Under undomesticated conditions, poultry lay eggs in simple nests, perch in trees and spend much of the day scavenging for feed. Chickens spend a large proportion of their time scratching to expose hidden food. Under the backyard and semi-intensive production systems, poultry are usually enclosed at night to discourage thieves and predators, and under intensive production, are totally confined day and night. Some village households keep their few chickens inside the house or even under their bed at night, to discourage theft.
Given a choice of a place to lay their eggs, hens will choose a soft “litter” base, and they prefer an adequately sized (a cube of approximately 30 cm), darkened nest with some privacy. Prior to laying, hens usually investigate a number of possible sites before entering a nest box. They then show nesting behaviour, which includes a special protective nest-seeking voice, after which they sit and finally lay. When they have laid an egg, they announce this with another type of “pride of achievement” call. These calls can also be heard in a battery cage house. If perches are provided, hens will perch most of the time rather than stand on the wire floors, and after dark most birds roost on the perches. Perching is a probable survival characteristic to avoid night predators. The basic requirements for poultry housing are:
space;
ventilation;
light; and
protection
