"Predators, including birds, rodents, shrews, ants, and spiders, play a role in some areas in reducing the numbers of free-living ticks."
http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/72120.htm
I'm guessing lizards, frogs, toads, and small snakes are also potential tick predators. So developing good habitat for the greatest number of critters will help keep the tick population down.