Welcome to the forum.. What kind of wildlife? a 70-200 is generally too short for small birds and stuff.. Most canon shooters I know have at least a 100-400 F4.5-5.6 USM or the 400 F5.6 but they are both a little over 1K used...
For a starter, canon's 70-300 is pretty OK. I shoot Nikon so I have not tried many other Canon lenses. But if you can save up for the 100-400, you won't regret it.
What kind of wildlife?
I like African Wildlife and often you can't get quite close which is why I am saving up to replace my own Nikon 80-400 F4.5-5.6G