. Bird-lore . yolk has to bestored. The extreme insize of egg as comparedwith the size of thebird occurs among theshore-birds which laybut three or four , the eggs of theUpland Plover areabout twice the size ofthose of the Meadow-lark, though the birdsare about the same size,and those of the SpottedSandpiper are abouttwice the size of thoseof the Catbird. Preco-cial birds like theGrouse, which lay alarge number of eggs,lay relatively smallereggs than the shore-birds. The average num-ber of eggs laid bybirds in temperate clim-ates is four and in thetropics half that num-ber. The number
. Bird-lore . yolk has to bestored. The extreme insize of egg as comparedwith the size of thebird occurs among theshore-birds which laybut three or four , the eggs of theUpland Plover areabout twice the size ofthose of the Meadow-lark, though the birdsare about the same size,and those of the SpottedSandpiper are abouttwice the size of thoseof the Catbird. Preco-cial birds like theGrouse, which lay alarge number of eggs,lay relatively smallereggs than the shore-birds. The average num-ber of eggs laid bybirds in temperate clim-ates is four and in thetropics half that num-ber. The number has doubtless been fixed through the course of naturalselection so that it compares favorably to the number of dangers to whichthe eggs and young are exposed. Thus, sea-birds, like the Murres, thatnest on inaccessible cliffs where there are few enemies, lay but a singleegg, while the game-birds and water-fowl whose eggs and young are exposedto a great many enemies lay from ten to twenty. While the number in a. NEST AND EGGS OF THE SWAMP SPARROW They arc more protectively colored than the eggs of most Sparrows but the pigment is apparently in the process of degeneration and an spotted eggs sometimes occur The Audubon Societies 245 complement is subject to but little variation with each species, it is not atall indicative of the fecundity of the bird, for, when the nest is broken up,birds will ordinarily lay again and sometimes will continue laying throughoutthe season until they are finally successful in raising their young. The caseof a Flicker that laid 71 eggs in 73 days has been cited many times, and it isnot uncommon now-a-days to develop a strain of domestic hens that will layover 200 eggs in a season, though if the eggs are not removed, they ordinarilystop laying and begin to incubate when they have laid fifteen to ^ shape of birds eggs varies from those that are quite longand slender,through those that are oval or sharplyj>ointed, to those that are nearly s
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