The migration seasons of birds as recorded at Dungeness Bird Observatory in southeast England

This paper summarises the migration periods of birds at Dungeness Bird Observatory, Kent, southeast England, as calculated from daily counts conducted over an 18-year period. Mean spring migration dates for different species ranged between 6 February (Greenfinch Carduelis chloris) and 26 May (Reed Warbler Acrocephalus scirpaceus), and mean late summer/autumn dates between 11 August (Reed Warbler) and 27 November (Great Crested Grebe Podiceps cristatus). In general, species which arrived early in spring tended to depart late in autumn and vice versa. The overall average spring passage date for all species was 9 April and the overall autumn date 3 October. Long-distance migrants, wintering in sub-Saharan Africa, tended to arrive later and depart earlier, spending a shorter period in Britain than short-distance migrants wintering within Europe. Although the population levels of birds are higher in autumn than in spring, in some species the spring totals at Dungeness far exceeded their autumn totals. The annual cycles of the birds passing through Dungeness, as reflected in their migration dates, were centred not on the longest day, nor on the warmest, but roughly midway between the two.