Digging for Shearwaters

Sadly due to the severe winds and a high swell advisory predicted over the next week, the Wedge Island seabird study had to be cut short by a few days. We are after all around latitude 40 south, which is well known for its nautical name as the roaring 40’s; and how appropriate that name is. It was an awesome 3 days regardless; I got to handle shearwater chicks, camp on an amazing island under brilliant stars, and learn a lot about seabird ecology. Now I’m back at the Narrara Backpackers in Hobart, getting reading to embark on a 3-4 day walk around the Tasman Peninsula to kill time and hopefully not myself. The following is a summary of my notes while on Wedge Island.

February 28th, 2011

Caught a city bus to University of Tasmania’s (UTAS) main campus in Sandy Bay, a short 15 minute ride, where I wandered around for some time trying to find the Southern Elephant Seals where I was told we would all meet. Jaimie, the project leader and honors student at UTAS, has been on Wedge Island for a few weeks now, and we were to meet her upon arrival on the island. As usual I was an hour early, and as usual our ride out to the island was a half hour late. Eventually the two other volunteers, a couple from Germany who had been traveling around Tasmania for a couple of months, strolled in with mounted backpacks. Joss (pronounced Yoss) is an evolutionary biology student and Norrah a student of medicine, both in Germany. They decided to take a break half way through their studies to travel and gain some field experience, not a bad move. We chatted for a while until our boat driver Andy finally appeared. We loaded the gear, filled up 5 jugs of water, grabbed a box of needles and several bags of food, threw in an inflatable dingy, and headed down the road to the launch ramp.

Andy put the boat in the water and gave us the usual rundown on safety. As we started the twin outboard motors and began on taxi out of the harbor, Andy turned and announced,

“Now the engines have been giving a warning alarm lately, so we’re just going to hope they stay quiet today.”

We nodded in approval.

“BEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEP”

I chimed in, “They’re not being quiet”.

Andy gave a blank expression; I would have done the same. So we charged out of no wake zone and out into the open harbor. The water was glass calm, not a ripple in sight. With these conditions we’d be out to the island in less than 40 minutes. But after the engines died we drifted for a while and limped back to the launch ramp. We then sat around for an hour until Andy found another boat, this time a fiberglass hull instead of aluminum. So all in all it took about 3 hours to reach Wedge Island, and in that time the conditions went from beauford 0 to 3. It was a jumpy ride out, but a nice one. We passed massive flocks of shearwaters by the thousands, interspersed with an occasional Shy Albatross. The dark brown birds at times blanketed the rolling sea, and would lift off in unison as the bow parted the black sea. It was amazing no one was shit on, that was to come later.

Finally Wedge Island came into view, and from our angle it did indeed look like a giant rocky wedge covered in lush green vegetation contrasted with golden plumes of bunch grasses. The apex of the island had bushy pin- like gum trees and more traditional eucalyptus. The steep rocky pinnacles that lined the western slopes of Wedge were covered in a bright orange lichen, with a gradual slope ending in a cobble beach on the eastern side. Our camp and the nesting colony we studied are located on the eastern slope. There are no sandy beachs on the island, so shuffling gear and people from the cobble shoreline to the transfer boat was tricky. We had to row the now deflated overloaded dingy back and forth, getting everything wet in the process. Field work is never easy. Luckily the swell was not big, and all the gear and precious volunteers made it on and off the island without a hitch.

After lunch we settled into camp, pitched our tents, and got ready for our first venture up into the colony. Our tents were situated at the base of the colony, so the walk to the burrows was only a few hundred meters. According to Jaime, if I remember correctly, around 20,000 breeding pairs of Short-tailed Shearwaters have a burrow on Wedge. I may be wrong on the exact figure, but it’s in the tens of thousands. The island is also a breeding site for Little Penguins. Both the shearwaters and penguins arrive on the island at dusk, and leave the following dawn. So we heard a lot of birds, but hardly ever saw them.

The plan was this; during the day we would walk around the colony and conduct morphometric measurements (measurements of various growth rates) of a select number of chicks. This involved locating the correct burrow number and shoving your hand down a arm’s length hole until your face is resting on the ground, and grouping around until you felt the chick, or in some unfortunate and surprising cases an angry adult that decided not to leave the burrow like the rest. Or even worse a penguin…luckily we didn’t encounter any; they apparently get very angry when disturbed. Fortunately there are no snakes on Wedge, so there were no poisonous fangs waiting at the end of the rabbit hole; only potential scorpions, ants, flees, ticks, angry penguins, and the gentle nibble of curious and slightly pissed off chicks.

Once we got a good handle on the puff balls, we slowly pulled them out to weight them, measure their bill length, depth, and head length. After the leg bands were read off to insure the correct chick, the chirping ball of lent was gently settled back into place at the end of the burrow. This was repeated for around 30 burrows, and took about 2 hours. We also noted any dead birds scattered around the colony, and checked for plastic in their gut; plastic of course being the number one killer of seabirds today.

Nightfall was when the real show began. Like clockwork, approximately 20 minutes after sunset, the first shearwater would arrive over the island, and was quickly joined by hundreds more. It’s a real treat to see these ocean roaming birds awkwardly flapping over land. They appear graceful at sea, with outstretched wings like little stealth gliders; but when trying to land on solid ground, they have to constantly beat their wings to slow down, as they circle the island to locate their burrows. Dusk was also when the penguins began to emerge from the waves, and march along the very tracks we used to navigate the bunch grass. Often we had to wait for the penguins to waddle off the trails so we could pass.

Around 30 minutes after they arrive, the shearwaters located their burrows and begin to feed their chicks. As the activity in the sky decrease the noise from the burrows amps up. Bird colonies are notoriously noisy, as the parents call to their chicks, the chicks respond, and the rest just seem to feel like expressing themselves. Jaime tells us that it often seems as though the shearwaters compete with the penguins for most vocal seabird of the year.

Our task at night was to capture birds containing data loggers. These are small computer chips and battery, with light and temperature sensors incased in resin. They record the duration of daylight the bird experiences, and the water temperate while they rest on the sea. The amount of daylight recorded can be used to determine the bird’s position on earth, biased on a known starting date and location, and complex mathematical equations. This information will help shed light (as it were), on where these birds go to gather food for their chicks, how long it takes, and the implications this may have on commercial fishing and environmental regulations. The loggers have a battery life of 5 years, but have to be removed from the bird’s leg in order to extract the data. So it was important to check the burrows of birds with loggers each night after they return to feed their chicks. Unfortunately they sometimes can be 20 days at sea on foraging bouts before they “fly home”, so we only encountered one bird with a logger, but it was still very interesting to learn about the technology and its implications. The loggers are about the size of your thumb nail; science has come a long way.

At the end of the night, we retreated back to camp and huddled around a fire under the spectacular array of stars, roasting marshmallows (which was a real treat for the Germans, who have never tried such a thing). I’m currently listening to the rain patterning on my tend, masking the sounds of the plump chicks in their cozy burrows with their noisy parents vomiting up tasty bits of krill and fish oil, while Little Penguins stand around molting and making themselves heard in the bushes. Surrounded by seabirds and a few great people, on a small southern ocean island at the southern tip of Tasmania.