RED-WING BLACKBIRD REPRODUCTIVE-BEHAVIOR AND THE PALATABILITY, FLIGHTPERFORMANCE, AND MORPHOLOGY OF TEMPERATE PIERID BUTTERFLIES (COLIAS, PIERIS, AND PONTIA)

In presentation experiments to red-wing blackbirds in eastern Washingt on, palatability of pierid butterflies varied over the birds' breeding season. The cloudless sulphur Colias eurytheme/ philodice was always more palatable than the cabbage white Pieris rapae and the western whi te Pontia occidentalis. Pontia and Pieris had similar palatabilities w hen demand for resources by the nestlings was relatively low. When dem and fcr resources increased at the height of the birds' breeding seaso n, the palatabilities of all three species increased, Moreover, Pontia was eaten more frequently than Pie-is, although the difference was no t significant. Differences in palatability among species were associat ed with differences in capturability in artificial predation experimen ts. Colias flew for greater durations and distances than the other spe cies prior to capture. The three species did not differ in flight spee d. However, Colias was missed more often; suggesting that the species differed in manoeuverability. Two indicators of flight performance in tropical butterflies, flight muscle ratio (thoracic mass/body mass) an d the position of centre of body mass, ordered with capturability of t hese temperature species as predicted. (C) 1998 The Linnean Society of London.