Foraging behaviour and diets of red-necked stints and curlew sandpipers insouth-eastern Australia

Diet and feeding behaviour of red-necked stints (Calidris ruficollis) and c urlew sandpipers (Calidris ferruginea) feeding in mixed flocks during the n on-breeding season were investigated in Western Port in Victoria, south-eas tern Australia. Surface pecking was the most common feeding action of both species, followed by jabbing for red-necked stints and probing for curlew s andpipers. Mean depths of substrate penetration were 3.4 mm (red-necked sti nts) and 14.0 mm (curlew sandpipers). The preferred feeding zone for red-ne cked stints was wet mud (86%) and for curlew sandpipers was shallow water ( 40%). Feeding rate did not vary between species but did vary between months and a ge classes for curlew sandpipers. Gastropods made up 68% of the sample volu me for stints and two unidentified species in the families Hydrococcidae an d Fossaridae occurred most frequently in terms of occurrence in the guts an d total prey items. Curlew sandpipers took a wider variety of taxa (12) tha n did red-necked stints (8), with polychaete worms (Nereidae) being their m ost frequently recorded prey and comprising 63% of the volume of the gut sa mples. When prey taxa overlapped in the diets of the two species, some size differences of prey were apparent. Differences in bill morphology and feed ing behaviour, including microhabitat use, corresponded with these differen ces in diets.