I never understood the evolutionary push to develop flight, because I thought of it as an expensive form of transport.
Until this graph, which shows the cost of transport to actually favor flight over terrestrial locomotion.
Until this graph, which shows the cost of transport to actually favor flight over terrestrial locomotion.
So the trend is towards more efficiency per kilogram for heavier animals, presumably due to square-cube law[0]. Or maybe the 3/4 scaling law[1][2].
[0] https://en.wikipedia.org/wiki/Square%E2%80%93cube_law
[1] http://mathbench.umd.edu/modules/misc_scaling/page20.htm
Basically the y axis is a measure of efficiency. The x axis just spreads out the points so you can compare things of similar mass.