UNUSUAL INCUBATION BEHAVIOR AND EMBRYONIC TOLERANCE OF HYPOTHERMIA BY THE BLOOD PHEASANT (ITHAGINIS CRUENTUS)

Birds with single-sex incubation must resolve tradeoffs in time allocated between incubation and foraging by adopting optimal incubation strategies. We used temperature loggers to study the incubation behavior of the Blood Pheasant (Ithaginis cruentus), a uniparental bird of high-elevation forests (3,000 m), at Lianhaushan Nature Reserve in southern Gansu Province, China. The incubation period, 37 days, was 8-10 days longer than for captive birds. Females usually took one recess averaging 6.6 +/- 1.2 h day(-1), only 6.4% of the days had second recesses, and the latter averaged 28 +/- 5 min. Females left the nests near dawn (at 0652 hours, on average) and returned around midday, at 1325 hours; in total, they remained on the nest (i.e., nest attentiveness) for 72.0 +/- 1.4% of the day. Egg predation was not associated with movements of females to and from nests. Egg temperatures dropped rapidly once females left the nest, and eggs often experienced 3.5 h below 10 degrees C for each daily recess. Embryonic hypothermia was thus common, but the hatching rate was >90%. This degree of embryonic hypothermia has rarely been reported. It may be related to the time that Blood Pheasants need to forage on and process their low-quality foods, primarily mosses. Received 7 December 2009, accepted 10 June 2010.