![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
ABSTRACT
Capsule: Northern Gannet Morus bassanus counts obtained from a coastal monitoring network in northern Spain were highly determined by wind conditions.
Aims: To determine how external factors including weather conditions affect seabird counts in a land-based seabird monitoring project (Red de observación de Aves y Mamíferos marinos, RAM project; Seabird & Marine Mammal Observation Network).
Methods: Seabird counts were obtained from four study capes situated in the southeastern part of the Bay of Biscay in northern Spain. Counts were conducted on a monthly-basis for a period of 3 hours starting at dawn on each sampling day. Data used here were compiled over a 10-year period (2006–15).
Results: Northern Gannet numbers were chiefly influenced by meteorological conditions at a local spatial scale. Northwesterly winds were found to positively influence gannet abundance, whereas high relative humidity caused a decrease in abundance. Moreover, gannets were more abundant during the non-breeding period as compared to breeding period.
Conclusion: We recommend considering the effect of the wind and relative humidity on land-based seabird counts in the Bay of Biscay when handling data from the RAM protocol in order to avoid biases and misinterpretation of data. Since seabirds approach the coast during harsh weather conditions, the RAM protocol should be improved in order to better account for the distance at which the birds are seen.
Acknowledgements
We are grateful to the volunteers and entities (Sociedad Ornitológica Lanius, Arkamurka, Itsas Enara Ornitologi Elkartea, SEO/BirdLife, GIAM) supporting bird counts at the study capes. We also thank the two RAM Spanish General Coordinators (Xulio Valeiras, Salvador García). Almudena Fontán provided useful comments on meteorological conditions in the Bay of Biscay. This study is a contribution to the CHALLENGES (CTM2013-47032-R) project. Two anonymous referees provided very valuable comments that helped us to improve an earlier version of this work.
