PHOTOPERIOD AND NESTING PHENOLOGY OF WHOOPING CRANES AT TWO CAPTIVE SITES

Increasing day length is considered to be a stimulus to breeding in many avian species in northern latitudes (Welty 1975). Crane species that breed in high latitudes include Siberian crane (Leucogeranus leucogeranus), lesser sandhill crane (Grus canadensis canadensis), hooded crane (G. monacha), and whooping crane (G. americana). The first captive breeding records for hooded and Siberian cranes were induced with the use of artificially extended photoperiods (Mirande et al. 1996). Most likely, cranes that breed in mid-latitudes also respond to increasing daylight. In 1 study, captive greater sandhill cranes (G. c. tabida) were stimulated to lay earlier than controls by using artificial lights to alter the photoperiod (Gee and Pendleton 1992)