Justification of Red List Category
This species is listed as Endangered as the small population is suspected to have undergone a very rapid decline over the past three generations (c.30 years) as a result of ongoing threats including disease, invasive predators and fisheries by-catch.
Past estimates suggested there were around 1,700 breeding pairs (3,400 breeders), with an estimated 60% of these in the sub-Antarctic (Auckland Campbell Islands) (Seddon et al. 2013), but recent declines on mainland New Zealand indicate the total population is lower that previously thought. Surveys in the Auckland Islands in 2017 estimated 577 pairs (Muller et al., 2020). The Campbell Island population was last estimated in 1992 at 350-540 pairs (Moore 2001). Stewart Island and outliers were estimated at 220-400 pairs in 1994, dropping to 178 pairs in 1999-2001 (Massaro and Blair 2003). In 2011-2012 South Island's south-east coast was thought to hold 452 pairs (Seddon et al. 2013), in 2015, there were 252 breeding pairs counted on the South Island, while in 2019, the total number of breeding pairs counted in the South Island was 227 (DOC; unpublished data). Based on these most recent estimates, the global population is estimated to be in the range of 2,684 - 3,064 mature individuals, rounded here to 2,600 - 3,000 mature individuals.
There is very little movement between the mainland and sub-Antarctic and genetic analyses reveal two distinct sub-populations (mainland New Zealand including Stewart Island, and the sub-Antarctic Auckland and Campbell Islands; Boessenkool et al. 2009).
The species is thought to be declining overall as a result of a number of threatening processes, principally introduced predators, habitat conversion, changes in the marine environment, and disturbance.
It has been suggested that the population on the South Island may show fluctuations, but population modelling of a well-studied colony on the Otago Peninsular showed rather that a dramatic decline has taken place: a 76% decline between 1996 and 2015 (Mattern et al., 2017). A consolidation of breeding numbers over the past 20 years in light of this decline reinforces the concern (New Zealand Department of Conservation [DOC] 2020, Te Rūnanga o Ngāi Tahu, Department of Conservation, Yellow-eyed Penguin Trust, and Fisheries New Zealand. 2020): in 1999 there were 741 breeding pairs in the northern population (including Stewart Island/Rakiura and surrounding islands), while the total recorded in 2019 is 265 pairs. This is equivalent to a 78.5% decline over three generations (29.7 years, after Bird et al. 2020). The decline appears to have accelerated after 2012: a 52% decline was recorded across the South Island between 2012 and 2019 (Seddon et al. 2013, DOC unpublished data, 2020). In 2011-2012 South Island's south-east coast was thought to hold 452 pairs (Seddon et al. 2013), in 2015, there were 252 breeding pairs counted on the South Island, while in 2018/2019, the total number of breeding pairs counted in the South Island was 227 (DOC; unpublished data). On Te Rere, Southland, the population has declined from 81 individuals in 2008, to 20 in 2018 and nests from 23 to 5 in the same time (Wood, 2018). The population size on Stewart Island and outliers were estimated at 220-400 pairs in 1994, dropping to 178 pairs in 1999-2001 (Massaro and Blair 2003).
Trajectories in the sub-Antarctic populations are not known but there is no evidence of declines on the Auckland islands between 1989 and 2017 (Moore 1992, Muller et al. 2020). The Campbell Island population has not been assessed since 1992. In light of the very rapid declines in the northern population and poor knowledge of the southern, overall declines are suspected to fall in the range 50-79% over the past three generations (29.7 years). These declines are likely to continue at this rate in the near future, however they are of such magnitude in the north that the contribution of this population to the overall population size will mean that the future rate of decline is suspected to be at a reduced rate.
Megadyptes antipodes is endemic to New Zealand where it breeds on the South Island's south-east coast (452 pairs in 2011-/12 [Seddon et al. 2013], 225 pairs 2018/19 [DOC unpublished data, 2020]), Stewart Island and outliers (178 pairs in 1999-2001 [Massaro and Blair 2003]), the Auckland Islands group (520-570 pairs in 1989 [Moore 1992] and 577 pairs in 2017 [Muller et al., 2020]) and Campbell Island (350-540 pairs in 1992 [Moore 2001, Seddon et al. 2013]). The South Island population is genetically distinct from the two sub-Antarctic populations (inferred immigration rate 0.003 per generation; Boessenkool et al. 2010). Adults are sedentary and generally forage within 50 km of their breeding colonies (Mattern et al. 2007), but juveniles may disperse north as far as the Cook Strait (Marchant and Higgins 1990).
In the South Island the species tends to nest in forest and scrub remnants, amongst pasture and in exotic vegetation (McKay et al. 1999, Ratz and Murphy 1999, Seddon et al. 2013). Nests generally have surrounding vegetation that conceals them from visual contact with conspecifics (Seddon and Davis 1989), but this is not believed to be a prerequisite for successful breeding (Clarke et al. 2015). Two eggs are laid from mid-September to mid-October, with hatching occurring at the beginning of November. Chicks fledge from mid-February to mid-March (Seddon et al. 2013). Prey species on the mainland are primarily opalfish, sprat, silversides, ahuru, blue cod and arrow squid; red cod used to be an important prey species in the 1980s (van Heezik 1990, Moore and Wakelin 1997, Browne et al. 2011). Blue Cod DNA has been found in 100% of all faecal samples taken from mainland Yellow-eyed Penguins, indicating a significant change in prey quality and type (M. Young et al. unpublished). Yellow-eyed Penguins forage predominantly along the seafloor (87% of all dives) whereas pelagic dives mostly occur when they travel back to their breeding areas (Mattern et al. 2007). They occasionally dive deeper than 120 m but predominantly forage in depths of less than 100 m (Seddon et al. 2013). Individuals have preferred foraging sites that they revisit on subsequent foraging trips and even between years (Moore 1999, Mattern et al. 2007). They appear very sensitive to disturbance and degradation of their benthic foraging habitat (Browne et al. 2011, Ellenberg and Mattern 2012, Mattern et al. 2013).
By-catch mortality in the commercial gillnet fisheries is thought have driven significant declines over the past two decades, both on predator-free islands, such as Whenua Hou, and along the mainland coast (Ellenberg and Mattern 2012, Mattern et al. 2017). Current estimates are 17 (95% CI 6-34) birds caught annually (Ministries for Private Industries, 2019) but this is likely an underestimate and modelling suggests that even these low numbers are sufficient to drive significant population declines (Crawford et al. 2017). Recreational gillnets are likely to have had an effect on the yellow-eyed penguin population, but are currently banned within coastal waters of up to 4 miles around the South Island (Crawford et al. 2017), excluding Rakiura, and as such, represent less of a threat. However, if this ban were lifted, this threat would be of similar magnitude to the large-scale gillnets that principally operate further out. Furthermore, fisheries activities appear to affect prey availability and prey quality (Mattern 2007; Browne et al. 2011), and influence penguin foraging behaviour (Mattern et al. 2013). Modelling has found a likely correlation between changing sea surface temperature and penguin vital rates, whereby productivity and survival are projected to decline under predicted climate change (Mattern et al. 2017). This has been seen in the Boulder Beach colony, where changes in SST have been found to account for 33% of the population fluctuations (Mattern et al. 2017).
Introduced ferret Mustela furo, stoat M. erminea, unleashed dogs Canis familiaris, and possibly feral cats Felis catus, are predators in the South Island. Predation by pigs Sus domesticus on the main Auckland Island and in the Catlins is known to occur (B. McKinlay per D. Houston in litt. 2012). A rogue female New Zealand sea lion Phocarctos hookeri and her daughter had been estimated to eat 20-30 birds annually on the Otago Peninsula (Lalas et al. 2007), but they have since died of natural causes. Accidental fires in breeding areas are a known, but infrequent, threat. Repeated adult die-off events remain little understood but might be due to toxins (Gill and Darby 1993). Disease appears to be a growing problem in some populations in most recent years, with diphtheritic stomatitis (caused by the bacteria Corynebacterium spp.) and the blood parasites Plasmodium spp. and Leucocytozoon tawaki, the latter formerly only known from Fiordland penguins, causes of mortality for chicks (Argilla et al. 2013, Gartrell et al. 2016). Human disturbance, particularly from unregulated tourists at breeding areas, negatively affects energy budgets, fledgling weight and probability of survival (McClung et al. 2004; Ellenberg et al. 2007, 2009, 2013), with human to penguin distance being a predictor of the likelihood of defensive behaviour (French et al. 2019).
Conservation Actions Underway
Conservation management projects are and have been undertaken in the South Island by or under New Zealand Department of Conservation (DOC) approvals. The Yellow-eyed Penguin Trust was formed to raise awareness and funds and now in conjunction with DOC undertakes predator control and coastal revegetation. Many mainland sites have been fenced to minimise disturbance by farm stock and to facilitate vegetation restoration. Predator trapping is intensive in many breeding sites. In 2019, a new recovery strategy commenced, set to last until 2024 (Te Rūnanga o Ngāi Tahu et al., 2020). Some sites subject to unregulated visitor disturbance are either closed during critical periods, or patrolled by volunteer wardens. Improved signage and visitor guidelines are promoted at key sites, but these tools are less effective at improving visitor behaviour than closure or strict regulation (Stein et al. 2010). Rehabilitation is undertaken at four mainland sites, including Penguin Place on the Otago Peninsula and Penguin Rescue in North Otago, to prevent losses due to starvation, injury and moult complications. There is a census of South Island colonies approximately every five years, and a census of selected sites annually (Taylor 2000).
Conservation Actions Proposed
Obtain reliable population estimates for the Auckland and Campbell Islands. Sustain and enhance predator control at mainland breeding sites and eradicate predators (pigs and cats) from the Auckland Islands. Quantify the impact of commercial fishing activity on yellow-eyed penguins (bycatch mortality in gillnets and the influence of bottom disturbance by trawling/dredging on penguin behaviour and food quality), and minimise the potential for interactions with gillnet fisheries, including through the creation of Marine Protected Areas. Regulate tourist access to breeding colonies. Develop a comprehensive understanding of the spatial and temporal extent of at-sea distribution during critical seasons (e.g. breeding, pre-moult, winter) and life-history stages (e.g. juvenile dispersal) to quantify fisheries overlap. Derive up to date data on important diet species throughout the range to evaluate changing patterns of foraging and diet, and assess the implications of climate change on marine productivity of relevance for the species. Recovery Plan revision is underway and should formalise regular monitoring of nest numbers and breeding outcomes at selected sites, and ensure maintenance of the quality of the Yellow-eyed Penguin Database.
65 cm. Medium-sized penguin with pale yellow eye. Pale yellow head with black feather shafts. Band of bright yellow from eyes around back of head. Juvenile has greyer head with no band. Similar spp. Distinctive from other crested penguins in range. Voice Slightly musical compared to other penguin species.
Text account compilers
Trathan, P. N., Clark, J.
Benstead, P., Ellenberg, U., Garcia Borboroglu , P., Hickcox, R., Houston, D., Lalas, C., Mattern, T., McClellan, R., McKinlay, B., Ratz, H., Seddon, P., Webster, T., Young, M., van Heezik, Y., Moreno, R., Martin, R. & Pearmain, L.
BirdLife International (2021) Species factsheet: Megadyptes antipodes. Downloaded from http://www.birdlife.org on 26/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/01/2021.