Hi. Even it's a bit late, I will add I also do wildlife monitoring, and it (CHDK) is the great must-have we always dreamt about but never thought it would exist and...for free. Oh, what a wonderful word...
Ok, I will add you must try motion detection scripts, since you will only want to record presence of fauna. In case you monitor from dusk to dawn, just remove the IR blocking filter which protects the sensor (google it, a japanese guy has nice video) but replace it with a clear glass so as to avoid dust stacking because of static electricity (yo know, countryside, wildlife, wilderness...).
I use external power (external battery pack), and IR illumination for night imaging; a nice script should include focus at 1st shot, since at night it is already focused and save time, batt. and avoid error in focus.
Just feedback any result to see how it's going.