I am making a wild life game in which animals are expected to do the following.
They wander most of the time in the jungle with terrain.
The animals will attack the player on sight follow the player closely to kill, it will avoid obstacles, but will not climb large slopes.

My question is: with out a waypoint graph or navigation graph on the terrain, can i make it.
Eg.I can make use of this techniques: http://www.red3d.com/cwr/steer/

For 95% of the stuff your animals will want to do, I would say that you can probably just use steering behaviors. The only time that will look bad is if the animal needs to determine a path around an object to get to the player. If your world is relatively open, that won't happen much.

Thanks a lot.

If you want some examples of implementation, I've written a library using c++ style doing the same thing as opensteer, so either look into that or you can checkout my code (MIT License) at http://github.com/DropechoStudios/desteer .

Thanks, I will check it out.