Is the sony fe 600mm f 4 gm oss long enough for birds?

Here is what the site says about that.

From Sony FE 600mm f/4 GM OSS: Sony FE 600mm f/4 GM OSS: A prime lens by Sony for Full frame cameras, 600mm f/4. Specs - Maker: Sony - Focal length: 600mm (prime) - Maximum aperture: f/4 - Made for: Full frame sensors - Mounts: Sony E - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 600mm. - On APS-C (Sony E): like 900mm on full frame; f/4 gives about the depth of field ...

From Sony FE 200-600mm f/5.6-6.3 G OSS: Sony FE 200-600mm f/5.6-6.3 G OSS: A zoom lens by Sony for Full frame cameras, 200-600mm f/5.6-6.3. The usual bird lens on Sony: long, internally zooming, and fair value.

Quoted from this site's pages.