A census of the Snares crested penguin
In October 2000 the Southland Conservancy of the Department of Conservation (DoC) organised an expedition to the remote Snares Islands to census the breeding population of the islands endemic penguin, the Snares crested penguin.
While the Snares crested penguin is not considered to be at risk, populations of other crested penguins in the sub-antarctic appear to be declining and information from the Snares was needed to see if any management actions were required. While population estimates had been made at the Snares based on chick counts, a count of nesting pairs had never been carried out and the last chick count was done in 1987. The population was then estimated at 23,000 breeding pairs.
The expedition was lead by Jacinda Amey and included Gus McAlister, Alan Tennyson from Te Papa and myself.
The trip down
We left Bluff early on October 4th aboard the new NZ Navy frigate HMNZS Te Mana, which was assisting DoC with several projects in the sub-antarctic islands. Despite a reasonably rough sea, the 200km trip to the Snares was quite comfortable and we arrived off the islands in the late afternoon. Alan and I went ashore by rigid inflatable boat (RIB), along with several Navy personnel who assisted in getting all the stores to the hut. Jacinda and Gus stayed aboard Te Mana, having to travel to the Auckland Islands to band albatross chicks there before returning to the Snares.
After settling in, Alan and I set about looking for suitable colonies at which to monitor nest additions and losses. Snares crested penguins are synchronous breeders and our arrival had been timed to coincide with the end of egg laying, when the maximum number of pairs attempting breeding would be present.
Some pairs attempted to begin nesting during our stay, but these were nearly all unsuccessful, while others who lost their eggs abandoned their nests. By monitoring nest numbers at some sites, we would be able to fairly compare those colonies counted at the beginning of our stay with those counted two weeks later.
Four monitoring colonies were chosen, 2 small and 2 large. All the nests were counted in the small colonies, while a sample of 100 nests was made in the large colonies. Maps of nest locations were made and painted sticks used as markers, but identifying just which nest was which proved to be a vexing problem, particularly in the larger colonies. The fact that some pairs gradually moved their nests away from their closest neighbours meant that maps needed frequent revision!
Jacinda and Gus arrived early on the morning of October 9th, Te Mana having been delayed a day by poor weather around the Auckland and Campbell islands. Despite not feeling the best after a rough voyage, Jacinda and Gus were keen to have a look at some penguins and we set off to do the monitoring rounds and start counting colonies.
The first few large colonies took a long time to count, as we could not agree on numbers. We wanted a minimum of 2 counts per colony and for them to agree within 5%. After a bit of practice, we all got better at counting and used stringlines or paint markers to break up large colonies into more manageable areas. Details of colony size, shape and vegetation were also recorded along with a GPS reference.
Alan Tennyson, who taken part in the last chick count in 1987, proved to be invaluable at interpreting the old colony maps and navigating around the island. Relocating some colonies was a difficult task, as some had vanished and others had merged. Several new colonies of up to 480 pairs were also found.
Nice work, if you can get it
Most people think that working with penguins would be "nice". Those that do obviously haven't been to the Snares! The forest is a tangle of half-fallen trees that is hard to move around in and is good at ripping your clothes to shreds. Underfoot, there are titi burrows that, if you put your foot in the wrong place, collapse without warning. Many of the penguin colonies are in vegetation recently killed-off by the penguins activities and with abundant mud underfoot. The penguins themselves protected their nest sites by biting any human legs that got too close - fortunately canvas gaiters shielded us from all but the most well aimed pecks. Ear plugs soon proved essential, as the sound of hundreds of penguins screaming out their displeasure at our presence was ear-splitting!
It was hoped that nearby Broughton island could be visited during the trip. It was intended that DoC's boat MV Renown would come down from Doubtful Sound in Fiordland to pick us up and, if the weather was favourable, drop us on Broughton for a couple of days before returning us to Bluff. Unfortunately, bad weather forced the Renown to seek shelter at the Southern tip of Stewart Island and then return to Bluff when one of the crew was injured. On Oct 24th, the much faster Southern Express, a 20m catamaran, arrived to pick us up. A stiff easterly wind made loading a wet affair, and forced us to travel "the scenic route" home, around the west coast of Stewart Island, however clipping along at over 20 knots, it took only 6 hours from the Snares to Bluff.
A total of 25,861 breeding pairs were counted on the main island. This, combined with the estimated 4,000 pairs on Broughton island, gives a total of near 30,000 breeding pairs and indicates that the population is not in decline. No management action for the Snares penguins is thus currently necessary, but another census should be carried in around 10 years time.
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