Sooty tern conservation - Scarecrow bio-acoustic systems play a part in sooty tern conservation


Courtesy of Scarecrow

Scarecrow Bio-Acoustic Systems, a leading international innovator in bird dispersal technology has been instrumental in helping the Sooty Tern recolonise one of its former nesting sites, bringing the seabird back to Denis Island in the Seychelles, after an absence of over one hundred years. Until recently, Uckfield based Scarecrow Bio-Acoustic Systems Ltd has been renowned for developing leading edge technology to disperse birds by playing their distress call but now the company is using its pioneering methods to attract this tropical seabird by playing its nesting call.

The Sooty Tern breeds on islands throughout the equatorial zone. There are about 750,000 pairs of Sooty Terns nesting on Bird Island in the Seychelles. However, just 40km away at Denis Island it's a completely different story.

Following human settlement, Denis Island became densely forested and, because Sooty Terns nest in open spaces, the birds were lost. One hundred years later, the new owners of the island would like to see their return and are attempting to attract the seabirds back to nest.

To do this they enlisted the help of Chris Feare, an ornithologist at WildWings Bird Management, and have sacrificed two hectares of forest close to the southern coast of the 140 hectare island. This has created an open space where the ground cover plants favoured by Sooty Terns have been encouraged to grow. In late May 2008, the beginning of their nesting season on nearby islands, plots were marked out in the open area. In some, plastic models, painted to emphasise the signalling patterns of the Sooty Tern plumage, were positioned.

Scarecrow Bio-Acoustic Systems' One-Shot product was used to help attract the seabirds by playing the sounds made by a large nesting colony of Sooty Terns. Four loudspeakers were placed in some of the plots and were controlled by Scarecrow's One-Shot playing bird calls at a natural sound level of over 100 decibels during the day, and switching to a lower intensity as happens in large colonies at night.

This is the first time Scarecrow's technology has been used to attract birds rather than disperse them and it has worked beautifully. Throughout June and July, two Reading University students monitored the plots and recorded any Sooty Tern activity. They discovered that passing Sooty Terns were attracted to the open area, flying down to investigate and circling low overhead. During that time, over thirty landings were recorded.

Significantly, most of the landings were in plots that contained both models and loudspeakers. This suggests that, used in combination, models and broadcasts of Sooty Terns colony calls can be attractive to visiting birds.

Chris Feare, WildWings Bird Management comments: 'What we have learned this year paves the way for further trials in 2009, when we will use a modified system of presenting the models and calls, and add two speakers broadcasting out to sea. This should help us to persuade more birds to land, with the hope of some of them laying eggs.'

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