BREEDING-BEHAVIOR OF ISOLATION-REARED SANDHILL CRANES

During 1988-1990, 38 isolation-reared, color-marked, radio-tagged Grea ter Sandhill Cranes (Grus canadensis tabida) were released into the wi ld at the Seney National Wildlife Refuge (Seney NWR) to develop reintr oduction techniques for Whooping Cranes (Grus americana). The objectiv e of our study was to ascertain whether these puppet-reared cranes dis played normal behavior and to record details of nesting activity. Duri ng 1992 and 1993, 17 cranes (11 males, 6 females) were detected at Sen ey NWR or at more easterly sites in Michigan's Upper Peninsula. We wer e able to monitor sis male cranes; the others had non-functional radio transmitters. In 1992, all six were paired dth wild females, but none nested. In 1993 four pairs nested, all in palustrine habitat dominate d by sedges (Carex spp.) and cattails (Typha spp.). Two nests had two eggs each and one nest had one egg. The fourth nest flooded and no egg s were present when it was checked. Two chicks hatched on 24 May, one on 14 June. Sane survived past I wk. Sex of incubating cranes was know n for 360 h of observation made between 0600-2200 h, 55 Apr.-13 Jun. 1 993, Males incubated for 239 h (66%) of the total samples, females for 121 h (33.4%), Males incubated mostly (77.7%) between 0900-1800 h, fe males mostly in early morning (0600-0900 h) and late afternoon (1900-2 200 h). We conclude that, unlike cranes reared tn the cross-fostering technique, isolation-reared male cranes exhibited normal reproductive behavior. The reproductive behavior of isolation-reared female cranes also must be evaluated.