Got up a little late, just before the sun came up, so I did a round to the south end of the motu before my cold Nescafe. Same cast of characters hanging out. The great frigates were already mostly overhead but the two females I saw perched the day before had not moved. About 15 fairy terns mobbed me, the masked boobies were cruising the beach to check me out, flying over repeatedly, the red-footed boobies didn’t care and the petrels were doing their dive-bomb routine. All quiet on Ducie.
Petrel Census Day
We had a big assignment today, to census all the petrels in the forest and try to figure out what species they are. We broke up into two teams: myself and Andrew, and Heather went her own way. We decided to do transects across the motu from lagoon side to ocean side every 200 meters and record all birds to within three meters of our path. We would take a waypoint for every sighting and take a photo. That way we could put them on the web and let others discuss what we found. We synchronized our GPS, watch, and camera and began. Andrew and I walked down to the far end of the motu to the killing fields where all the petrels have washed up on the beach and the cabbage trees are just skeletons.
It is kind of like Christmas when you do your first transect in a new place: you don’t know what you are going to find. On the first we had a good number of petrels. The first discovery was that we were not only dealing with adults and kids—some adults were on eggs. Then the second discovery was that there seemed to be pairs in many cases. The third discovery was that we had no idea what species we were dealing with despite having two bird books and all the publications on Ducie birds. The babies with down are slate black. Those ready to fledge already have some white or not. The final discovery was that there were a lot of dead birds in the woods too, not just on the beach—actually more dead birds than we were seeing live.
The second transect seemed pretty tragic. The cabbage trees were almost 100% dead and the ground was covered with Boerhavia, the herbal ground cover that hadn’t shown up in any of the previous floral surveys of the island. The petrels we found were usually hiding under the dead trunk of a tree, very exposed to the sun’s rays. We came across a chick that was ready to fledge and its underwings were matted with the little glutinous fruits of the herb. There is no way that bird could fly. He looked completely helpless and every time he moved he just picked up more fruits. I felt like I was looking at someone drowning in quick sand to a certain death. Maybe this explained the dead birds?
Who Are These Fine-Feathered Friends of Ours?
Our attempts to identify the species were pointing to Herald petrels. The couples seem to have two colors, one darker than the other. Luckily we decided to take pictures of every single bird on the lines. While my emails indicated otherwise, it felt like maybe we were at the tail end of the breeding season, at least for what I thought was the Herald petrel. That would explain what seemed like the remnant juveniles, older puff-down chicks and some still on eggs. The dead birds indicated that the population had been there a while. That would track if the Herald breeds before the Murphy’s. We found a dead red-tailed tropicbird juvenile on this transect as well.
We took a swim after the first set of two transects. The sunburnt backs of my legs were hurting. I felt a little feverish and every time one of those dead cabbage branches stabbed me it felt like a bee sting on the back of my legs. I was walking as daintily as possible but the vegetation was damn thick… so the cool water of the lagoon was sweet. From the view through the clear water there looked to be very little coral life in the lagoon and few fish compared to Millennium Island which we had visited on an earlier Pristine Seas Expedition. We saw no sharks but big blue and pink parrot fish and butterfly fish.
As the transects proceeded south the number of petrels went down, the live cabbage forest canopy went up and the Boerhavia herb went to zero. We met Heather in the middle. She had moderate success throughout, all the way from camp.
We finished the south-west part of the motu in the PM, same drill. There are not a lot of petrels on this end on the ground but many flying, making amazing vocalizations. There are also very few dead birds on that end. It seemed like a good idea to take pictures because I am sure someone versed in petrels will see important signs about species identification and health right away.
And the Grand Total Is…
So we may have done 18 transects, one every 200 meters with a width of 6 meters, so that means we covered three percent of the island. We saw no more than 200 birds in the transects which has a simple extrapolated count of 6600 birds total, which is probably an overestimate. This is a very far cry from what you’d expect in a place that is said to have maybe 300,000 birds at the peak season. So far there has been no sign of rats.
After a nice sunset, I built a little fire to have a cup of hot Nescafe. They ship’s crew is actually bringing food to the island for us, so we are eating like kings. Tomorrow we do more intensive ID and some trash clean up.