Landscape-scale experiment demonstrates that Wadden Sea intertidal flats are used to capacity by molluscivore migrant shorebirds.

摘要: Summary 1. Whether intertidal areas are used to capacity by shorebirds can best be answered large-scale manipulation of foraging areas. The recent overexploitation benthic resources in the western Dutch Wadden Sea offers such an ‘experimental’ setting. 2. We review effects declining food abundances on red knot Calidris canutus islandica numbers, based a yearly mapping effort, long-term colour-ringing and regular bird-counts from 1996 2005. focus three-way relationships between suitable area, spatial predictability survival. 3. For each sampling position, intake rate (mg AFDM s )1 ) was predicted multiple prey species functional response model, digestive maximization (this model explained diet earlier studies knots). This enabled us derive distribution which 10 years analysed with measure autocorrelation, i.e. Moran’s I. 4. Over years, when accounting for threshold value meet energetic demands, knots lost 55% their area. ran parallel decrease numbers 42%. Although there also patchiness (i.e. less information about location feeding sites), this did not yet lead additional loss birds. 5. To cope these landscape-scale declines stocks, increase instantaneous processing would required. we show that indeed enlarged muscular gizzards, gizzard size enough compensate decreased 6. Survival Sea, colour-ring resightings, declined 89% first half our study period 82% second could account almost decline numbers; rest must have moved elsewhere winter. 7. Densities per unit area remained constant at ha 2005, suggests been using full capacity.