Habitat Utilization, Time Budget and Daily Rhythm of Ibisbill (Ibidorhyncha struthersii) in Daocheng County, Southwest China

Abstract

The Ibisbill (Ibidorhyncha struthersii) is a rare shorebird uniquely adapted to high-altitude river rapids. Ibisbill has received little study as a result of its isolation and the inaccessibility of its habitat. The habitat utilization, time budgets and daily rhythm of Ibisbill were studied in the southwestern part of Sichuan Province, China, in July to August 2008 and January to February 2010. A total of 55 Ibisbills were recorded in summer and 87 in winter. Encounter rates and group size were similar in summer and winter, but habitat selection differed. In summer, most Ibisbills chose central islands in rivers that had many large stones offering opportunities for both camouflage and physical concealment, and riverside pasture covered by weedy growth with abundant insects making them suitable for foraging. In winter, when water levels are low and many stony beaches are exposed, Ibisbills were more often encountered on riverbanks. Foraging (48.9%) and resting (32.3%) were the most commonly observed behaviors, and the time that Ibisbills spent on foraging (t19 = -4.0, P = 0.001) in winter was significantly higher than in summer. In winter, Ibisbills spent less time engaged in locomotion (t19 = 5.1, P = 0.001) and resting (t19 = -2.8, P = 0.012). Alertness increased toward sunset in summer but not in winter.