posted by rfvv .
1. The lizard is walking on a branch.
2. The lizard is running on a branch.
3. The lizard is creeping on a branch.
4. The parrot is singing.
5. The parrot is chirping.
6. The parrot is twittering.
(Can we use all the expressions?)
The grammar in all sentences is fine, but I wouldn't use chirping or twittering with the parrot sentences. Singing is fine, but I'd also use talking.