Yellow-eyed Penguin, Plodding, Plucky, Persistent.

Forest and Bird, Issue 303, 1 February 2002, Page 20

Yellow-eyed Penguin, Plodding, Plucky, Persistent.

NEVILLE PEAT

More than 10 years of intensive effort has kept the yellow-eyed

penguin on the New Zealand mainiand,

reports.

t the remote kakapo stronghold of Whenua Hou/Codfish Island off the northwest coast of Stewart Island, a Department of Conservation ranger happened upon a yellow-eyed penguin at its nest last spring. These hoiho are known to inhabit Whenua Hou so there was nothing unusual about this encounter — except for the nest’s location. It was about a kilometre from the sea and 130 metres above it. Yellow-eyed penguins habitually nest in coastal forest or shrubland, sometimes a good distance from the sea. They will go to extraordinary lengths to find a site that is physically suitable (usually with something solid like a fallen tree behind it) and private from other nesting

‘yellow-eyeds’. A kilometre inland appears to be about their limit. Fair enough. A kilometre is a long way for a seabird to walk. Just think of the cost in time lost fishing at sea and energy expended getting to and from the nest. In the case of the Whenua Hou pair, they were assisted by tracks cut for kakapo management. More than anything, this example of inland nesting helps illustrate the pluck and plodding persistence of the species.

Other indicators of fortitude include: an ability to scale forbidding cliffs, penetrate dense undergrowth or cope with degraded habitat, while raising two chicks a year in the face of — for most mainland birds anyway — a gauntlet of predators, including dogs, feral cats, ferrets and stoats. Not to mention occasional upheavals in the food supply. On the mainland we have thrown at them a whopping range of impediments and still they survive, mostly along the coast of Otago Peninsula at Dunedin and the Catlins in southeast Otago. The yellow-eyed penguin (or Megadyptes antipodes, meaning big southern diver) is hardy to say the least. Behaviourally and biologically, hoiho is sufficiently distinct from all other

penguins to justify a genus to itself. There are six penguin genera altogether, found from the Galapagos Islands to Antarctica. Hoiho is the largest temperate-zone penguin -70 centimetres tall and up to about seven kilograms in weight. Scientists have dubbed it the ‘most generalised’ of the penguins — meaning that is, the most closely related to ancestral members of the family. Unique to New Zealand, the yellow-eyed penguin breeds from Banks Peninsula to subantarctic Campbell Island. The species comprises only a couple of thousand breeding pairs, making it one of the world’s rarest penguins. A revised ‘hoiho recovery plan, newly published by the Department of Conservation, paints a picture of cautious hope and sleeves-rolled-up determination. Certainly the yellow-eyeds are doing all they can to help themselves. The plan describes this penguin as ‘intrinsically robust ... with a high reproductive rate compared to other sea eee oeoeoeee-EE

birds and substantial longevity. The revised plan has dropped the former population target of 500 breeding pairs for the Otago Peninsula and Catlins populations. Instead, it now aims to ‘protect areas of habitat to allow for an increase in population. The nine objectives are all couched in general terms, although under an objective to protect hoiho chicks from predators, the actions include a target of protecting 50 percent of all South Island nests from predators. The plan’s principal author, Bruce McKinlay, who is based at DoC’s Otago Conservancy office in Dunedin, says the old ‘500 target’ was based on the theory that to be self-sustaining and genetically healthy a population required 500 pairs. The 1997 population estimate for the

South Island — the latest quoted in the plan — is 300-320 pairs. Bruce McKinlay says people are getting used to the fact yellow-eyed penguin populations will tend to fluctuate naturally, as documented by studies of the mainland populations over the past 20 years. Big crashes, however, can appear very scary if not catastrophic. In 1990, adult hoiho died in droves from something mysterious. A biotoxin in the food chain was suspected but never identified. Avian malaria was also postulated but never confirmed. By the time the epidemic was over, the mainland population had been halved. Just 130 breeding pairs were left on the Otago coast. Researchers in the subantarctic reported similar losses there. Hoiho’s ‘robust’ reputation relies on birds reaching their potential of a long breeding life and a good age. To date the longevity record is 21 years, set by an Otago Peninsula bird. Many of the larger seabirds are content to raise one chick a year whereas yellow-eyed penguins try to fledge two chicks (see box). ‘The best safeguard for the species is for the good breeders to survive to the next season, says McKinlay. DoC considers the species threatened. The international conservation body, the IUCN, recently reclassified the yelloweyed as ‘endangered’ (formerly ‘vulnerable’) a more at risk classification. Endangered is defined as ‘facing a very high risk of extinction in the wild in the near future’. That may seem too alarmist a view given the ‘robust’ tag and the populations quoted in the recovery plan, with over 1000 pairs estimated for Campbell Island and the Auckland Islands. Stewart Island is an important base for these penguins, lying as it does between between the subantarctic islands and the mainland. But the recovery plan’s ‘sceptical’ estimate of 470 to 600 pairs on Stewart Island is too optimistic. Surveys conducted in 1999 and 2000 on the main island by the Yellow-eyed Penguin Trust with DoC support counted 126 nests. Another survey last November on Whenua Hou/Codfish came up with 65 nests, giving a total for ‘Stewart Island’ of just on 200. Even if such a tally has to be considered a minimum figure, and excludes the Titi (Muttonbird) Islands, it is still a long way short of the recovery plan’s stab at an estimate. The count for Whenua Hou compared to the much larger main island is telling. It suggests the predator-free and Nature

Reserve status of Whenua Hou benefits the penguins. On Stewart Island itself, feral cats are thought to be devastating for chicks. The survey last spring also reported an impressive number of young birds coming ashore at Whenua Hou. Modern surveys of Stewart Island began in 1984 when an Otago Museum zoologist, John Darby, counted some 130 pairs and concluded that cat predation

was a major problem for the yellow-eyed penguins there. When he started systematic research of the yellow-eyed populations on the mainland in 1980, John Darby tramped the Otago Peninsula and Catlins coasts to the south. He recalls an almost total absence of areas managed or protected for hoiho. He was appalled at their plight. ‘There was really only one reserve

covering penguin habitat — Sandfly Bay on Otago Peninsula — and that had stock from neighbouring farmland through it, he says. ‘People were still shooting penguins, and cats and ferrets were taking a big toll.’ Today the picture is vastly different. Incremental habitat loss has been halted. All major breeding areas have been protected and some have been revegetated. Predator control work has improved chick survival in a number of areas. Monitoring is intensive. ‘There are more penguins now than when I started studying them 20 years ago, says John Darby, ‘but they remain at risk and we’re always going to have to manage the mainland populations. Early on, he investigated whether the mainland colonies were supplemented by migrants from the subantarctic strongholds. DNA studies showed the populations did not overlap, however. The mainlanders were on their own. In an earlier generation, Lance Richdale put the yellow-eyed penguin on the scientific map with his pioneering studies, which spanned 18 years, starting in 1936. He did not name his study areas in his published work and for many years modern comparisons were impossible. Then in 1987 an unpublished work of Richdale’s was discovered in Dunedin’s Hocken Library — possibly the draft of a PhD thesis but no one knows for sure — and suddenly the 1930-40s counts could be compared to those at the same beaches in the 1980s and 1990s. This has enabled John Darby, who has now studied yellow-eyed penguins longer than the legendary Richdale, to declare the species better off than for decades — but some way from being secure. Both he and Bruce McKinlay acknowledge that efforts by DoC, the Yellow-eyed Penguin Trust, Forest and Bird, and others, to protect the penguins, have benefited coastal conservation at large. Predator control for the penguins also helps safeguard species such as blue penguin and jewelled gecko, while habitat enhancement is a bonus for everything, including human enjoyment.

NEVILLE PEAT of Dunedin has written The World of Penguins, and Coasting — The Sea Lion and the Lark among numerous other books of New Zealand natural history. He chairs the biodiversity committee of the Otago Regional Council.