As the three-month research on Saba’s Tropicbirds came to an end, researcher Lara Mielke presented some of the results during a well-attended meeting for everyone who was involved and interested at the Eugenius Johnson Center last Thursday evening.
Since she started her research on Saba’s most iconic seabird in late November last year, Mielke has managed to retrieve the data from 23 GPS loggers that she had placed on the birds. The data showed that at times these birds fly more than 500km from Saba out at sea in one day to catch fish, mainly flying fish.
“With the GPS loggers, we can identify the foraging areas and compare the data with the foraging areas Hannah Madden has identified for the birds from St. Eustatius,” Mielke told the audience which was clearly captivated by her presentation. The loggers were placed on the tailfeathers of one of the adults on a nest with a small chick at one of the three main nesting locations on Saba, Old Booby Hill, Great Level, and Tent Bay.
Mielke also found that unfortunately, the chicks at Tent Bay do not survive. The young chicks are mostly eaten by feral cats, which pose the greatest threat for Tropicbirds on Saba. The wild cats predate on the chicks, which reduces the Tropicbird population on the island.
Tropicbirds seem to return to the same location to lay their one egg and raise their chick. An estimated 1,500 Red-billed Tropicbird breeding pairs nest on Saba, a popular location due to the ruggedness and remoteness of the rocky, steep hillsides.
There are an estimated 8,000 to 15,000 breeding pairs of the Red-billed Tropicbird in the world of which 13 to 25% breed on St. Eustatius and Saba. Tropicbirds spend most of their time at sea and only come to land to breed. Little is known about the foraging grounds, the foraging patterns and the ecology of the Red-billed Tropicbird, which makes it even more important to continue studying these birds, Mielke said. Madden and Mielke will now start analyzing the data.
In order to better identify and in the long-term monitor Tropicbirds on Saba, Mielke also banded the birds she encountered. In the months of January and February, she worked together with Michiel Boeken, who has been researching Tropicbirds on Saba before and has banded a huge number of birds during the past weeks.
While working on Saba, Mielke received support from many people who accompanied her on the hikes on the steep, rugged hillsides to inspect the nests, ring the birds and place loggers. She also did activities with children from afternoon clubs and with students from the Saba Comprehensive School (SCS) so they could learn more about this iconic species of Saba.