Seasons change bird species on Holt Island
It is obvious that bird species recorded in any one spot change over the year: migrants come and go. With Holt Island inaccessible for much of the year, it has still been possible to chart patterns from the Waits. Every 4-5 days from the start of April until the end of June, dawn sightings and sounds were recorded in a standard 10-minute count. The count was resumed from late August to late September.
The spring/summer period produced 48 species, with most days recording 20-30. The autumn counts produced fewer (38), normally 20-25 on a given day. The two sets of lists differed: the autumn lost most warblers, but gained four new species such as red kites and grey wagtails. Overall, the two sets of lists were almost 30% different.
In spring, hearing birds was not hard: most were advertising at full pelt, and song thrush was especially obvious. By autumn, things were quieter- and the thrush was noticeably completely absent. Sight and contact calls became more important in late summer, and were the keys in autumn. Walking through Holt Island in late September confirmed that the impressions from the Waits were real: there were fewer birds of fewer species heard or seen.