While most eggs are oval and have a camouflage pattern, there are variations. Eggs laid out of sight in dark holes, for example, are white. Gamebirds and owls lay spherical eggs, while wading birds lay pear-shaped eggs. Aerial species such as Swifts have narrow bodies so they lay longitudinal eggs. The pear shape of the Guillemot’s egg prevents it from rolling of the narrow cliff ledge it is laid on.
THE HATCING PROCESS
Chicks call to each other and to their parents from within the egg, helping to co-ordinate their hatching. They use a tiny “egg tooth” on the bill tip to break the shell and then struggle until they push the two ends apart.
A bird’s life, behavior and appearance revolve around finding a mate and producing eggs in order to ensure the survival of its genes. The nest is a safe place to lay those eggs, incubate them, and raise the resulting brood, so individuals will spend time locating and building the perfect nest for their situation. Birds use nests to protect eggs and nestlings from predators and adverse weather. To minimize predation, birds may use or build nests that are inaccessible, hidden, or camouflaged. Nests may also help keep eggs and nestlings warm.
Types of nests:
Scrape nestsare simple depressions in the ground (sometimes with a few stones added) or in the leaf litter. Such nests are used by some penguins, shorebirds, gulls, terns, nighthawks, vultures (e.g., Black Vulture nest below), and other species.
Burrow nestsare very effective at protecting eggs and young from predators & maintaining an appropriate microclimate for eggs & young. Some birds, like Bank Swallows and Belted Kingfishers (pictured below), usually construct their own burrows, while others, such as Burrowing Owls, may use burrows contracted by other species.
Cavity nests (e.g., in trees or cacti) are used by numerous passerines, woodpeckers, owls, parrots, and some waterfowl. Some birds, such as woodpeckers (like the Gila Woodpecker below), construct their own cavity nests and are referred to as primary cavity nesters. Species that use natural cavities or cavities constructed by primary cavity nesters are called secondary cavity nesters.
Platform nestsare relatively flat nests that may be located on the ground, in a tree, or on the tops of rooted vegetation or or debris in shallow water (like the Western Grebe nest below).
Cupped Nests are, of course, cup-shaped. Such nests may be constructed of various materials and in a variety of locations.
