On 15th October the penguin arrival count started. That is, from 15th October we trek out to Bechervaise Island, sit and count the number of Adélie penguins that are present on the island. We continue to count them every second day through to 10 November when we then count them every day.
Initially there are very few penguins. In fact, for the first few counts there were no penguins at all but slowly the numbers increased. From zero to seven to 28 then the numbers jumped to 128 and have continued to climb reaching 960 on October 27th. Numbers are at their highest at the time of peak arrival which is mid-November when we can expect as many as 5000 Adélie penguins.
We continue the count through to 21 November when the arrivals start to level off.
So how do we count them?
Each observer is provided with maps and photographs of penguin sub-colonies, a field book and pencil, a counter and a set of instructions.
Upon arrival the nesting penguins settle into 18 recognised sub-colonies each of which have been photographed, labelled and referenced for our purposes (referenced A through to R). We use the maps of penguin sub-colonies along with photos to navigate to and delineate each sub-colony. We count each penguin in that sub-colony, record it in our notebook and then move on to the next sub-colony.
These sub-colonies are usually discrete with large separation from other sub-colonies, but some sub-colonies are separated from neighbouring sub-colonies by only a small distance and therefore are not so obvious to the person doing the counting.
Two observers undertake the counts each time. They count the total number of penguins within each mapped sub-colony on the island and not confer with each other about their counts until all sub-colony counts on the island are complete. Each observer uses a counter, just as door-person would at a nightclub, and from a vantage point where they have a full view of all of the sub-colonies (which also minimises the need to move around the island and thus minimising disturbance) they click away.
To assist in the counts for when the sub-colonies grow too large the observers use natural features such as rocks and nests or other land features to help break down the large sub-colonies into smaller units to facilitate more accurate counting. It also helps to cast an eye over the sub-colony first and pre-plan how you intend to manage the count before you start. As once you start the count you can’t stop until you have counted every penguin in that sub-colony.
Each observer records their count for each sub-colony in a separate notebook. When all counts on the island have been completed, the two observers compare their overall totals. If the total island counts differ by 10% or less, then the count is complete. If the total island counts differ by more than 10%, identify which sub-colony contributed most to the difference, return to that sub-colony and repeat the sub-colony counts (for example, if one sub-colony had counts of 210 and 260, and another sub-colony has counts of 21 and 26, then the former sub-colony would be recounted because it has the largest absolute difference). If the total island counts now differ by less than or equal to 10%, the count is complete; if not, the sub-colony with the largest absolute difference is again recounted (this might now be a different sub-colony than the previously recounted one), and the process is repeated until the total island counts differ by less than or equal to 10%.
During the arrival count period the penguins are courting and are sensitive to disturbance, so we must keep our movements and voices as slow and low as possible. We never get any closer than what is necessary to facilitate the count.
How do we record and process the data?
As previously mentioned each observer records their count in a separate notebook. These notebooks are labelled ‘Beche arrival counts 2014’. Each count is recorded on a separate page for that particular day where we write the date and the observers name at the top of the page. We also record the letter of the sub-colony ie. A or B etc.
Once the count is complete and both observers have conferred and returned to station, the data is transferred across to an excel spreadsheet.
What do we do with the data?
For our part, nothing. That is we simply wait for the field biologists to arrive on the first voyage of the season who use the data for scientific research.
What exactly does that mean?
Here at Mawson we assist in facilitating many scientific programs with each science program contributing to the Australian Antarctic Division and the Federal Government’s overall scientific direction.
The Adélie penguin counts at Bechervaise Island feed into three such programs. I have listed the public summaries for each of these programs below. Each program is assigned a research number ie. 4086 etc.
Detecting potential fishery and climate change related impacts through the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR) Ecosystem Monitoring Program. CCAMLR manages the harvest of Antarctic marine living resources so it is sustainable to both harvested and dependent species. The CCAMLR Ecosystem Monitoring Program is one means of achieving this objective. Continuing Australia’s CCAMLR Ecosystem Monitoring Program will serve as a baseline for detecting impacts from a future krill fishery in east Antarctica, provide a tangible indication of Australia’s commitment to sustainable fisheries, extend and add value to the most comprehensive, long term predator monitoring program in the Australian Antarctic Territory, and contribute to the assessment of non-fisheries impacts such as climate change.
Seabird response to environmental variation and change: identifying drivers of key ecological processes. Identifying potential threats from a changing environment on Antarctic seabird populations requires understanding key ecological processes and their driving factors. This project focuses on determining driving factors for seabird demography, phenology, breeding site distribution and foraging habitat. Seabird data will be linked to spatio-temporally coincident data of biological and physical characteristics of the ecosystem to develop explanatory models and, where possible, predictive models to explore the outcomes of plausible scenarios of future environmental change on seabird populations.
Monitoring the status and trends of Antarctic seabirds to improve fisheries. Seabirds are useful indicators of fisheries and climate change impacts in the Southern Ocean. This project aims to develop and apply cost-effective monitoring approaches to determine population status and trends of a suite of seabirds across the Australian Antarctic Territory. Region-wide population estimates will be used to determine seabird prey requirements at spatial scales relevant to fisheries management. The methods and data will contribute to ecosystem-based management of fisheries, assessing climate change impacts, and identifying conservation needs of, and threats to, Antarctic seabirds.
Steve Robertson, Station Leader