First they dragged an anaesthetised penguin behind a spring balance to measure how much flipper power it would need to toboggan through the snow.Then they calculated how far its feet sank in soft snow so they could compare the energy expended while sliding with the effort needed to walk. The final question concerned the tradeoff between wear and tear on feathers and the benefits of tobogganing.The only way to do this was to kill the penguin and store it in the snow between periods of dragging its corpse behind the spring balance.First they dragged an anaesthetised penguin behind a spring balance to measure how much flipper power it would need to toboggan through the snow. Then they calculated how far its feet sank in soft snow so they could compare the energy expended while sliding with the effort needed to walk. The final question concerned the tradeoff between wear and tear on feathers and the benefits of tobogganing. The only way to do this was to kill the penguin and store it in the snow between periods of dragging its corpse behind the spring balance