Resumen de Stopover use by the Eurasian Spoonbill Platalea leucorodia of wetlands on the Basque coast (northern Iberia)

Juan Arizaga Martínez, Rafael Garaita Gutiérrez, Héctor González, Maite Laso

• The Eurasian Spoonbill is a species of conservation concern in Europe and thus a priority species from a management and conservation standpoint. Its North Sea population migrates along the Atlantic seaboard of Europe to its wintering areas in south-western Iberia and Mauritania.

  Spoonbills stop to rest and refuel in a number of wetlands situated along the northern Iberian coast. Detailed knowledge is still required for a better understanding of how these birds use these wetland areas. Our aim here was to explore and compare the use of the Basque coastal marshes (Txingudi and Urdaibai) by Spoonbills during the autumn migration. We used data collected with a single survey protocol during autumn migration in 2012 and 2013 at three sites: the Orueta Lagoon and the Lower Marsh at Urdaibai, and Txingudi. Overall, the only – and obvious difference – between Urdaibai (i.e. pooled data for Orueta and the Lower Marsh) and Txingudi was that Urdaibai hosted more Spoonbills. Within Urdaibai, however, the actual site hosting the greatest number of Spoonbills varied annually. Foraging rates were found to be higher at Orueta in 2012, although the causes of this difference are unknown. The proportion of Spoonbills foraging, sleeping/preening or flying at each site only varied in relation to the tide at the tidal site (Urdaibai-Lower Marsh, where proportionally more Spoonbills foraged, and fewer birds were sleeping/preening at low tide). The stopover duration was less than one day for >90% of birds and did not differ between sites. More research is still needed to understand why Txingudi was less used by Spoonbills than Urdaibai. Also of particular interest is the identification of the causes that may explain variations in foraging rates.