2 sentences

1. 雌雄配合后，便会开始筑巢。

   cí xióng pèi​hé hòu, biàn huì kāi​shǐ zhù​cháo.

   After mating, the pair will begin to build a nest.

   Source: Dong Chinese Dictionary

2. 燕子衔泥筑巢。

   yàn​zi xián ní zhù​cháo.

   Swallows carry mud in their beaks to build nests.

   Source: Dong Chinese Dictionary