Distribution of Dryocopus marutius in Hokkaido, Japan, Based on a Questionnaire

Abstract

A questionnaire on the distribution and breeding of the Black Woodpecker Dryocopus martius was given to 2, 086 persons in Hokkaido in 1987. A total of 1, 929 (92.5%) replies, including 2, 544 observations, were obtained. Of these replies, birds and nests were observed in 716 cases, calls were heard in 142 cases while there were no observations in 1, 060 cases. The number of adult birds counted ranged from 1 to 15 per observation site, and the cases of 1 or 2 bird sightings accounted for 90%. Although at most 4 adult birds were observed in a 5×4.6km quadrat (based on the known distance between neighboring nests), observations of more than 4 birds per quadrat were not reliable. The number of young (or nestlings) observed ranged from 1 to 4, and were within the range of known brood sizes. Breeding was observed in 47 quadrats out of 3, 652 quadrats in Hokkaido. Of those, 43 were in quadrats in which the vegetation was mainly coniferous and deciduous broad-leaved forests, and at altitudes lower than 500m. Black Woodpeckers were observed in 787 quadrats in the breeding season from March to August. Breeding was reported more frequently in coniferous, and deciduous broadleaved forests and mature larch plantations than from other types of vegetation. Including the observations during the non-breeding season from September to February, Black Woodpeckers were recorded in 958 quadrats. The main vegetation types of these quadrats were similar to quadrats recorded for the breeding season. Information about the breeding of the species obtained from the questionnaire is fairly reliable because most cases were based on the presence of young (or nestlings). However, the number of quadrats in which birds were observed were too high, especially at low altitudes, compared with the known distribution of the species in Tokachi district, eastern Hokkaido.