Tag Archives: wedge tailed shearwater

The secret lives of shearwaters

This post was contributed by Michelle Kappes and Kevin Coustaut, Laboratoire d’Ecologie Marine at the Université de la Réunion.

Shearwaters, like most seabirds, spend most of their lives at sea.  In order to learn about where shearwaters go when they are away from their breeding colonies, Dr. Matthieu Le Corre from the Université de la Réunion has begun a research program to deploy miniaturized electronic tags on wedge-tailed shearwaters (Puffinus pacificus) at sites throughout the western Indian Ocean.  These tags, or geolocators, collect data on light level that can be used to determine the position of the bird at sea.  Basically, the time of local noon is used to determine longitude, and latitude is estimated by local day length.  The tags are attached to a metal ring on the bird’s tarsus using a plastic zip-tie (see photo).  The tags also have a salt-water switch, and due to their placement, we can determine when the shearwaters are in flight and when they are resting or foraging on the sea surface.  By taking advantage of this technology, we can begin to get a picture of how these wide-ranging seabirds behave during their foraging trips to sea.

Wedge-tailed-shearwater with geolocator

Wedge-tailed shearwater with geolocator © Michelle Kappes

Also using geolocators, recent work by Catry et al. (2009) demonstrated that 9 wedge-tailed shearwaters breeding on Aride Island remained close to the colony when raising chicks, and later dispersed up to 3,500 km to the central Indian Ocean Basin during the non-breeding period.  Last year, members of Dr. Le Corre’s research team recovered 6 geolocators from wedge-tailed shearwaters deployed at Cousin Island.  Preliminary analysis suggests that shearwaters from Cousin Island disperse further east during the non-breeding period than those from Aride Island.  However, a larger sample size will be necessary to confirm colony-specific differences in foraging behavior.

During 14-29 September 2009, we deployed 24 geolocators on wedge-tailed shearwaters breeding within St Joseph Atoll, Amirantes group, and 24 geolocators on shearwaters breeding at Cousin Island.  Field work is planned to deploy similar numbers of geolocators at sites on Réunion Island, as well as off Mauritius and Madagascar.  This will be the first attempt to simultaneously study the at-sea behavior of this seabird species across a broad range of breeding sites.

Ultimately, these data will help us answer questions such as: do wedge-tailed shearwaters breeding at different sites in the western Indian Ocean travel to similar locations at sea?  Are there specific ocean habitats that are of particular importance for this species?  Areas of the ocean that are important to shearwaters may be important for other marine species as well, so these data could be used to help identify marine Important Bird Areas and possibly oceanic Marine Protected Areas.

shearwater in burrow

Shearwater in burrow on Cousin Island © Conor Jameson

However, as the geolocators store these data on-board, we won’t be able to answer these questions until we recover the tags at the end of the breeding season.  This may prove trickier than it sounds because once shearwater chicks reach about a week in age, adults only return to the colonies for brief periods to deliver meals to their chicks.  So we may have to wait until the next breeding season starts in 2010 to recover these tags and unlock the secrets of where these different populations of shearwaters spend their time at sea!

Bird rescue on Mahe

This week we had the privilege of the brief company of two seabirds at our office – a wedge-tailed Shearwater, Fouke in Creole, and Wilson’s storm petrel. Both Birds had been found and rescued by members of the public.

Wilson’s storm petrel

The storm petrel before its release

The Wilson’s storm petrel was found by a fishing boat around Denis Island and was brought in to us on the afternoon of Friday 23 by Captain J P Grancourt. Upon identifying the tiny bird as Wilson’s storm petrel,  we sent out an email to the bird committee to ask for advice on its feeding and release. It had no apparent injury and seemed to be just stressed, so it was put in a box to rest. It was fed, although with some difficulty as its beak is very tiny. Petrels feed on tiny shrimps, small squids, very small fish and planktonic crustaceans. We heard back from Adrian Skerret of the Bird Committee who advised its immediate release because of the difficulties in feeding. He also said that very few records exist in Seychelles of Wilson’s storm petrel; it has only once been photographed in Seychelles. On Saturday morning the bird was released on Mahe.

Wedge-tailed-shearwater

The shearwater brought to our office. Inset: shearwater nesting on Cousin

The shearwater was found at Pointe Larue near the agro-processing plant. Wedge tailed shearwaters are found on rat free islands in the Seychelles such as Cousin, Cousine, and Aride where they burrow on the ground to nest. Adults leave their burrows before dawn to fly out to feeding grounds at sea  and return in the cover of darkness. They are rarely found on Mahe. The Shearwater was confused but otherwise healthy with no injuries. It is being fed and will be released in a coastal area later today.

Wedge tailed shearwaters are also known as the moaning bird because of the eerie calls they make. In the past the call was associated with ghosts. They are even said to have caused a warden on Cousin to leave the island in haste! Listen to it here and tell us what you think.