EGG SIZE, SHAPE, AND COLOR
In general, precocial birds' eggs will be a higher percent of their body wieght than will be the eggs of altricial birds. The egg of an American Golden Plover is 50% bigger than a Western Meadowlark egg. Most bird eggs are chicken-shaped. However, some cliff nesters have very pointed eggs so they roll in tight circle.
We assume WHITE EGGS are primitive, since that's the way reptiles are (according to oologists). Eggs are really species specific, yet adaptive significance of egg color is obscure. highly camouflaged eggs (ground nesters) = browns and grays; open cup nesters in trees = blurry shadow marks on blue or white backgrounds; hole nesters = white eggs; and I've mentioned the variably colored eggs of European Cuckoos.
American Golden Plover