This week at Mawson: 17 January 2020
The skuas at Bechervaise Island.
The skuas at Bechervaise Island
Skuas have a reputation for being fierce and aggressive, ‘the scavengers of the south’. They feed on carrion, as well as fish and krill, and are often seen predating on penguin eggs and chicks - not penguins! Many people don’t like them too much, perhaps because they’ve fallen for the endearing penguins! We (Kim Kliska and I) are also quite fond of penguins, but we have a deep respect for skuas. Here’s why.
The skuas that are here at Béchervaise Island are south polar skuas – one of the seven species of skua. They are amazing fliers! Yes they swoop down on to unsuspecting penguins to try and nab an egg or chick (to feed their chicks), but they also fend off other skuas from their territory (where they nest and feed) and are incredibly agile – flying and landing with amazing precision. Sometimes we hear a skua chasing another skua through the air – it sounds like a small jet plane has just flown overhead! The speed and maneuverability is quite amazing – exceeding 72km per hour in pursuit flights (according to research by Alerstam et al. 1993 - https://royalsocietypublishing.org/doi/abs/10.1098/rstb.1993.0048).
They are also extremely diligent parents. They have to be - they are vulnerable to dangers too! The male and female work together to incubate their eggs and raise one or two chicks. The pair often call and pose to each other (head bows, spread wings), and have quite a vocal repertoire – sometimes a low murmur (like a talking kind of tone, to their partner or chick), sometimes a laughing kind of call (not like a kookaburra, more like a ‘ha ha haaa’ sort of laugh), and other times a high pitch screech (like they’re yelling – probably making sure other skuas get the message to rack off!).
This year we are attaching tracking devices to the skuas at Mawson to identify their summer and winter movements. To do this, we need to locate birds on a nest, so we know they are tied to a location, which we can go back to in order to recapture them and recover the device. Then we capture a bird, attach the device, release them, and off they go. We recapture them after a few days (for summer movements) or after one year (for winter movements). We use different devices for different movement data. We also record how many eggs they lay and how many chicks are successfully raised (to calculate breeding success – a good indicator of food availability throughout the season).
Working this closely with the skuas means we get to know them quite well, especially because we are working with known individuals and observing them frequently through time. Many people (biologists and wildlife enthusiasts) who observe animals this closely will tell you that from these observations it often becomes apparent that individuals have unique characteristics, or personalities – some skuas appear to be much more aggressive than others, some seem to push the territorial boundaries more than others, some are much more diligent to their nest and chicks than others. I think when you start to appreciate this diversity of behaviour in skuas, then you start to look beyond the penguin-eating and open your eyes to the world of a very impressive predatory bird.
The skuas on Béchervaise Island are certainly the dominant predator in the area, but we do occasional see southern giant petrels (SGP) too (a small number breed not too far from here). The ‘SGPs’ are quite impressive – not only do they look like something out of Jurassic Park, they also sound how you’d imagine a Pterodactyl to call. If you want to learn more about SGPs and or one of the other skua species (the brown skua), head over the Macquarie Island station updates page – they also have quite a few stories to tell about the birds they have there!
- Marcus Salton (AAD Vertebrate Biologist)
A Mawson Summer So Far...
Hi, my name is Simon White and I’d like to share a few of my experiences of the past summer season while at Mawson station in Antarctica.
As with all expeditioners, I began my current season in the city of Hobart, Tasmania. Each season, those selected to take part in the upcoming Winter Expeditions and the Summer support programs are provided accommodation and varying levels of training relevant to their positions of employment. With my employment as Station Supply Officer for Mawson, I was seconded to the Australian Antarctic Division’s warehouse in Kingston, which is the beginning of the supply chain for a majority of materials and equipment headed to Macquarie Island and the three stations on the Antarctic continent.
The stations in Antarctica are accessed from Hobart either by flying to Wilkins ice runway or by sea on board Australia’s ice breaker, the Aurora Australis, soon to be replaced by the RSV Nuyina. The resupply voyages for each station are a vital part of station support, bringing fresh food and water and fuel as well as a fresh compliment of wintering expeditioners to maintain the infrastructure and scientific research carried out in Antarctica year-round. Summering expeditioners like myself provide the extra support during the short summer and favourable weather conditions that allow us access to this fantastic place.
This season was a bit different for me as I was to be at Davis Station prior to the Aurora Australis arriving on her first resupply voyage for the summer. I was there to assist a fellow Station Supply Officer, Chloe W, with final preparations before the ship arrived. Because of the short time frame, Chloe and I flew to Wilkins on a commercial style A319, before transferring to a smaller aircraft known as a Basler BT-67, a remanufactured and modified version of the Douglas DC3. It was a great way to see the coastline from Casey station all the way through to Davis. By the time we landed on the sea ice near Davis we had been travelling for well over 12 hours from Hobart, not counting the extra hours waiting for the weather to clear before we departed for Wilkins.
The few days we lost waiting to depart for Antarctica didn’t affect our preparations for the first resupply of the season. The extra time at Davis contributed to a smooth resupply and maintained the Aurora’s tight schedule for the rest of the summer.
I didn’t see the completion of the resupply, as I, along with a smaller group of expeditioners who had travelled down by ship, were flown on to our ultimate destination at Mawson. The Basler was our mode of transport this time. It afforded the capability of carrying not just ourselves but some critical cargo for the station personnel which were coming out of their winter isolation. Most notably mail from home and some fresh fruit and vegetables.
The station was still thawing out from a fairly respectable blizzard count during the winter. There were great tails of “blizz” (built up snow) everywhere that a lee formed from the incessant wind coming down from that plateau behind the station. Part of my job early in the season was to help clear snow from some of the vital parts of infrastructure that required access. Due to the typography of Mawson, some places were bare rock while other areas were under metres of snow and ice.
Once the snow had been cleared or lessened in content, it was simply a matter of time to let the sun do its bit to melt out the remainder of the station. Then I could go back to my primary role of preparing the various types of cargo that are repatriated to Hobart each year, along with the previous wintering team and the lucky few summer expeditioners who get to see Mawson station in all its facets.
I would not have time to describe all the history of the station here. There are pieces and photos from the past decades of Australia’s involvement with Antarctica, as well as the original buildings still standing amongst the newer buildings, which gives the station a connection back to February 1954 when it was first established.
At present we are four to five weeks out from the arrival of the Aurora Australis on her last resupply voyage to Antarctica. Before long we will be in full swing and receiving the much-needed supplies of personnel, fuel, food, and materials and equipment to maintain the integrity of the station through another fast approaching winter period.
As mentioned, the last voyage on the Aurora Australis will be a special time for everyone on board to catch up on the past season at both Davis and Mawson as well as some welcome fresh food. The time it will take to sail back to Hobart will be too quick for some and not soon enough for others. It will mark the end of another chapter in the ANARE (Australian National Antarctic Research Expeditions). Before long, a new era of Australian expeditions to Antarctica will begin with the commissioning of the new ice breaker, RSV Nuyina. Many past and present expeditioners will be lining up to head south on her maiden voyage.
- Simon White (Mawson Summer Station Supply Officer)