Four linear measurements were also taken daily on the young sparrows. A summary of these data appears in Figure 1.
Behavior
The first indication of hatching is a crack in the side of the egg along the line of greatest circumference. The crack is extended along this line by the egg tooth, and then contraction of muscles of the neck by the embryo separates the shell into two pieces. Extension of the legs frees the bird from the shell. I held the eggs of two Seaside Sparrows in my hand and watched this procedure. In each instance the young bird defecated in the shell before freeing itself. A barely audible "peep" note was heard from one hatchling Sharp-tailed Sparrow when I held it near my ear. When free from the shell, the young birds rest on their tarsi, abdomen and forehead; their down dries in a few minutes, and their skin becomes noticeably darker. One sparrow gaped five minutes after hatching and all the young gaped later the same day. The abdomen of the young becomes distended when they are fed by the parents.
PLATE 5
Ammospiza caudacuta Ammospiza maritima
Drawings of the nestlings of the two species of Ammospiza approximately three days of age showing the variation in the amount and placement of the neossoptiles in the two species. Abbreviations for feather tracts in which downs were found: ca, capital; h, humeral; a, alar; d, d´, dorsal; cr, crural; v, ventral.
PLATE 6
