The effect of postural adjustment on the thermal environment of greater snow goose goslings

This study examines how changing from a standing to a sitting posture influ ences the thermal environment of greater snow goose goslings (Chen caerules cens atlantica). This was investigated by estimating the standard operative temperature of four heated taxidermic mounts (3, 10, 20, and 30 d old) exp osed to various wind velocities (0-5 m/s) and ground (16-23degreesC) and ai r (0-15degreesC) temperatures, in three orientations (head, flank, or tail toward the wind) and two postures (sitting and standing). Changes in postur e influenced both conductive and convective heat exchanges. At low wind spe eds, sitting on the sand reduced the standard operative temperature of gosl ings, while at high wind speeds sitting enhanced this temperature index. We calculated that a net thermal gain would be obtained by sitting on cold sa nd at air temperatures of 5, 10,and 15degreesC when the wind speed exceeded 3 m/s for most orientations toward the incoming wind. However, this critic al wind speed would be 23% lower following a 7degreesC increase in ground t emperature. Our study suggests that postural changes can have important con sequences on goslings' thermal environment.It also stresses the importance of considering the synergistic impact of conductive and convective heat tra nsfer processes, when studying the impact of postural changes on thermal en vironments.