Zavodovski Expedition. Team Penguin.
Scrambling up the cliff meant it was finally happening, I was finally landing on Zavodovski Island. Home to the world’s largest Chinstrap and Macaroni penguin colony, which has never been properly censused, getting onto this island had been a goal for many years. In addition, a volcanic eruption on the island had potentially killed many of the penguins in 2016, and so we were eager to finally get a proper count of the birds.
Chinstrap and Macaroni penguins near our landing site, with Vinson at anchor. Photo by John Dickens.
Counting over 600,000 pairs of nesting penguins would be impossible to do by hand, and so we planned to use drones to take photos of the colonies from above. However high winds were forecasted overnight and into the next day, so flying the drones was going to be impossible for the time being. Instead, John Dickens and I set-off to recover some small geolocator tags that had been deployed on the penguins a year ago by another Vinson team. These tags were attached around the ankle of the penguins and recorded where the penguins had been over the winter months, which is also completely unknown. Did they stay close to Zavo or disperse away? Would a winter krill fishery around the island impact them if they stayed? These geolocators should tell us, but finding them proved difficult.
Both the Macaronis and Chinstraps were incubating eggs, meaning their legs and feet were tucked up under them, hiding the tags from view. So, we spent the first evening carefully feeling the right ankle of each adult on its nest, hoping to feel a tag attached to a small band around the ankle. We checked twenty, thirty, forty birds with no luck, but then John beckoned me over. He had found one. He held the bird as I quickly snipped the band off and placed the tag into an inside pocket of my jacket. The data it held was hugely valuable.
Checking the birds in this way became a daily task as the adults swapped over incubating duties. Over the week that we were ashore, we only recovered four of the 35 tags that had been deployed the previous year. We were disappointed to find so few, but tracks from those four penguins would still help hugely in understanding where they went in winter and therefore whether a winter krill fishery near the island could impact them.
As the days ticked by, the winds were still too high to fly the drones, so our next task was to deploy satellite-linked tags on both the Chinstraps and Macaronis. These tags would send data back in near real-time while they were foraging at sea, showing us where they went to feed while incubated their eggs and after their chicks have hatched. This data will be more accurate than the geolocator tags and will reveal the areas that are most important to them during the breeding period.
Chinstrap penguin with a satellite tag greets its mate at the nest. Photo by John Dickens.
Chinstraps track
Macaroni track
But we don’t just need to know where they’re foraging, but also what they’re feeding on. So while we moved through the colony each day, we listened out for the tell-tale sound of a penguin pooing! It sounds almost comical, but is very helpful for finding fresh faecal samples, which we collected almost as soon as they hit the ground. I have since sent these samples back to my lab at the Cornell Lab of Ornithology, where I’ll sequence the DNA found in their faeces. This will tell us to what extent they rely on Antarctic krill as a food source, or whether they supplement their diet with fish and other invertebrates as well.
Gemma Clucas collecting faecal samples from Macaroni penguins. Photo by John Dickens.
Each evening on the island, Skip radioed the boat for a weather forecast, and we listened carefully to the wind speeds, hoping to fly our drones. The drones allow us to take images of the colonies from above, and then count the nests from the imagery at a later date. Three days after landing, we got the news we needed, the next day the winds looked light enough to fly! So John and I set our alarms for 4am so that we could make the most of the good conditions.
The next day dawned grey and gloomy (as usual for Zavodovski!), but the wind had finally dropped, so we headed out just after four with the drones and our backpacks full of spare batteries. We started at the southern end of the island near to camp, and flew transects back and forth above the colonies, taking overlapping photos that will then be stitched together to produce an orthomosaic covering the whole area. After a few hours, we had completely covered the southern end of the island, so we returned to camp for breakfast and to recharge the drone batteries with our small generator.
After coffee, porridge, and with another set of fully charged batteries in hand, we walked to the northern end of the island, where the densest penguin colonies are found. Soon after we arrived, the clouds lifted slightly, revealing the steaming flanks of the volcano covered with hundreds of thousands of nesting penguins, and the plume of volcanic gasses drifting away from the top of the volcano above us. It was breath-taking, but knowing how quickly the conditions could change on Zavo, John and I didn’t waste time. John immediately got to work flying the drone while I collected more faecal samples so that we could compare diets from the northern and southern breeding birds. Then, we deployed ten more satellite tags, to see whether the foraging ranges of the birds from the northern and southern parts of the island also differed. It was a long day, and we didn’t get back to camp until 8pm that evening, where we collapsed into the tents to be greeted by a delicious risotto made by Skip. But the 16-hour day was well worth it, as we had flown nearly the whole island, deployed the last of our tags, collected a full set of faecal samples, and sure enough, the next day the wind was whipping again!
Team Penguin:
Gemma Clucas, Cornell Lab of Ornithology.
John Dickens, British Antarctic Survey.
