Elephants don't climb hills

At least, not willingly, says this article, citing a short study by Jake Wall et al. in Current Biology.

But the researchers calculate that the energy required to climb a hill could be a main factor. Climbing uphill for 100 yards would require a half-hour of foraging to replace the energy used.

References:

Wall J, Douglas-Hamilton I, Vollrath F. 2006. Elephants avoid costly mountaineering. Curr Biol 16:R527-R529. DOI link