Diurnal activity-time budget of the black-necked crane, Grus nigricollis, and its behavioral response to human disturbances, in foraging habitats of Bumdeling Gewog & Yangtse Gewog, Bhutan

Abstract

Focal Sampling method was adopted to study the activity-time budget and behavioral response of Grus nigricollis to human disturbances at Bumdeling Gewog and Yangtse Gewog during the winter period, from 29December 2016 to 20 February 2017. A total number of 1932 of behavioral events, amounting to 9,660 minutes, were recorded (1732 adults and 201 juveniles) during the observation period of 48 days. All observations were carried out between 07:30 a.m. and 06:00 p.m. and observation periods of the day were further divided into early morning (07:30 a.m. to 10:00 a.m.), late morning (10:00 a.m. to 12:00 a.m.), early afternoon (12:00 a.m. to 3:00 p.m.), and late afternoon (03:00 p.m. to 06:00 p.m.). The result showed that Grus nigricollis spent more time foraging
(42.1±6.3), followed by vigilance (22.8±6.3), locomotion (18.7±6.4), maintenance (13.4 ±6.2), out of sight (2.2 ±6.3), and resting (0.9±6.3). The diurnal rhythm of different behaviors varied according to time, with foraging behavior reaching its peak at 11:00 a.m., 02:00 p.m, and 04:00 p.m. and resting behavior peaking at noon. The study revealed that Maidung constituted a higher set of threats as compared to Khabretsey and Bategang, with significantly high percent frequency of people and vehicular movement, unregulated tourists and visitors, and disturbances by dogs and livestock. Disturbances were categorized based on the types of disturbances recorded in these regions during the field survey. Grus nigricollis spent more time scanning in the presence of non-lethal human disturbances, however, flight initiation probability increased when approached more directly and closely (<50m). Based on the result of the study, conservation management should initiate public education to reduce unnecessary disturbances by people and initiate community co-management of its site to provide better foraging grounds for the vulnerable Grus nigricollis