Distribution and Abundance of Hazel Grouse in Hokkaido, Japan, Based on Questionnaire

Abstract

A questionnaire on the breeding and distribution of the Hazel Grouse Bonasa bonasia was given to 1, 912 persons in Hokkaido in February and March 1990. A total of 1, 561 (81.6%) replies was obtained. Of these replies, nests and eggs were found in 39, birds were seen in 930, and calls were heard in 316 while there were no observations in 573. More observations were obtained from September to November (11 to 17%) and from May to June (9 to 11%) than in other months. Group sizes ranged from 1 to 30 birds and the cases of 2 birds sightings accounted for 47%. Averages±SD of group sizes were 2.7±1.9 in spring (April and May), 3.4±2.9 (June to August), 3.4±2.8 in autumn (September and October) and 3.3±2.8 in winter (November to March), which were large compared with corresponding values obtained in previous studies in Hokkaido. Nests and eggs were found mainly in May and June. Clutch sizes ranged from 2 to 11 and averaged 5.9±2.4, which was smaller than known clutch sizes in Hokkaido. For this reason small-sized clutches possibly included those of other bird species such as the Nightjar Caprimulgus indicus or the Woodcock Scolopax rusticola because 72% of answerers had not experience of bird watching. Brood sizes ranged from 1 to 10 with an average of 5.4 ±2.1. Of 623 hunters who replied, 224 (36%) hunted Hazel Grouses and the number of birds killed was 4.1±5.7 per hunter. Of birds killed, 532 were males, 340 were females and sex-unknown were 56. Hazel Grouses were observed in 1, 425 quadrats (5×4.6km) of 3, 652 quadrats in Hokkaido. The main vegetation types of these quadrats were coniferous and deciduous broad-leaved forests and larch plantation. Most quadrats in which Hazel Grouses were observed were at altitudes from 200 to 800m. Information about distribution of the species obtained from questionnaries is fairly reliable. However, group, clutch and brood sizes differ from known corresponding values for the species in Hokkaido respectively.