You'll propably only need a tripod for nightshots.
Even at dawn / dusk, at shutterspeeds around 1/20 at FULL zoom, you'll find the IS makes for 99 out of 100 images perfectly sharp / still, unless you have VERY shaky hands
I even have a picture of a roe-deer, taken under dark clouds, during RAIN! around dusk (about 10 minutes before FULL-dark), shutterspeed: 1/2 Sec! Handheld
makes a fine 8"x10" on my wall
You'll never ever ever ever regret getting a C2100 for wildlife!
I've been so happy with it (even though I own more camera's), that I've been condidering getting a back-up C2100 extra should my current one ever die.
Anyhow, enjoy!!!!!!!! You'll be amazed at the zoom + low-shutterspeeed-handheld combination
the I.S. is what 'makes' this cam to my eye