Ardea
Official journal of the Netherlands Ornithologists' Union

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Scheiffarth G. (2001) The diet of Bar-tailed Godwits Limosa lapponica in the Wadden Sea: Combining visual observations and faeces analyses. ARDEA 89 (3): 481-494
Estimating diet composition of Bar-tailed Godwits Limosa lapponica by visual observations was hampered by large amounts of unidentified prey items. Therefore, additional analyses of faeces were conducted. Overall, 17 prey species were found in the droppings, but only four polychaetes, the Lugworm Arenicola marina, the Estuary Ragworm Nereis diversicolor, the Catworm Nephtys hombergii, Scoloplos armiger and one crustacean, the Shore Crab Carcinus maenas were taken regularly by the birds. In faecal samples the number of polychaete chaetae, hooks, jaws and bivalve umbos were estimated, which allowed in the case of Nereis diversicolor, Nephtys hombergii, Scoloplos armiger and the Baltic Tellin Macoma balthica an estimation of the minimum number of prey individuals per dropping. The ratios of these prey species to each other in the faeces were used to correct for the unidentified prey taken during observations. The diet of Bar-tailed Godwits showed a seasonal pattern, as well as differences between males and females. Diet was similar between the sexes in winter with Nereis diversicolor, Nephtys hombergii, and Scoloplos armiger comprising 99% of the prey items taken. In spring 20% of the prey items of males were Macoma balthica, whereas females took the Sand Mason Lanice conchilega instead. In late summer Arenicola marina was an important prey for females but its importance decreased with decreasing prey availability in autumn. Towards winter the proportion of small polychaete species like Scoloplos armiger and Nereis diversicolor increased in the diet


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