Why do crossbills and eagles have different beak shapes?

The shape of the bird’s beak is determined by what it feeds on. This was discovered by Charles Darwin in his research. The different shape of the beak is a manifestation of modification variability. The eagle is a bird of prey that eats meat. In order for the eagle to conveniently tear off pieces of flesh, its beak has a sharp hook. The bunch feeds on hard nuts and in order for him to crack them easily, the bunch has a massive and powerful beak, which helps him to quickly snap the dense nut shell.