Significant record of wedge-tailed shearwaters on Desroches Island
14.12.2009
In 2000 a group of researchers recorded a small colony of wedge-tailed shearwaters around the Desroches lighthouse.
Unfortunately this colony does not exist anymore, which could have been the cause of cats and rats present on the island.
Fortunately a second colony was later discovered in November 2008 at the opposite end of the island, around Muraille Bon Dieu, and is still successfully active.
Wedge-tailed shearwater, better known as ‘fouke dezil’ is the only large all-dark shearwater likely to be seen in Seychelles waters. Its large size and dark underparts separate it from the much smaller Audubon’s shearwater.
Adults emit an eerie wailing ‘woooh’ at their breeding sites and juveniles give various squeals. Birds are often far out to sea during the day, but stream past headlands in the late afternoon to gather in floating rafts off the breeding islands.
They visit their burrows at night. A single egg is laid in a burrow between September-October, at the end of the southeast monsoon, with juveniles fledging between February-March.
The Island Conservation Society (ICS) established a centre on Desroches in June 2009 with the aim “to promote the conservation and restoration of island ecosystems, sustainable development of islands, and awareness of islands their vulnerability and vital importance to the planet’s biodiversity”. One of the many activities on the ICS programme is the monitoring of the wedge-tailed shearwaters colony. Since the centre opened we have ridden down ever Monday evening at around 7pm to observe the colony and the bird’s behaviour. We also set rat traps to help give the birds the best chance of survival.
After about a month of looking we decided to choose 15 freshly dug burrows randomly over the area to get a better idea of what is happening. At times only 5 or 6 burrows could be seen with one bird; others empty or contain hermit crabs. We did not let this discourage us as these magnificent sea birds make their burrows curve at different angles which can make it difficult to get a good look at what is inside. On the last day of October, after a long day of doing beach profiling, we went to do the normal weekly check up and came away very excited because we saw eggs in the burrows for the first time.
This is remarkably significant because an island like Desroches which supports large numbers of cats and rats has got a very active breeding colony of wedge-tailed shearwaters. This makes Desroches unique from other islands such as Alphonse, which also supports these pests. The colony on Alphonse, which was found two years ago by the ICS team based there, has never been seen to lay eggs, and adult birds have even been found dead around the colony, presumably killed by cats. Today no birds are now found on Alphonse.
We, on the other hand, are still keeping our fingers crossed that in a couple of months hatching will take place and lots of babies will be seen, which will be a massive success for the team and for the population of these birds here on Desroches.
The Island Conservation Society promotes the conservation and restoration of island ecosystems.
by Danielle Jupiter