What deer have going for them is the ability to blend in to a herd so that when chasing a deer, if it gets in with the herd, you may end up chasing a freshly rested deer instead of the one that you’ve worn out which gets a chance to rest and regroup. Christopher McDougall’s Born to Run has some interesting chapters about this (http://www.amazon.com/exec/obidos/ASIN/0307279189/donhosek)