Non-breeding waders in summer at a wetland on the east coast of Ireland

Abstract for CORC2017

Tom Cooney

The main objective of this work was to document the occurrence of fifteen non-breeding wader species at North Bull Island in Dublin Bay between spring and autumn. The presence or absence of each species was recorded during weekly visits from May to mid-July 2012 to 2015 and in 2017. Weekly counts were also carried out in 2017 to assess the size of their respective populations in summer. Species diversity was highest during the migration periods in May and late-June/July and lowest in mid-June. Within the ten week survey period, five species were present continuously, seven more were only absent occasionally or for short periods and the remaining three species occurred either sporadically or rarely. Although wader numbers in 2017 was lowest in mid-June, in excess of 450 birds were recorded during all June counts. The most numerous species in mid-June were Curlew Numenius arquata and Oystercatcher Haematopus ostralegus representing 80% to 90% of all birds present. Although weekly counts were only carried out in 2017, it is noteworthy that six species occurred in concentrations in excess of their respective thresholds for national importance. The results show that North Bull Island is an important site in summer for a diverse range of wader species some of which occur in large numbers. For many wader species there were no clear cut-off points between the departure of wintering birds, the spring movement of passage migrants and the arrival of summering bird. This has obvious implications for phenologists investigating potential changes in the duration of stay of ‘winter visitors’.
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