The Status of Breeding Common Scoter in Ireland, 2020

Abstract

The Common Scoter (Melanitta nigra) is a small black sea duck that is present in thousands around the coast of Ireland in winter, with a small population breeding on Ireland’s inland lakes. In 2020, a survey was undertaken to provide an updated estimate of the Common Scoter breeding population and to assess their productivity. Pre-breeding surveys revealed a potential breeding population of 50 pairs on four lakes. Lough Corrib held the greatest number of Common Scoter with 38 pairs. Seven pairs were recorded at Lough Ree, four pairs at Lough Arrow and one pair at Loughs Conn and Cullin. Lough Gara was also surveyed but no Common Scoter were found. Although the Common Scoter breeding population in 2020 was 38% below the 1999 population of 80 pairs, it has increased by 28% since 2012, when the population stood at 39 pairs. At three of the sites - Lough Ree, Lough Arrow, and Loughs Conn and Cullin - the breeding population has remained low but stable since 2012. The recent increase in the national population is due to a 36% increase at Lough Corrib from 28 pairs in 2012 to 38 pairs in 2020. Brood surveys were completed on all lakes which held Common Scoter in the pre-breeding surveys. Successful breeding was recorded on only two lakes, with a total of thirteen broods recorded: eight broods on Lough Corrib and five on Lough Ree. On Lough Ree, seven pairs produced five broods (71% breeding success) whereas on Lough Corrib 38 pairs produced only eight broods (21% breeding success). No broods were found on Lough Arrow or on Loughs Conn and Cullin. Productivity - the number of ducklings produced per breeding pair - was 1.1 on Lough Ree and 0.55 on Lough Corrib. To conserve the Irish breeding Common Scoter population a greater understanding of the population’s ecological requirements and associated pressures and threats is required. Factors contributing to population trends are not well understood, with populations at some sites showing stable or increasing trends while others have shown significant declines or extirpations. These factors have contributed to the population’s apparent dependence on Loughs Corrib and Ree. Empirical evidence from breeding sites is required in order to design, target and implement robust conservation measures that will allow the species to maintain or recover its populations and range. This report includes a number of recommendations based on the findings of this survey. This IWM was edited by Domhnall Finch. The NPWS Project Officer for this report was: Dr Sean Kelly.