Quantifying the importance for waterbirds of an urban rocky coastal site in Lanzarote, Canary Islands

We present the results of monthly censuses of waterbirds in a rocky coastal sector of the city of Arrecife, Lanzarote (Canary Islands). Spatial and temporal changes both in species abundance and composition were studied during two annual cycles. An aggregate total of 8,927 individuals were counted, representing 7 families, 14 genera and 24 species. The most diverse family was Scolopacidae (11 species), and the most abundant was Laridae. All species recorded in this study are considered to be regular migrants through the Canary Islands, except the vagrant Ring-billed Gull Larus delawarensis. Three species also breed regularly in the archipelago: Yellow-legged Gull Larus michahellis, Lesser Black-backed Gull L. fuscus and Kentish Plover Charadrius alexandrinus. Most waterbirds were found at the end of the summer, in winter or in late spring. For some species, spatial differences in occurrence were also observed between the different sectors of the study area. An average of 577 ±176 individuals, belonging to 18 species, spent the winter at this site; this represents 24.9% of the total Canarian wintering population of Ringed Plover Charadrius hiaticula, 21.7% of Grey Plover Pluvialis squatarola, 13.0% of Whimbrel Numenius phaeopus and 12.5% of Bar-tailed Godwit Limosa lapponica. More than 1% of the Spanish wintering population of Ringed Plover and Whimbrel can be found in this area. Due to its proximity to the city, there is high human pressure, so several management measures should be implemented to guarantee the conservation of the ornithological value of this site.