My relavent observations are on free-range American games and red jungle fowl. Nesting behavior starts a couple days before first egg is layed. Egg laying is cyclical during the 24-h day even before first egg is laid. In days before first egg is layed hens look around for suitable nesting site making the wa-wah-wah sound (egg song). Something is different about sound at this time because sometimes rooster will do similar and push his way into locations that ultimately may be were hen deposits eggs. Rooster also makes sort of a muffled "egg song / tid-bitting" call as he gets into chosen location. Normally rooster's involvement stops before first egg is layed. Hen will scratch out location to make depression and while sitting on nest drag vegetation back to her as she sits on nest. She will also shred material prior to laying an egg in nest each day. First egg follows same process as during search for nest sight although hen normally goes to nest site relatively directly. Egg-song must serve some purpose but I do not know what it is. Duration on nest ranges 15 minutes to 2 hours with birds staying on average about 30 minutes. While on nest hens are very quite, even when tending nest materials. Normally egg depostion is very difficult to detect by watching the hens activity but many domestic hens seem to have difficulties with egglaying process and move around a lot. Following egg deposition the hen sits very tight not making any noise for a few minutes, then she quitely sneaks off holding feathers tight as she walks some disance away (usually > 25 feet). My hens then burst into flight making a cackle (BAWK-BAWK !) sound. The flight can be as short as 50 feet or pushing 200 feet. This behavior may provide two benefits; first is it facilitates hen re-uniting with flock where rooster normally covers (mates with) her immediately, secondly it may distract potential predators from nest by focusing their tracking of her from nest site. Domestic birds do not typically make the long flight after leaving nest any many start making the cackle sound even while on nest.
Nest sites for hens typically in elevated locations with relatively heavy vegetation that is in patches or an edge between to micro-habitats. This protects eggs from flooding during heavy rains, gives hen and nest cover from prying eyes, yet enables hen to escape nest in event she is detected while on it.
My hens, even while brooding, will sacrifice nest to save self. Some will do killdeer thing in effort to distract predator from nest sight. Once eggs pipping many hens will take on some predators during daylight hours. Risk to hen is very high. Game rooster will come to aid of such threatened hens and will even attack fox or small dog. Rooster also at very high risk. Red jungle fowl, especially roosters seem much less likely to engage predators. My dominique hens seem much more inclined to defend nest from predators and thay are also more likely to be lost, especially at night. Dom roosters do not seem to be effective defenders of nest site although they get riled up when hens do.
