During 1988-1990, 38 isolation-reared, color-marked, radio-tagged Greater Sandhill Cranes (Grus canadensis tabida) were released into the wild at the Seney National Wildlife Refuge (Seney NWR) to develop reintroduction techniques for Whooping Cranes (Grus americana). The objective of our study was to ascertain whether these puppet-reared cranes displayed normal behavior and to record details of nesting activity. During 1992 and 1993, 17 cranes (11 males, 6 females) were detected at Seney NWR or at more easterly sites in Michigan's Upper Peninsula. We were able to monitor six male cranes; the others had non-functional radio transmitters. In 1992, all six were paired with wild females, but none nested. In 1993 four pairs nested, all in palustrine habitat dominated 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 eggs were present when it was checked. Two chicks hatched on 24 May, one on 14 June. None survived past 1 wk. Sex of incubating cranes was known for 360 h of observation made between 0600-2200 h, 25 Apr.-13 Jun. 1993. 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, females mostly in early morning (0600-0900 h) and late afternoon (1900-2200 h). We conclude that, unlike cranes reared by the cross-fostering technique, isolation-reared male cranes exhibited normal reproductive behavior. The reproductive behavior of isolation-reared female cranes also must be evaluated.
