Influence of forced renesting, seasonal date of laying, and female characteristics on clutch size and egg traits in captive American Kestrels

Abstract

Of 78 nesting attempts by captive American Kestrels (Falco sparverius) between 1974 and 1977, 95% successfully renested after removal of the first clutch. Replacement clutches had fewer eggs, longer eggs, and eggs with thicker shells than first clutches. Clutch size, egg length, eggshell thickness, and fresh egg weight declined seasonally. Renesting intervals were shorter in older, experienced layers and clutch size increased by 0.20 eggs with each additional year of age.