The Suicide Squad (2021)
In the scene where the actress stands in an atrium surrounded by flying birds, production filmed the birds in the cage, and the actor separately. In post production they placed the actor in the cage of live birds. Birds had been kept in the cage overnight. A camera was placed inside the cage to get the birds in various places around the cage.
When we first see the woman holding the rat and looking over a ledge, the actress has handled the rats over the course of multiple months of filming and was comfortable holding him. The trainers were off camera and one of them rewarded the rat between takes. Same type of action when we see her holding the rat on the bus.
When we see the actress walk down the corridor with the rat on her shoulders, the rat was placed on the shoulder of ratcatcher.The actress walked down the hallway which is approximately 15′ with the rat facing forward on her shoulder. In-between takes the rat is taken off her shoulder and held against her chest.
In the scene when the squad is in the guerrilla camp and we see chickens in the background, two chickens were brought to set in a wire cage by trainers and tethered at their marks. Water based smoke was used in the hut near the back of the set about 25 ft from the nearest chicken and a fan was used in case smoke approached the chickens.