Winter on Macquarie Island (or Macca as it is often referred to) is very different to summer. When the last ship of the season departs in March it’s not just expeditioner numbers that decrease. Many of the animals also begin to depart. Agreeing with summer expeditioners that winter is too wet, cold and dark, a lot of the wildlife heads out for extended foraging trips across the Southern Ocean. A few hardy souls remain through the winter months however, keeping us company and keeping the rangers and Albatross and Giant Petrel Program staff busy monitoring what they do throughout the darker months.
Three species are brave enough to bring up their chicks during the sub–Antarctic winter: king penguins, grey petrels and wandering albatross — so these species are the main focus of our winter fieldwork.
Grey petrels are burrow–nesting seabirds, raising their chicks in burrows underground. While first reported breeding on Macquarie Island was in 1900, cats and rabbits had a detrimental effect on their numbers and breeding was not observed again for almost 100 years, until 1999. With cats and rabbits now successfully eradicated, grey petrel numbers are starting to rise, with over 120 breeding pairs found last season.
Grey petrel burrows tend to occur in clusters and known breeding sites are distributed around much of the island’s coastal slopes with the greatest concentration found on North Head, just north of the station. Over the past few months we have been trying to determine their breeding population size by searching for and checking burrows. This can be very cold work! It is nearly always wet and windy and sometimes there is snow. Finding a burrow amongst the dense tussock can be a challenge, but after a while you get an eye for the tell-tail signs like diggings, faeces and a distinct, musky smell.
Finding the burrow is just the first challenge; the next is to determine what is in it. This is usually a multi–step process. A torch is used first to peep inside. If nothing can be seen then a pocket camera is used at arms length to look in further. If this still does not reveal anything a GoPro on a stick is used to look even deeper. There is quite an art to keeping your fingers warm enough for them to work, but not so thickly swaddled in gloves that you cannot operate a camera anymore! It is always a great reward when you pull your muddy arm back out of a burrow, look at the photos you have taken and see a beautiful fluffy chick!
King penguins are present on Macca year round. With a 14–month breeding cycle adults breed on average twice every three years. Chicks are present almost year round, with new eggs hatching as the chicks of other pairs are fledging. This unique breeding cycle means it is important to obtain good counts of chick numbers over two or three consecutive years to obtain a true estimate of the population size. Almost every August since 1976 an island-wide chick count has been made. The most practical way to do this is to climb up high on the escarpment and take photos of the chicks from above. This is followed by a painstaking process of counting all of the chicks in the photos, which is quite a slow and difficult task given there can be well over 70,000 chicks, and they all look the same!
Our other winter residents include blue petrels, sometimes to be heard around dusk calling from their tiny burrows, and gentoo penguins that keep busy by making practice nests in preparation for their spring breeding season. Juvenile elephant seals also haul out on the beaches for a time, and giant petrels continue to fly about, as do kelp gulls and Antarctic terns. Fur seals still make an appearance on the beaches, and this winter we have even had some special visits from leopard seals and sea lions.
With winter now nearing its end, more animals will start to return. Within a few months the now relatively empty beaches with fill up with mating elephant seals, royal and rockhopper penguins will be making a racket in their colonies, and the cries of light-mantled sooty albatross will again be heard from the slopes.
Being on the island as it changes through the seasons, watching the different species come and go, young hatching or being born and then growing up until they too are ready to go their own way is incredible to see and something I am lucky to be able to experience.
Penny Pascoe, Macquarie Island Wildlife Ranger