Use of dredge islands by a declining European shorebird, the Kentish Plover Charadrius alexandrinus

Colonization of newly created habitats is a challenge for waterbird populations in a changing world. Knowing which habitat characteristics are required by waterbird populations is a research challenge for rational management of the new ecosystems and their aquatic bird populations. Since 1989 intertidal dredge islands have been built in the lagoon of Venice using sediments coming from regular dredging of lagoon channels and inlets. Kentish Plover, a species declining in Europe, readily uses these new sites as soon as they become available. Between 2005 and 2007, 75 dredge islands were surveyed each year and the number of breeding pairs of Kentish Plover estimated. Each year about one-third of available dredge islands was used by Kentish Plover. Between 34 (in 2005) and 131 (in 2007) breeding pairs were found, and possible differences in vegetation and morphological characteristics between occupied and unoccupied sites were investigated. Only age, mean elevation above sea level and extension of bare ground were statistically different; Kentish Plover preferred younger sites, with higher elevation and with larger areas of bare ground. The largest groups of breeding pairs, up to thirty pairs, were found on islands which also supported colonies of Little Terns. In the study period dredged islands supported about 60 % of the total breeding population of the lagoon of Venice and 4–6 % of the estimated Italian population. Along coastal sites where human pressure on beaches is particularly heavy, man made habitats such as dredge islands may become a valuable alternative breeding site for this and other species of conservation concern. Management works aimed at promoting the occurrence of this species at selected dredge islands have been made in the lagoon of Venice.