Learn French: C'est avec son bec que le cygne attrape les poissons. - It is with its beak that the swan catches fish.

In this cleft sentence structure, we use que because the subject of the action is already present in the second half of the sentence. The swan (le cygne) is the one doing the catching. We only use qui when emphasizing the subject of the sentence, like in C'est le cygne qui attrape les poissons (It is the swan that catches the fish).

Could I just say Le cygne attrape les poissons avec son bec?

Yes, that is the standard, neutral way to state the fact. Using the C'est ... que structure highlights the prepositional phrase avec son bec, emphasizing that it uses its beak specifically, rather than its feet or wings, to catch the fish.

Why is it son bec? Does the masculine son mean the swan is male?

No, son is used because the word for beak (le bec) is masculine. In French, possessive adjectives (like son, sa, ses) always agree in gender and number with the item being possessed, not the owner. Therefore, son bec translates to 'its beak' here, regardless of the swan's gender.

Why does the French sentence use les poissons when the English translation just says 'fish'?