Seabirds breed come heavy rains or strong winds

White tern aka fairy tern breed year round and are usually seen in pairs, they lay a single egg on a branch crevice

The Seabird survey on Cousin Island Special Reserve was typically carried out during the South East monsoon season – a period of low rainfall and heavy winds – but since 2013 this is now done in both the North West (NW) and the South East (SE) monsoon seasons to compare trends between these different times of the year. The NW season, running from November to March, is time for heavy rains but calmer winds and sea.

The White Terns breed all year round, although their numbers have been shown to be slightly higher between January and February. In 2017 the population numbers were quite close across both seasons and only fluctuating by a few breeding pairs. As has been seen over the years not a lot of White Terns chicks make it in the NW monsoon season.

“I worked with a group from our Conservation Boot Camp program and was intrigued by their reactions,” says Kara Beggs, Nature Seychelles Science coordinator based on Cousin Island. “All the participants I was working with were doing seabird monitoring for the first time. Charmain and Jim Yule were quite in shock with the high number of Noddy nests counted. But when we would get to plots of minimal to no nests, and they only counted say five nests they would look at me as if to say ‘did I not count properly?’ I simply explained that the number of nests is not necessarily the same for every plot.”

Wedge-tailed shearwater adults leave the nest before dawn and return at night. photo by Jovani Raffin

During the SE monsoon season Cousin Island saw quite a few days with heavy rainfall and stormy winds, many tree-nesting seabirds were heavily affected, more so the chicks that had not yet fledged. Lesser Noddy chicks were found in many areas around the forest floor having been blown out of their nest.

Many chicks that had fallen out of the nest from stormy weather patterns, would still manage to stay close to the nest location and reside in one spot on the forest floor where the parents could successfully feed and provide for their young. However, the Lesser Noddys are still the most prolific seabird on Cousin, with a strong, stable population of around 50,000 breeding pairs.

“At night the atmosphere in the forest changes, this is when the tropical shearwater and wedge-tailed shearwater are active. This is the ‘fun’ part for both staff and Conservation Boot Camp participants,” says Yan Coquet, the Conservation Boot Camp program coordinator. “The main challenge is to find the numbered poles in the dark. We rely on memory but sometimes this is tricky when they are not visible behind a tree or a rock pile. The Wedge-tailed shearwater has a creepy call much like a wolf howl or a human baby crying. I enjoy watching the puzzled looks of anyone hearing this for the first time.”

A pair of breeding whitetailed tropicbirds, they nest on the ground on Cousin Island which is predator free. photo by Jovani Raffin

The White-Tailed Tropicbirds increased in numbers from last years’ population census count during the SE monsoon season where there were 1,234 breeding pairs recorded compared to this year’s 1,671 breeding pairs recorded. Regular monitoring will contribute to long-term data on consistency with nesting seabirds on nearby islands, with an aim to see if the White-Tailed Tropic birds are faithful to their nesting islands and can contribute to juvenile success rates.

The future of Cousin Island’s research and monitoring of nesting seabirds is looking towards giving us a greater insight on these important birds.

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