In a recent paper, Dawson et al. (1999) investigated how the morphology of the contour and downy afterfeathers of gentoo penguins Pygoscelis papua function as thermal insulators. Their model considered how the morphology of individual feather barbs interact to create an efficient insulatory barrier. They noted that, during diving, the feathers must be compressed and return to their original configuration due to stored strain energy. In addition, the downy feathers of penguins have to withstand significant wind loading whilst the birds are on land (Taylor, 1986). Despite the obvious necessity for mechanical competence and resilience of down feathers, we still know little about their mechanical performance.