Population trends of seven land bird species from Aldabra were evaluated and showed that six of these species were increasing in abundance – the Comoros Blue Pigeon, Madagascar Turtle-dove, Madagascar Bulbul, Aldabra Fody, Souimanga Sunbird, and the Madagascar White-eye.

The seventh species, the Aldabra Drongo, remained stable over this time period.

This result was published in an SIF (Seychelles Islands Foundation)-authored paper  in peer-reviewed journal Bird Conservation International on the status of Aldabra’s land birds.

The paper used data from SIF’s long-term land bird monitoring programme from 2002-2013 where monthly surveys were conducted at seven locations around the atoll.

The increase in abundance ranged from 83-100% in the 11-year period, which may indicate that at the start of the surveys in 2002 the land birds were recovering from a disturbance still to be identified.

Some of the species seemed to be affected by climate; for example in years with more rainfall the abundance of the Souimanga Sunbird increased.

Other species showed seasonal behavioural changes, e.g. Aldabra Fodies became more vocal during breeding seasons, which meant that they were more obvious to the observers and more likely to be counted during the monitoring session.

An important outcome of these findings is that revisions to the long-term land bird monitoring programme are required. One of the suggestions is to record additional information on the ease of detection of different species during the monitoring session, as this can have an impact on the accuracy of the data recorded.

This ‘detectability index’ will be developed further by SIF, with trials of the new methodology expected next year.

SIF

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