Bird Island Diary — February 2009
February is high summer on Bird Island. Although the days have started to get shorter, for the last two years February has brought some fine, settled days, perfect for exploring the island at a time when the work isn’t so intense. After the disruptions of ship calls towards the end of December, this month again saw no ship visits and everyone on Bird Island settled into an enjoyable working routine.
In terms of the seal fieldwork, this tends to be a less busy period than the chaos of December when the fur seal pupping is in full swing, but come the start of February, the pups that were born on the Special Study Beach (SSB) are ready to get their flipper tags. At two months old, they are no longer the quiet, docile and sleepy wee things they were at birth, but have grown into fat, angry little seals, all snapping teeth and growls of rage when you try to pick them up. This makes tagging excellent sport for the brave, although it can be a painful experience if you don’t get it right, and the pup manages to get its teeth into arms, legs or fingers!
Despite a very productive seal pupping season, with 782 pups born at SSB, there has also been a high proportion of these pups dying. We have seen several indications that feeding conditions for the predators at sea have been poorer than in other years — namely the almost-total failure of the gentoo penguin breeding season, large individual krill in fur seal diet samples, longer-than-usual foraging trips by female fur seals (between bouts of feeding their pups) and high mortality of fur seal pups.
This has made tagging our target of 300 pups quite a challenge this year, and by the end of the month, ably assisted by our visiting scientists from the National Institute of Polar Research in Japan, I had managed to tag 280 pups. It is likely that over 300 of this season’s SSB pups had died before we got around to tagging them, as a consequence of the poor at-sea foraging conditions.
It will still be two months before the pups leave Bird Island to brave the Southern Ocean for the first time, and many of them have yet to moult out of their black pup fur into their sleek swimming coat.
As well as working on the fur seals, the Japanese team of Akinori, Kentaro and Takashi were deploying small devices on several of our feathered residents. These included time-depth recorders, GPS position loggers and even some tiny cameras that captured an image every minute for a real ‘birds-eye view’. They spent many long days in the field, waiting for both black-browed albatrosses and macaroni penguins to return to their nests to give Aki and his team the opportunity to retrieve the devices and download the data.
Their work on fur seals included attaching small data recorders to the lower jaw, which showed individual feeding events with ultra-fine detail — showing when a seal opened its mouth each time it ate a krill or fish! Of course, working at close proximity to the sharp end of a seal involves a lot of care, and the fact that no one was bitten during the course of this procedure is testament to the world-class and professional nature in which field science on Bird Island is carried out.
Derren’s work during this month involved looking at diet samples from the mollymawk (black-browed and grey-headed albatross) chicks. The chicks are rapidly gaining weight at this point, as both parents return every few days to feed them. Grey-headed albatross diet consists mainly of squid, whereas their black browed cousins eat more krill.
The wandering albatross adults continue to incubate their eggs, the earliest of which hatched at the end of the month. These tiny balls of white down often take more than 24 hours to fully emerge from their egg, and grow rapidly with their rich oily diet that their parents feed them. All fingers and toes are crossed that this year is a successful one for the wanderer chicks, and that there are many healthy chicks around at fledging time in November and December.
Meanwhile the non-breeding birds continue to dance on the grassy meadows around the island. Wandering albatrosses take several years to build up a bond with another bird before they breed, and may return for many consecutive years to display to a prospective mate. During the summer, you can see many groups of displaying birds at various places around the island.
The penguin team had a busy month. On February 1st, they carried out the gentoo penguin chick census — to see how many chicks have made it through to the time when they fledge. Unfortunately, the same poor foraging conditions that led to the high rate of fur seal pup mortality has had a devastating effect on the gentoos this year. From an initial 4000 nests back in November, only 40 chicks made it through the season to the point where they were ready to go to sea for the first time. When compared with last year, where on average one chick fledged from each nest counted, this is put into perspective. Such is the way of natural environmental variation from year to year…
The macaroni penguins have fared better, and on 19th February Fabrice and Stacey supervised the weighing of 130 chicks at the Fairy Point colony (Little Mac). The chicks are also given a passive integrated transponder (PIT) tag, similar to an identity microchip that you can give your pet dog, which gives each macaroni penguin chick a unique number, like a barcode. This is read and recorded by a computer as the chicks pass in and out of the colony, and this provides a record of the penguin departing and returning to the colony without the need for constant human observation. In the future, it is hoped that this will be complemented by an automatic weighbridge that Fabrice and Stacey have been trialling this year: recording an accurate weight of each penguin as it crosses in and out of the colony.
As the fieldwork is a little less intense for most folk, February allows many opportunities to get out and see more of the island. On February 27th, Fabrice, Takashi, Dickie and I took the opportunity to bivi out in Wanderer Valley. Although only 15 minutes above base, it felt like another world on such a calm and peaceful night. A mattress of spongy Acaena and moss made it a comfortable nights sleep for everyone.
We celebrated two birthdays this month: both Kentaro and Akinori had Bird Island birthdays. Bird Islanders like birthdays, because along with film nights (twice-weekly), Saturday dinners and many other occasions, they are a great excuse to make cake! So prolific has the cake-baking been this year that butter stocks are dangerously low, and we are unsure as to whether we can make it through to the ship call/butter resupply in mid-April at this rate of cake consumption! On Aki’s birthday we also had a fantastic barbecue, courtesy of Dickie.
So as the summer rolls on, it is good to take the opportunity to get out and about when you can. One of the more enjoyable summer activities is to watch the sun setting from the top of Roché Peak — made all the more exciting when the cloud is low, but the summit is clear, allowing you a view over the top of the clouds. Before too long, the nights will be drawing in and the weather will turn more noticeably wintery. There is still summer fieldwork to be completed but the summer is short and winter approaches fast. However evenings like this remind you what a special place Bird Island is.
Best wishes to everyone at home.
Zoological Field Assistant