Yellow-eyed penguin (YEP) Investigation

Stewart Island - November 2007

 

Yellow-eyed penguins (Megadyptes antipodes) (YEP) are the world’s rarest penguin species, and are only found in New Zealand - on the Otago peninsular and the south-east coastline of the South Island, Stewart Island (and some its off-shore islands), and the sub-Antartic islands (Auckland Island group).

 

Yellow-eyed penguin photographed at Golden Beach, Stewart Island

 

During the current and previous four breeding seasons (November – February), YEP Trust volunteers have been monitoring nesting sites on the northern and north-eastern Stewart Island coastline, due to concerns about chick mortality. Last year (2006), of 32 chicks monitored, none survived to adulthood. Thirty-one of the chicks died between the ages of 7-14 days after hatching, and only one survived to almost fledgling stage. Investigations by Maurice Alley, Massey University, revealed diptheritic conditions around the beak and nares of some of the chicks from which Corynebacteria were cultured, and some evidence of leucocytozoan, a blood parasite.

 

A team of four of us - Graham Mackereth, Veterinarian, MAF Biosecurity New Zealand, Kate McInnes, Veterinarian, Department of Conservation, Rachel Cane, Entomologist, NZ Biosecure, and myself - assembled at Oban, Stewart Island on 21 November 2007, to investigate chick mortalities in the Stewart Island population.

 

Half-moon Bay, Stewart Island

 

Deep Bay, Stewart Island

 

On 22 November 2007, we were ferried by the DOC ship ‘Jester’ to Golden Beach, to meet up with Joanne Wright, one of the YEP Trust volunteers. She was monitoring 5 nests at this beach. At the time of our visit, there had not been any chick deaths here, although some of the chicks had only recently hatched.

 

Stewart Island showing some of the locations visited

 

‘Jester’, the DOC ship

 

Yellow-eyed penguin on Golden Beach, Stewart Island

 

Yellow-eyed penguin and recently hatched chicks, Golden Beach

 

YEP nest 2-300 m above the beach in bush or scrub, with the nest a shallow bowl lined with sticks and forest debris. YEP pairs typically lay 2 eggs. Both parents share the job of rearing the chicks. For the first few weeks after hatching, one adult stays with the chicks, the so-called ‘guard phase’, whilst the other feeds, until they are large enough to be left alone. The chicks should put on weight rapidly, and ultimately should get as large as the parents by late January, early February.

 

On 24 November 2007, we were flown by helicopter to Yankee River, on the remote northern coast of Stewart Island.

 

Squirrel helicopter that transported us to Yankee River

 

Yankee River, Stewart Island

 

We were met by Sandy King, one of the YEP Trust volunteers who had brought us a recently dead chick from East Smoky Beach. The chick was very thin, and grossly had no visible pathology.

 

Dead chick from East Smoky Beach, Stewart Island

 

East Smoky Beach chick

 

Later that afternoon, Rachel set up some insect traps to try and capture some mosquitoes and some of the numerous sandflies, to test for vector borne disease agents.

 

The following day, we walked to East Smoky Beach, to check out the nest site and look for ticks or other insects in and around the nest site.

 

Sandy King, YEP Trust volunteer, crossing Yankee River

 

East Smoky Beach, Stewart Island

 

East Smoky YEP nest

 

Searching for ticks and other insects

 

That evening, we were stranded at Yankee River hut, as the sea was too rough to be picked up by the water taxi.

 

Rough seas at Yankee River

 

Meanwhile, it gave us time for some photo ops and search for Fjiordland crested penguins, which also inhabit this coastline.

 

Yankee River

 

Yankee River

 

Fjiordland crested penguin on rocks at Yankee River Beach

 

Fjiordland crested penguin nest. Notice large healthy chick on left.

 

Sunday afternoon, Kate McInnes turned up with two dead chicks from a nest at Long Harry Beach.  These were very similar to the dead chick from East Smoky we had post-mortemed a couple of days previously. As before, a thorough post-mortem was conducted and samples collected for virology, bacteriology, histology, serology and blood smears for haemo-parasites. Noticeably the gizzards were virtually empty.

 

Empty gizzard in Chick 1 from Long Harry

 

Eventually we were picked up by water taxi from Yankee River, and ferried back to Half-moon Bay.

 

Kate McInnes getting into a dinghy at Yankee River

 

While staying at Oban, we were visited by friendly kaka, and I had an opportunity to visit Ulva Island, a pest-free sanctuary.

 

Kaka at Oban, Stewart Island

 

Stewart Island Robin on Ulva Island

 

On Monday 26th November, Graham Mackereth and I left Stewart Island. I carried samples for the respective labs at IDC-Wallaceville and Massey University. Hopefully, the lab test results will provide some of the proof for what is killing the YEP chicks.

 

Acknowledgements

 

I gratefully acknowledge Biosecurity New Zealand and the Department of Conservation who paid for the travel and accommodation costs, and AsureQuality Limited who sponsored my time. I would also like to thank H.E.Perry who kindly loaned some of the Olympus E-system lenses used on the trip, in particular the fabulous ZD 50mm f2 macro lens, which was used extensively to photograph the YEP in often dark, wet conditions, and document the chick post-mortems.

 

Robert Sanson

5 December 2007