Mobile Egg Office

The 1.5 kg (3.3 lb) ostrich egg is the largest egg currently known, though the extinct Aepyornis and some dinosaurs had larger eggs. The Bee Hummingbird produces the smallest known bird egg, which weighs half of a gram. The eggs laid by some reptiles and most fish can be even smaller, and those of insects and other invertebrates can be much smaller still.
Bird eggs
Bird eggs are laid by females and incubated for a time that varies according to the species; a single young hatches from each egg. Average clutch sizes range from one (as in condors) to about 17 (the Grey Partridge). Some birds lay eggs even when not fertilized (e.g. hens); it is not uncommon for pet owners to find their lone bird nesting on a clutch of unfertilized eggs, which are sometimes called wind-eggs.