Newsletter April to June 2012
The dry months of March and April were a blessing to the guests. They had beautiful sunny days and wonderful sunsets to add to their holidays. We cannot say much for the island. The long spells of sunshine were not too kind to the vegetation. The grassy areas turned brown literally overnight with so much sun and lack of rain. Our small farm did no better either, we lost nearly everything including the lemon grass, pumpkin, aubergines and most of the vegetables. We had to stop raking in front of the lodge because of the dust.
The rains that fell during the end of April and through the month of May were a blessing to the land this time. Within a couple of weeks, the island had turned green again and the farm started producing.
The doldrums in April allowed us to go out for dolphin spotting. Each and every excursion was a mind blowing experience. The guests had the privilege to admire and appreciate these playful creatures, jumping, swimming alongside the boat.. Mantas and turtles were other lovely animals spotted as well.
The top attraction during the last three month has been the sooty terns. The arrived in huge flocks in March and their numbers have been climbing ever since. The sky above the north point of the island is now a common sight for their aerial ballet. The best time to enjoy this spectacular display is at sunset. In spite of the fact that there are thousands of them flying around, collisions are very rare.
To be more on the serious side, the sooties are now on the ground preparing their nesting area. The grass in the colony has been flattened to make way for their nests. According to our ornithologist friend Chris Feare, an expert on sooty terns confirms that their numbers are very high this year compared to the last breeding season. Read on, report from Chris below…
“Are fortunes changing for Sooty Terns?”
“The Sooty Tern is one of the most numerous seabirds in the world and the western Indian Ocean has been estimated to host around 6 million breeding pairs, of which over 3 million nest in Seychelles. I have been fortunate to have been able to study the Bird Island colony since 1972, thereby learning a huge amount about their habits. Some events over recent years give me cause for concern.
The year of my most intensive and detailed study, 1973, and the period between 1993 and 2005 seemed to be very good for Bird Island’s Sooty Terns. They normally arrived and began laying in late May-early June and, apart from just one or two years when they failed to rear young (e.g. in 1994 when August rains led to an almost complete breeding failure by killing the chicks), breeding success has generally been good. It was notable that birds from the colony, situated in the north of the island, streamed down the western beach every morning, past the hotel, to feed somewhere to the south of the island, possibly over the shallow waters of the Seychelles bank. In the evening huge numbers returned from that direction to relieve their mates during incubation, or later in the season to feed their growing chicks. In the early 2000s there was a trend towards earlier breeding and in 2004 laying started in late April, the earliest recorded.
In more recent years this pattern appears to have changed. In 2008 and 2010 laying did not begin until mid June (I was unable to visit the island in 2009), and 2011 was one of the latest years on record, with intensive laying not beginning until early July. In all of these years we have seen no morning and evening flypasts from the hotel; instead the birds appear to be feeding to the north of Bird Island, over deep water off the northern edge of the Seychelles bank. Now in 2012, on 17 June, I am still waiting, with frustration, for mass laying to begin, signalling another late year, and once again the twice daily flypast of the hotel is missing. In 2008 we recorded the number of days that adults incubated their eggs before being relieved by their mates. In 1973, when I last did this in what proved to be a good year for breeding success, 60 % of incubation shifts lasted 24 hours whereas in 2008 only 16% of incubation shifts were as short as this, most being between 3 and 6 days long.
In addition to the problems faced on their ‘home’ ground, in May 2011 Sri Lankan conservation organisations reported finding sick and dead Sooty Terns both on the coast and inland. The cause of death has still not been identified with certainty but one of the birds found bore a ring that I had put on in Seychelles in 1995. Interestingly, another ringed Sooty Tern found dead at the same time in Sri Lanka had been ringed by a Reunion research team on the island of Juan de Nova, in the Mozambique Channel between Madagascar and East Africa.
This suggests that the problem in Sri Lanka affected Sooty Terns from a wide area. This is also true of the late breeding in 2011, since in addition to Bird Island, other large colonies were also affected, including Aride in Seychelles, Desnoeufs in the Amirantes, and even colonies much further afield near Madagascar and Europa in the Mozambique Channel. We simply do not know whether the two events of late breeding in Seychelles and unusual mortality in Sri Lanka were related.
The reasons underlying these changes are not yet known. While unsustainable egg collecting in Seychelles could reduce populations, it is unlikely to be the cause of such widespread delays in the onset of nesting. The differences between the earlier years and 2008 onwards observed on Bird Island suggest that the Sooty Terns’ food supply has changed. Some studies show that aspects of climate change could lead to a reduction in the intensity of the Indian monsoon, which in turn could affect winds and currents across the Indian Ocean and the fish populations that live within it. Increasing atmospheric carbon dioxide is leading to acidification of surface waters. Ocean temperatures are increasing. We also know that there has been a massive increase in commercial fishing in the Indian Ocean over the last 20 or so years. Whether any of these, or all of them, are already affecting Sooty Terns, through their food supply or by other means, is moot. But if the recent changes in the birds’ behaviour become permanent, one of the best ornithological spectacles in the western Indian Ocean could be under threat.“
The tropic birds population is stable. Problems with the ants invading the nests and attacking the young chicks. To solve this problem, we created ‘treated’ buffer zones around their nesting habitats to prevent the ants from getting there.
Fregates: Still a lot of fregates around, mostly juveniles.
Boobies: Four juveniles red footed recorded so far. We have started a programme to attract the boobies to nest on the island as they did once upon a time. We have established artificial nesting habitats in two casuarinas trees in the hope of luring them back to the island. We’re keeping our fingers crossed.
Migrants: Much less in numbers as most of the adults have already made their migration north since three months ago. The juveniles that stayed behind are lesser sanplovers, turnstones, sanderlings, grey plovers, wimbrels and one squacco heron.
Green Turtles: A very low start of the season with only twelve nests recorded. A female tagged 4 years ago was back recently for the first time after being tagged. Robby is doing nightly patrols to make sure he catches all of them coming up to nest. One turtle tagged on Aldabra was found nesting here very recently.
From the Bird Island TeamJune 30, 2012 12:00 am