Richdale book

Microchips used to ID penguins

Transponders, first used by the Trust on Stewart Island in 2005-06, are now used on all our reserves.

A tiny microchip embedded in glass is inserted under the skin with a needle, often at the back of the neck. Transponders are widely used for cats and dogs, farm animals and wild animals, including various penguin species. The transponder is a passive tag and is scanned using a handheld or wand reader.

In the past, the Trust has assisted the Department of Conservation with marking penguins, using stainless steel flipper bands, on its Tavora and Otapahi reserves. The bands have been suspected of causing injury through abrasion and entanglement, and also of negatively affecting foraging performance of some individuals and penguin species. Additionally, they require ongoing checking and maintenance. Debate on the possible impact of flipper banding continues in the scientific literature. Read the rest of this entry »

Royal Society of New Zealand Awarded Teaching Fellow – Jim Young

Jim Young, a teacher from Catlins Area School and a recipient of a Royal Society of New Zealand – Awarded Teacher Fellowship, spent 2010 working at Long Point. Jim ‘s project, ‘Whakaora Irahuka: restoring the white cliffs’, investigated aspects of seabird restoration at Long Point/Irahuka. This included surveying and mapping seabird habitat, establishing vegetation plots, examining predator species composition and abundance, and surveying the lizard fauna and distribution.

Jim returned to the classroom in 2011 with “an increased knowledge of local ecology and methodology and how to involve students”.

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Codfish Island surveys 2001-2012

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Auckland Islands trip 2009

The Auckland Islands, at latitude 50 degrees south, are the largest of New Zealand’s subantarctic islands, with over 500 km of coastline, much of it steep and inaccessible to penguins and people, particularly on the exposed western side. Uninhabited now, the main island was once farmed by a hardy few, whose legacy is feral cats and pigs. Surprisingly, rats have never managed to colonise the islands.

Visiting the islands between 6 November and 7 December 2009 were team members Leith Thomson and Sandy King (both representing the YEPT), Jo Hiscock (team leader, DOC), Jo Ledington and Callum Lilley (DOC), and Kate Beer (Wildlife Management student from the University of Otago). The Trust contributed to the cost of transport and accommodation provided by Henk Haazen on his 15m yacht Tiama. Crew member Steve Parsons completed the team of eight.

Almost 200 km of coastline was surveyed, with identification of 301 landing sites. These were regarded as a minimum because some sections of coast accessible to penguins couldn’t be surveyed because of sea conditions. Most landing sites would be used by one or more pairs, though probably some would be used by non-breeders.

The pig- and cat-free islands had more landing sites per kilometre of coast surveyed than the main island, which raises questions about the impact of these animals on yellow-eyed penguin and other ground-nesting birds. Areas of the main island adjacent to these islands - the northern shore of Carnley Harbour, and Port Ross and northern harbours – also had a higher number of landing sites than the coast in the middle of the main island. This suggests that perhaps the predator-free islands act as reservoirs whose overflow sustains the population.

Does Leith need some sea lion training lessons from John??

Left to right: Jo Hiscock, Sandy King, Leith Thomson, Kate Beer, Jo Ledington, Henk Haazen, Steve Parsons and Callum Lilley.

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GPS data loggers

Despite many studies on yellow-eyed penguins we know little about their habits at sea – their foraging patterns and where they are feeding and travelling. Interpretation of the species’ population dynamics, and consequently conservation measures, are primarily based on what can be observed on land. Today with the aid of modern satellite technology, studying penguin behaviour at sea through miniature GPS logging devices attached to their backs has opened a new window of opportunity to examine all aspects of the penguins’ biology. Read the rest of this entry »

Unexplained chick losses on Stewart Island

The Yellow-eyed Penguin Trust has just completed the first year of a planned five-year study to measure the effects of cat predation on yellow-eyed penguins on Stewart Island’s north-eastern beaches. But instead of cat predation, what we found was an, as yet unexplained, high chick death rate.

Because of an apparent decrease in yellow-eyed penguin numbers on Stewart Island, the Trust, assisted by the Department of Conservation (DOC), was testing whether the loss might be attributed to predation by feral cats. During the 2003/2004 breeding season all nests along the Mt Anglem coastline were monitored intensely.

Early in the breeding season we discovered that chicks were dying at an alarming rate. Of 42 chicks hatched, only 11 were still alive by mid-February. This is a survival rate of just 26%. At some beaches every chick died.

There were no signs that these deaths were due to cat predation; instead starvation appeared to be the most likely cause of death. This possibility was tested by comparing the weights of yellow-eyed penguin chicks from the offshore islands of Bench, Tommy and Whenua Hou (Codfish) to those in the study area/main island.

Although the weights of chicks on the offshore islands were on average lower than those on the Otago Peninsula, the weights of the surviving chicks in the research area were comparable.

Observers monitoring the penguin chicks noted large pieces of regurgitated fish beside some of the dead chicks. Could this be a repeat of the mystery disease or biotoxin that killed off a significant proportion of the breeding population on the Otago Peninsula in 1989-90, or a widespread shortage of food?

At the moment we have lots of unanswered questions, although we’re hoping there may be some partial answers when analyses of samples and autopsies are completed.

These results highlight the importance of regular, ongoing monitoring of our penguins. “If the Yellow-eyed Penguin Trust had not been on Stewart Island this summer, we would never know this event had happened. The Department looks forward to working with them to determine what is actually happening with these birds and if there is anything we can do about it,” says Brent Beaven, DOC Programme Manager – Biodiversity, Stewart Island.

The Trust had already committed in principle to a five-year programme on Stewart Island, subject to finance being available. Although we feel it is important that our monitoring continues, we have not as yet been able to find total funding. This year’s work was largely funded by two, unexpected one-off grants. One was from the Community Trust of Southland, and the other from Contact Energy, as a result of Otago people using 10% less electricity to ensure adequate power supplies during early winter 2003. If you would like to consider helping fund this research, any donations marked Stewart Island Project will be earmarked for next season’s work.

Feral cat study on Stewart Island

Despite the fact that the first year of our study into the effects of feral cats on hoiho populations on Stewart Island did not show high rates of predation, we still managed to obtain some useful data.

Grant Harper’s research in an inland forested area on Stewart Island in 2002 found that the average weight for male cats was 3.4 kg and for females was 2.6 kg. Sandy King found almost identical results in the coastal yellow-eyed penguin habitat during our study this season: males 3.4 kg and females 2.5 kg.

However, the two studies differed in what food the cats appeared to be eating. Rats made up 60% of the diet of cats in the inland area, with birds making up 19% and invertebrates 15%. On the coast, rats and possums accounted for only about 30% of the diet, with beetles making up another 10%. Interestingly, 27% of the stomachs were empty. Thankfully this season there is no evidence of yellow-eyed penguins in cats’ diet.

This year no cat predation of chicks was seen. Our previous experience in Otago suggests that predation events may be sporadic and sometimes only occur every 2-3 years. The long-term monitoring that we have instigated will, over time, tell us to what level feral cats are affecting yellow-eyed penguin breeding success.

Cat predation on Stewart Island

Three years of census work by the Yellow-eyed Penguin Trust has suggested that penguins may be in decline on Stewart Island. The cause and rate of this decline are not known, but feral cats are suspected to play a role because they are the only land-based predator on Stewart Island large enough to kill a penguin. The decline does not appear to be food related, as surveyed pest-free islands have healthier penguin populations.

Feral cats on Stewart Island were introduced from Europe. Early European settlers brought cats to New Zealand from 1769 onward, as a control agent on rat infested ships. However, it may have taken around fifty years for a feral population to become established on the mainland. Ships have visited Stewart Island since 1804, and in 1909 Cockayne reported cats to be “common”.

There is no evidence that they grow any larger than cats which live in a domestic setting. Male cats on Stewart Island average 3.4 kg and females 2.6 kg. Cats are efficient predators and hunt diurnally and nocturnally. They will live in almost all habitats. Their diet is composed mainly of rats (60%), although birds (19%) and invertebrates (15%) together compose a significant portion.

This research proposal covers a five-year study into whether the control of cats has a positive effect on the breeding success of yellow-eyed penguins on Stewart Island. One area will have as many cats killed as possible and another will be left as a control area. We are hopeful that this will show us that the fledging success in the targeted area is greater.

The Yellow-eyed Penguin Trust is seeking funding for a five-year study into the impact of cats on yellow-eyed penguins. The funding for year one has been guaranteed by the Yellow-eyed Penguin Trust (thanks to our unexpected donation from Contact Energy) and this will take place October 2003-March 2004. The project will again be supervised by our Projects Officer, David Blair.

Stewart Island breeding locations revisited

Three seasons after a comprehensive nest census on the north east coast of Stewart Island, it was deemed useful to revisit three breeding locations to see if the numbers compared with the earlier visit, and to look carefully for juvenile yellow-eyed penguins – an indication of breeding success.

The Project Officer took four volunteers along to get first hand experience of the work, to do those long hours of beach counts, and to learn about crawling through vines and penguin poo to locate nests.

There were seasickness, large rats, and enough equipment and food (but no meat as someone inadvertently left it in a fridge at Halfmoon Bay) to outlast a week of storms. The weather was great, and the early 5 am starts thrilling. The results were somewhat predictable with the indication of a similar number of breeding pairs as last time, but ominously no juveniles were identified on or near any of the beaches we surveyed.

The Trust hopes to support research into the relationship of feral cats and the yellow-eyed penguin breeding locations in the future.