Prey selection by the Snail Kite (Rostrhamus sociabilis) in permanent and temporary wetlands of central Argentina

MAPELLI, FERNANDO JAVIER; KITTLEIN, MARCELO JAVIER

ORNITOLOGIA NEOTROPICAL

NEOTROPICAL ORNITHOLOGICAL SOC

Año: 2011 vol. 22 p. 281 - 293

1075-4377

Prey selection by snail kites (Rostrhamus sociabilis) on freshwater apple snails (Pomacea canaliculata) was studied in permanent and temporary wetlands in Buenos Aires province, Central Argentina. Live individuals of P. canaliculata and prey remains of this species left under perches by snail kites were collected in five temporary and three permanent wetlands. Frequency distributions of size of live and preyed-upon snails were compared at each sampling locality. Although snail kites selected prey by size both in temporary and permanent wetlands, the pattern of prey selection differed between wetland types. Snail kites selected prey of intermediate size in permanent wetlands but in temporary wetlands they selected for intermediate and large-sized snails. In spite of this selection pattern, snail preyed by snail kites in temporary wetlands was on average 8–17 mm smaller than in permanent wetlands. Estimates of snail abundance (and presumably prey availability) were higher in temporary wetlands than in permanent wetlands. Differences in habitat physiognomy and in snail abundance between both types of habitat could be responsible for differences in the pattern of prey selection between wetland types.