Eggs, egg formation and the timing of breeding

The eggs of birds contain all the nutrients necessary for the developing embryo. The female has to obtain these nutrients, and while in some species these may be gathered and stored over a period of time, in many species they seem to be obtained on a daily basis. Obtaining the calcium necessary for the eggshell may pose special problems for some species, which may have to give up valuable feeding time in order to search for calcium. Egg size...