Species Focus: Yellow-Eyed Penguin

Yellow-eyed penguin

This is the first in a new series of blog posts that will focus in on the conservation of some of the world’s less well known species, animals that are not particularly famous amongst the general public but who need urgent conservation attention. The posts will give some background on the species and then focus in on the conservation challenges they face and the efforts being undertaken to conserve them. The first species placed under the spotlight is the beautiful and charismatic yellow-eyed penguin.

Yellow-eyed penguin, © Chris Ruis

Species profile

The yellow-eyed penguin is endemic to the dramatic coastlines and churning seas of New Zealand, where it is found in the southeast portion of the South Island and on Stewart Island and the subantarctic Auckland and Campbell Islands. It’s a species with a rather descriptive scientific name: Megadyptes antipodes translates roughly as ‘large diver of the southern islands’. And the Maori name for this species also captures some of its essence: hoiho means ‘noise shouter’, a reference to their loud, shrill call and tendency to let it be heard.

Distribution of the yellow-eyed penguin. Endemic to New Zealand, this species is found in the South Island, Stewart Island and Subantarctic Auckland and Campbell Islands (brown areas). Modified from the distribution map on IUCN.

The yellow-eyed penguin stands at up to 80cm tall, making it the fourth largest penguin species on the planet. They display the contrasting black back and white underside typical of penguins. This ‘cryptic camouflage’ hides them from predators in the water, whether the predator is looking down from above (where the black back blends in with the dark water below) or up from below (where the white belly blends in with the light above). And there are plenty of potential predators in the sea, from sharks and barracouta to fur seals and the New Zealand sea lion. The most striking part of this penguin, though, is a strong yellow stripe which streaks backwards from each eye and around the head. Additional yellow feathers surround the eye and beak and the beady eye itself is also yellow.

 Yellow-eyed penguins display the black back and white underside characteristic of penguins but their most striking feature is a yellow streak that connects the yellow eyes round the back of the head and yellow feathers around the eye and beak. Top image - © Tony Whiethead, source NZBirdsOnline, Lower image - © Chris Ruis

Yellow-eyed penguins are not typical penguins. We (or I at least) tend to think of penguins as sociable animals, living in large, noisy groups. Not the yellow-eyed penguin. They’re far more antisocial. They make their nests in vegetation within forest or shrubland and typically choose a secluded site, often bounded on one side by a bank, log or tree. And the nest site is almost always out of view of any of their fellow penguins. Courtship begins in August when partnerships (which are often long-term) form or reform. They also choose their nest site in this month before eggs (typically 2) are laid in September-October and hatch in November-December. For the first 40 days or so after hatching, the parents are in guard mode where one parent stays at the nest to guard the chick while the other heads out to sea to forage. The yellow-eyed penguin is mainly piscivorous and uses its excellent eyesight to catch a variety of fish, including silverside, squid, aruhu, sprat and red cod. They’ll swim as far as 50km from the shore in search of food and can dive up to 160m from the surface to reach the seafloor. Returning to the nest with their catch, the parents greet one another with an elaborate series of trills and calls before the chick(s) is fed a regurgitated soup of fish and squid. Once the chick(s) reaches 6 weeks of age, both parents go out to forage in an attempt to satisfy the voracious hunger of the youngster before fledging occurs several weeks later.

Potentially the most dangerous time of year (for adult yellow-eyed penguins at least) is the moult which lasts 3-4 weeks and begins in February for juveniles and March/April for adults. During this period, the entire set of feathers are moulted, meaning the birds are not waterproof and so cannot enter the sea to feed. Clearly, growing an entire set of new feathers requires a lot of energy and as the birds are not able to eat during this time, they can loose up to 4kg in weight, which isn’t far off 50% of the total body weight. This period carries a real risk of starvation, dehydration or predation.

Penguins are popular birds and in 2007 it was estimated that nature-based tourism brought in $100 million annually to the Dunedin economy. And this figure is likely to have increased over the past decade. The yellow-eyed penguin is a major component (if not the major component) of nature tourism in this area. People can pay to see these penguins with money featuring the yellow-eyed penguin itself, as this species is found on the reverse side of the New Zealand $5 bill.

Conservation challenges

The yellow-eyed penguin is currently classified by the International Union for Conservation of Nature (IUCN) as Endangered. There’s thought to be roughly 3400 mature individuals around New Zealand, but this figure has decreased from 7000 in the year 2000 and is thought to still be decreasing. The number of breeding pairs on the New Zealand mainland was at its lowest in the 1990-91 season when an estimated 150 pairs bred on the South Island. Following this, there was a steady increase to roughly 600 pairs in 1996-97. Since then, numbers have fluctuated somewhat, but the previous 3 years have seen the lowest number of mainland breeding pairs since the early 1990s. And the population is fragmented, which means small groups of individuals live in isolated groups that are more liable to extinction.

 IUCN classification of the yellow-eyed penguin. Penguin image © Craig McKenzie, source NZBirdsOnline

Mainland breeding pairs of yellow-eyed penguin from 1980-2018. Following a low of roughly 150 pairs in the 1990-91 season, the population increased but has fallen again recently to its lowest level for 27 years. Data source - Yellow-Eyed Penguin Trust

The yellow-eyed penguin relies on the mainland for nesting, roosting and moulting and relies on the sea for feeding. Therefore this species is affected by both terrestrial and marine stressors. Introduced mammalian predators are a sporadic but significant threat to this species. New Zealand does not have any native terrestrial mammals (bats and marine mammals are the only native mammals on these islands) but a myriad of such species have been introduced by humans. Ferrets, feral cats and, in particular, stoats have had a devastating impact on many native species. Adult yellow-eyed penguins are potentially too large to be taken by these species but chicks are highly vulnerable, particularly 5-20 days after hatching, despite their parental guard. And eggs make an easy meal if left unguarded. Pigs have also been recorded to kill yellow-eyed penguins. Domestic dogs let off the lead in penguin habitat can also kill individuals, as highlighted when 2 yellow-eyed penguins were killed by dogs at a nature reserve in the Catlins in May this year, despite clear signage that dogs are not allowed in the area.

Mass mortality events in adult yellow-eyed penguins are not yet fully understood. However, infectious diseases are thought to play a role in such events and are known to kill individual penguins. Avian cholera, avian pox and Newcastle disease virus have been implicated in mass mortality events. Avian malaria is also a potential danger for these penguin populations due to an increase in the insect vectors that transmit this pathogen. Exposure to toxins within the marine environment may also result in the death of a large number of individuals.

Human disturbance through tourism or recreation within yellow-eyed penguin habitat not only causes significant interference at breeding sites but also increases stress levels and heart rate of the birds. Another human-induced factor that has the potential to cause catastrophic losses is climate change. A single scrub fire killed more than 60 adult yellow-eyed penguins in the Catlins in 1995 and a warming climate increases the risk of such fires.

The challenges for the yellow-eyed penguin don’t cease when they enter the water. It is estimated that 44 yellow-eyed penguins are killed annually through bycatch (95% confidence interval 17-90 individuals). This is mostly through bycatch in sea nets, but trawler bycatch has also been recorded. The impact of fishing was highlighted by surveys on Codfish Island which found the number of yellow-eyed penguin nests decreased from 24 in 2016 to 14 in 2017. The adult birds missing from these nests are known to have disappeared at sea and drowning in nets from a fishery within the nearby foraging area is strongly suspected. Crucially, only a vanishingly small proportion of commercial trawlers have historically had independent observers on board, meaning bycatch deaths may have been under-reported. While some foraging areas are covered by fishing exclusion zones, many are not.

It is not currently clear whether fisheries compete with yellow-eyed penguins for their prey. Yellow-eyed penguins predominantly catch small juvenile fish that are typically smaller than those that are targeted by fishermen. However, larger fish will be taken by this species, so there is the potential for some overlap. Additionally, fisheries can alter the distribution of ages or sizes of fish and overfishing can alter the marine ecosystem, which may reduce the food availability for penguins. As yellow-eyed penguins regularly forage near the ocean floor, the degradation of this ecosystem by commercial oyster dredging may remove areas of suitable habitat.

There is a currently unproven link between an increase in ocean temperatures and a reduction in penguin vitality, raising concerns that rising ocean temperatures due to global warming may have a detrimental effect on these species. Penguins can also be exposed to pollutants that are released on land but end up in the sea through sewage effluent or water run-off.

Efforts for preservation

All-in-all, its fair to say that the yellow-eyed penguin is facing quite an array of threats to its survival, particularly given its dependence on both the terrestrial and marine environments. However, a similar array of conservation efforts are currently being undertaken to try to alleviate the threats discussed above and to therefore ensure the preservation of this species.

The Yellow-Eyed Penguin Trust and the New Zealand Department of Conservation (DoC) are at the forefront of the efforts to save this species. An extensive program of habitat conservation has seen numerous native trees and shrubs planted to provide additional suitable penguin habitat. This is particularly important to provide the hidden-away nesting sites favoured by this species. Such planting doesn’t just provide benefits for the yellow-eyed penguin, but provides habitat for other terrestrial and marine species. Predator trapping is currently taking place as part of a nationwide effort to preserve native species.

Penguin rehabilitation is also playing a major role in attempts to boost the population of this species. Individuals that are injured (through unsuccessful predation attempts or other factors), exhibit signs of disease or are underweight are temporarily taken into rehabilitation centers where they can be nursed back to health before being released back into the wild. Several veterinary hospitals in Dunedin and Oamaru provide veterinary care before the penguins are transferred to one of four rehabilitation facilities. Penguin Place, Penguin Rescue and the Oamaru Blue Penguin Colony provide the facilities in Otago and Christchurch Penguin Rehab does so in Canterbury. With a species as rare as this, every individual is vitally important.

I was lucky enough to visit Penguin Place, located just outside Dunedin, in February this year and see some of their excellent work first hand. This center combines a penguin rehab hospital with a private conservation reserve, so has penguins both in rehab and wild-living in the same reserve. Penguin Place is the world’s first conservation programme that is funded entirely by tourism, with guests paying for a guided tour of the reserve. And the tour is brilliant. You walk through a series of trenches that have regular viewing holes, enabling close views of the penguins without disturbance. When we visited, breeding season had finished and there was only a single wild yellow-eyed penguin chilling out on the reserve (more would have returned from fishing to roost in the evening). But we had good views of her. And its not just the yellow-eyed penguins that are catered for here. Nesting boxes are provided for little blue penguins, which were present in good numbers when we visited, and other penguin species are cared for in the hospital as well. Several erect-crested penguins accompanied the yellow-eyeds on our visit. The reserve also provides good habitat for non-penguin species, exemplified by a hulking New Zealand sea lion hauled out on the beach.

The rehabilitation area at Penguin Place Conservation Reserve. A mixture of yellow-eyed penguins and erect-crested penguins were in the hospital when we visited © Chris Ruis

An erect-crested penguin in the Penguin Place rehabilitation center © Chris Ruis

A yellow-eyed penguin in the Penguin Place rehabilitation center © Chris Ruis

Overlooking the Penguin Place Reserve where wild-living yellow-eyed penguins live and breed © Chris Ruis

The Yellow-Eyed Penguin Trust and DoC also publish guidelines for viewing penguins to attempt to keep conflicts to a minimum.

While the terrestrial threats to yellow-eyed penguins are relatively well understood, understanding of marine threats is lagging behind. The interaction of yellow-eyed penguins with the marine environment is therefore a key focus of current research efforts. Key research targets include:

·      Understand the cause of mass mortality events so they can be mitigated in the future

·      Understand the current diet of the yellow-eyed penguin to determine overlap with fisheries. Previous data on diet come from the 1980s and 1990s and diet may have changed more recently

·      Understand the impact of bycatch on penguin populations. An increased number of observers are being deployed to commercial fishing boats

·      Understand the impact of bottom fisheries and oyster dredging on the yellow-eyed penguin

There’s still some way to go before the range of threats affecting the yellow-eyed penguin will be fully understood. And therefore it will be some time until these threats can be fully mitigated. However, the combination of habitat creation and habitat preservation will provide these penguins with the nesting sites they need to thrive. And the fantastic work of the penguin rehabilitation centers should ensure that every penguin that can survive does so. These cumulative efforts provide real hope that the population of this declining and emblematic species will stablilise and then begin to increase in the future.

Read more

If you’d like to read more about the yellow-eyed penguin or support one of the charities mentioned above, these links may be useful:

Yellow-Eyed Penguin Trust website - https://www.yellow-eyedpenguin.org.nz/

Penguin Place Conservation Reserve website - http://penguinplace.co.nz/

New Zealand Department of Conservation website - https://www.doc.govt.nz/

A report on the current understanding of threats to the yellow-eyed penguin - https://www.yellow-eyedpenguin.org.nz/app/uploads/2018/06/YEPT_The-pathway-ahead-for-hoiho-February-2018.pdf

An excellent Guardian article on efforts to save yellow-eyed penguins - https://www.theguardian.com/environment/2018/mar/12/yellow-eyed-penguin-photo-essay-murdo-macleod