Date of this Version
Puchta, S., M.S. Putnam, and K. Maguire. Egg breakage by captive cranes at the International Crane Foundation. In: Folk, MJ and SA Nesbitt, eds. 2008. Proceedings of the Tenth North American Crane Workshop, Feb. 7-10, 2006, Zacatecas City, Zacatecas, Mexico: North American Crane Working Group. p. 170.
Captive cranes can break eggs through deliberate destruction, clumsy parental behavior, or accidentally because of thin shells. We report on the frequency of egg breakage by pairs of captive cranes at the International Crane Foundation (ICF). Among the 15 species of cranes and 1 hybrid female, all except a grey-crowned crane (Balearica regulorum) have broken eggs at ICF. Some pairs broke 1/3 or more of their eggs despite efforts by aviculturists to retrieve them before breakage. We compared the proportion of broken eggs among 7 species where we have data from >5 individual females and more than 150 eggs per species. The total percentage of broken eggs varied by species with Siberian cranes (Grus leucogeranus) having the lowest rate (<1%) and whooping cranes (G. americana) having the highest (13%). Similarly, the proportion of egg-breaking pairs varied among these 7 species from a low 20% of Siberian cranes to 86% of sandhill (G. canadensis) and white-naped (G. vipio) cranes. Anecdotal and circumstantial evidence suggests that most egg breakage is by deliberate destruction. There is currently an ongoing effort to counteract or reform birds that deliberately destroy their eggs.