Variation in egg weight in the Bengalese finch (Lonchura striata var. domestica)

Abstract

Variation in egg weight was examined in 29 clutches (155 eggs) from 14 pairs of captive Bengalese finches. For clutches of four and seven eggs, egg weight varied more within than among clutches. The opposite was true for clutches of five, six, and eight eggs and when all clutches of four to eight eggs were pooled. Egg weight increased linearly with laying sequence for clutches of four, five, and eight eggs, and for clutches of four to eight eggs combined. Egg weight also varied with clutch size: large clutches contained heavier eggs throughout the clutch than did small clutches. Egg weight was not correlated significantly with the amount of food eaten around the time of egg laying. Furthermore, food consumption did not increase linearly through the laying sequence as did egg weight. These patterns suggest that complex investment allocation decisions underlie egg weight variation in the Bengalese finch.