Meijer T. (1992) Egg-laying patterns in captive Starlings. ARDEA 80 (2): 301-310

Egg-laying was investigated in a captive colony of European starlings Sturnus vulgaris (14 males and 28 females). Clutches (n = 53) were started between 13 April and 2 June, and contained 2-6 eggs. Over the whole breeding season clutch size decreased with progressive laying date (0.029 egg/day). At the beginning of the breeding season, clutches of captive starlings were started less synchronized, compared to free-living starlings (15 days to 3-10 days), and clutch size did not decrease with ca 0.35 egg/day over the first laying period (Karlsson 1983). Starlings had an 'open period' for egg-laying, as described for Galliformes (Follett and Davies, 1979). Eggs of 26 first clutches (n = 115) were laid during the morning hours, 91% between 0800-1200 h. Individual females (n = 26) differed in their interval between laying successive eggs, ranging from 23 to 25 h. Females, with a long egg interval and laying an egg after 1100/1200 h, interrupted laying the next to one day, early in the morning (before 0800 h). Mean egg-weight was not related to female body-weight, but positively correlated with the egg interval. In contrast to most other passerines, weight of the starling eggs decreased with laying order early in the season. Later on in the season this trend was reversed, so that egg-weight increased with laying order. These data serve as framework for further experiments on the proximate regulation of egg laying in the starling.