Breeding Habitats and Nest Tree Characteristics of Dryocopus martins in Central Hokkaido

Abstract

Observations were made on nest trees, nesting habitas and breeding of Dryocopus martius in the Sounkyo area, central Hokkaido from 1984 to 1986 and in 1989. All 9 nest trees examined were broad-leaved trees such as Populus maximowiczi, Alnus hirsuta, and so on.Of them 60% were dead trees. The diameter at breast heigh of 8 nest trees ranged from 72 to 105 cm (other 2 nest trees had been cut before we examined them closely). The height of nest trees ranged from 24 to 27 for trees with canopy and from 10 to 12 m for stubs. Most of nest trees inclined towards the entrance side of the nest hole. One to 5 nests were excavated per trees. Nest height ranged from 5 to 18 m above the ground. At the nest sites, tree density ranged from 450 to 2, 150 trees/ha and basal area (the cross section area of tree trunks at breast height) from 18.99 to 58.91 m2/ha. Young fledged in late June or early July.