Seasonal energetics of opossums (Didelphis virginiana) in Ohio.

1. Female opossums acclimatized to each of the four seasons were not significantly different (P greater than 0.05) in oxygen consumption at a Ta of 0 degrees C; the overall average was 0.

Interaction between posture, color, and the radiative heat load in birds.

The effect of the angle of incidence on the radiative heat load was determined for light and dark plumage. As the angle of incidence to the solar radiation source increases the difference in heat transfer between light and dark plumage disappears. Thus, by postural adjustment, a dark bird may become thermally white with regard to the radiative heat load.