Is the canon ef 300mm f 4l is usm good for wildlife?

Here is what the site says about that.

From Canon EF 300mm f/4L IS USM: Canon EF 300mm f/4L IS USM: A prime lens by Canon for Full frame cameras, 300mm f/4. Specs - Maker: Canon - Focal length: 300mm (prime) - Maximum aperture: f/4 - Made for: Full frame sensors - Mounts: Canon EF - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Canon EF): as marked, 300mm. - On APS-C (Canon) (Canon EF): like 480mm on full frame; f/4 gives about the depth of ...

From Canon EF 200-400mm f/4L IS USM Extender 1.4x: Canon EF 200-400mm f/4L IS USM Extender 1.4x: A zoom lens by Canon for Full frame cameras, 200-400mm f/4. A professional wildlife zoom with a built-in 1.4x teleconverter.

Quoted from this site's pages.