Turn Your Flash Into a Super Tele
Add this fact to the shortcomings of on-camera flash, and it's no wonder that added light is underused by many amateur wildlife photographers.
Walt Anderson's Better Beamer flash extender is a Fresnel lens that mounts on a shoe mount strobe to refocus the light into a tighter pattern. Field tests and sample flash patterns are here.
Luminous Landscape has a review of the Better Beamer. While most of the info deals with on-camera flash, the better possibilities are in conjunction with off-camera strobe.
A Fresnel is different from a snoot. While a snoot merely restricts the beam of light (wasting some of it) the Fresnel concentrates much of the light into that tight beam. This gives you the ability to reach out forther with a telephoto lens, or to throw more light into a restricted beam shot outside to better overpower the sun.
This Strobist group discussion is full of information on shooting wildlife with strobes, including some common-sense cautions. There is also this excellent tip from Kin Lau to ensure that the over-zoomed flash is pointed exactly at the subject. He remotely triggers a flash which is mounted on someone else's camera, someone who's tracking the same subject.
Wildlife photographer Frans Lanting uses small flashes - including ones with similar Fresnels - extensively in his location work. There is a good interview on his general technique here.
By Mike H.