Island of the terns: a public secret
19 Jul, 2008, 14:15 (GMT -04:00) Amigoe English
By Raul Henriquez http://www.amigoe.com/artman/publish/artikel_44711.php
ORANJESTAD – Aruba was already known to have its own rattle snake species and a small owl deviating a tiny bit in appearance from its kin in other countries. But amongst the 175 estimated bird species on the island, another unique situation has surfaced amongst the family of the terns.
Of this bird which is locally referred to as bubi chikito or meuchi , there are only ten different kinds which choose Aruba as their nesting ground. From the black and brown noddy to the Cayenne tern. Adrian del Nevo who has been researching the presence of the terns on Aruba says “ As far as I know, there’s no other place in the world where so many different terns choose the same place to lay their eggs.”
Strangely enough the birds have chosen five ‘unattractive’ riff islands in front of the oil refinery Valero to nestle. The closest to the bay of Rodgers Beach consists mainly of cobbles, coral and rocks. For the bridled tern it’s the ideal environment to lay eggs, but the rare Cayenne tern doesn’t want anything to do with it. Only ‘Island 3’ is popular for this breed for its sandy structure.
“The Cayenne is quite a rare bird”, explains Del Nevo during his last expedition to the islands this year as the breeding season of all kinds is almost over. Together with volunteers, he’s measured, weighed and counted thousands of eggs and tern chicks in the last months. “20 percent of the world population of the Cayenne appears here. It should actually be named the Aruba tern, for there is hardly any research done in French Guinea’s capital ‘Cayenne’.”
In the last year it has been going well again with the population eventhough the effects of hurricane Ivan drastically changed the composition of the riff islands in 2004. Big chunks of land were wiped away and lost to the sea. Also parts were covered with stones and debris, useful for the Bril tern, but disastrous for the Cayenne-tern. On Island-3 sandy parts remained, but the future isn’t exactly rosy. Dune plants keep on growing on the riff, which is also of no use to the Cayenne, but is to brown Noddy. This tern lays its eggs under bushes and between plants. Because all the island are more and more being grown over, their kind has strongly increased.
With each visit, Del Nevo pulls out some of the green to uphold the population of the ‘Cayenne’. “You ask yourself if there should be human interference.” The scientist usually gets stuck on this question, for he doesn’t say much about it. While in the US he’s considered the appointed expert in the area of ecological issues. He’s already written dozens of environmental reports there. On Aruba however he plays the biological field worker who studies the living environment of the birds, and especially that of the terns. Perhaps it has to do with the fact that since he started his research, Del Nevo is being financed by the oil refinery situated across from the tern islands. In 1999 the Coastal at that time asked him to go to Aruba to find out what effect the refinery had on the flora and fauna. Del Nevo then discovered an enormous tern population. “I noticed that they especially needed their rest at night, and that noise and light have to be taken into consideration. This was also the case for the terns nestling on the small riff islands in front of Oranjestad. For instance fireworks were lighted on Queens day which scared off the birds. The day falls right on their nestling time.”
Without the oil industry nothing would have come from a program for the unique tern population, says Del Nevo. “Everyone hates these companies, but let it be a positive aspect.” Since Coastal started it, every owner of the oil refinery in San Nicolas has adopted the tern program. El Paso followed and no Valero is the sponsor. In the meantime Valero’s personnel feel so sorry for the birds of the ‘bird guy’ that they have given themselves up as volunteer to clean the islands and sound the alarm if they encounter ‘strange birds’ on the island. That could be illegal immigrants or drug smugglers. They usually alarm the police and the coast guard about it. Their frequent presence is a repellant and so aids the piece and quite for the birds. On some of the islands there are signs with an English text saying that the terns are protected by law, and that it is forbidden to disturb then during the months of April and August or collect eggs. Del Nevo: “But still people unfortunately go there thinking it to be a good barbeque spot. It would be ideal if the government would appoint this area as an official marine park. But now we are even waiting for permission to place extra warning signs. We already received the money to product them from Valero, but the government apparently wants to take the time to decide for itself what should be written on the boards.”
Naturally Del Nevo believes that ‘his birds’ could use better supervision. “Effectually it’s up to Aruba, but we also have to manage the nature and its birds.” One of his interventions was forcing back the rats which ate the eggs of the terns. Together with volunteers he also places nestling boxes for the Bril tern for example, who it is true loves rocky surfaces, provided there’re suitable nestling places. The boxes enlarges that result.
For the government there isn’t a direct financial advantage, knows Del Nevo, and as to the interest there’s a possibility. In order not to disturb the animals, it can also not be a tourism destination for nature amateurs. According to him the terns are a public secret which should or should not be exposed. “But you could install binoculars at Coco Beach and place web-cams on the island and show them in the hotel”, suggests Del Nevo.
When Del Nevo talks about the terns and their riff islands, it’s becomes apparent that the birds are good indicators for the natural environmental situation of Aruba. “They fish a good 40,50 miles from here, often to the north of Aruba, where they feed on surface fish, like flying fish or squids. You soon notice if something is wrong with the fish population.” The food program of the Cayenne tern is very accurately fixed. Every adult picks up one fish for their young at a relatively short distance. That fish should be between eight and ten centimeters. If that fish is a bit smaller, then the young will have insufficient food, but if it is bigger, then the chance is big that the food will fall out of their beaks, or that a greedy sea-gull will take it from them. Del Nevo can also read from the large amount of eggs if there is something wrong with the tern population. “But sometimes you don’t really know whether the tern’s situation is only influenced by the Aruban environment, as we still don’t really know where they go to after the breeding season. Transmitters are too heavy for these birds and too small for satellites. But we suspect them to go to Brazil, since a hunter there had sent us the number of the ring around the leg. If the new owner of the refinery will be Petrobras, then we’ll be alright. Brazil is also a country where the terns go to when they can’t lay eggs anymore. Terns going on pension; that would be unique in the bird world.”