). Feral cats Felis catus, rats Rattus spp., Weka Gallirallus australis (Marchant and Higgins 1990, Mattern 2013) and Common Brushtail Possum Trichosurus vulpecula are also potential predators, but they appear to have negligible impacts on Fiordland Penguin populations (Mattern and Ellenberg 2016). 

Resource competition with squid fisheries (Ellis et al. 1998) and bycatch are both threats imposed by local fisheries. In 2011 annual bycatch mortality was estimated to be between 38-176 birds (Ellenberg 2013) with set nets of particular concern close to shore or within the fiords themselves (e.g. Milford Sound). Birds are occasionally disturbed by humans at nest-sites (Ellenberg et al. 2015), with human disturbance in the more accessible colonies in South Westland anecdotally attributed as causing nest failures and a decline in population (Wilson and Long 2017; DOC 2012). Small numbers are killed on roads (DOC 2012). The pathogen Leucocytozoon tawaki has been identified from the species, but infections are of low prevalence and there appear to be no ill-effects reported (Jones and Shellam 1999). Pollution could become a major threat if proposed deep-sea oil exploration off the West Coast proceeds (Mattern 2013), and oil spills represent an ongoing, chronic threat with potential for a dramatic incident, most likely limited to a portion of the breeding range. El Niño events were found to have a detrimental effect on the breeding success of Fiordland penguins from the West Coast, although penguins breeding in Fiordland seem to be less affected by the climate phenomenon (Mattern and Ellenberg 2016).

Conservation actions

Conservation Actions Underway

The New Zealand Department of Conservation (DOC) established a Fiordland penguin Recovery Strategy 2012-17 plan that included continued population monitoring at representative sites, implementation of island biosecurity measures, and the investigation of the effects of predator control (DOC 2012). As part of a five-year project commenced in 2014, the marine ecology (foraging ranges, diving behaviour, diet composition) of breeding Fiordland penguins was studied across their entire breeding range; the project also investigated the pre-moult dispersal of adult penguins (Mattern and Ellenberg 2016; Mattern and Ellenberg 2020). The species’s non-breeding migration will be investigated between 2016 and 2021 (S. Waugh, pers. comm.). A video monitoring study examines the impact of introduced terrestrial predators on breeding Fiordland penguins (Wilson and Long 2015). Population surveys are being carried out at additional sites throughout South Westland and Stewart Island which have not been surveyed recently, or at all (R. Long 2018/19, unpublished data). The Department of Conservation has previously regularly monitored nest numbers at sites throughout the species's breeding range (Ellenberg et al. 2015); this programme was discontinued in 2016. At Harrison Cove in Milford Sound, an automatic wildlife monitoring system is being trialled for long-term population monitoring (Mattern 2019). The breeding islands are fully protected (S. Garnett in litt. 2020).

Conservation Actions Proposed

Expand the use of standardized census methods (Ellenberg et al. 2015) and survey areas of coastline not surveyed in the 1990s (Ellis et al. 1998). Predator eradication/control – particularly mustelids – is necessary to prevent reproductive failure and mortality (Mattern 2013). Establish guidelines to control visitor access to colonies. Obtain legal protection for accessible colony sites (Taylor 2000).  Investigate the viability of automated monitoring solutions to be deployed at representative locations within the species’ breeding range (Mattern and Wilson 2019).

Identification

60 cm. Medium-sized, yellow-crested, black-and-white penguin. Dark, bluish-grey upperparts. Darker head. Broad yellow eyebrow-stripe that drops down neck. Most have 3-6 whitish stripes on cheeks. Similar spp. Only crested penguin with white stripes. Snares Island Penguin E. robustus has pink skin at base of bill. Erect-crested Penguin E. sclateri has erect crest. Rockhopper penguins E. chrysocome and E. moseleyi have crests that begins with a thin eyebrow-stripe.

Acknowledgements

Text account compilers
Trathan, P. N., Clark, J.

Contributors
Ellenberg, U., Garcia Borboroglu , P., Garnett, S., Long, R., Mattern, T., McClellan, R., Otley, H., Poupart, T., Seddon, P., Taylor, G.A., Webster, T., Wilson, K.-J., van Heezik, Y. & Pearmain, L.


Recommended citation
BirdLife International (2021) Species factsheet: Eudyptes pachyrhynchus. Downloaded from http://www.birdlife.org on 25/02/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/02/2021.