Breeding status of Mountain Hawk-Eagles in Tokyo, central Japan
Takashi Yamaguchi & Nozomu Mitarai
(Tama Mountain Hawk-Eagle Research Team)
We investigated the breeding status of 15 pairs of Mountain Hawk-Eagles nesting in Tokyo for 12 years from 2009 to 2020 and found that the average breeding success rate was 33.3% during the study period. The habitats of the nesting hawks were categorized into three types according to vegetation within a 1.5 km radius of the nesting site: plantation (mainly conifer) type, broad-leaved forest type, and mixed type of plantation and broad-leaved forest, with breeding success rates of 33.3%, 25.0%, and 38.3%, respectively. Analysis using a generalized linear mixed model (GLMM) showed no significant differences in breeding success by nesting site vegetation type and no trend toward a decrease or increase in breeding success over the study period. 
山口孝・御手洗望 (多摩クマタカ生態調査チーム)
 我々は東京都内のクマタカ15ペアについて, 2009年から2020年の12年間にかけて繁殖状況(幼鳥の巣立ちの有無)を調査した. その結果, 調査期間を通じた全体の繁殖成功率は33.3%であった.
 営巣地から半径1.5km以内の植生を見ると, 営巣地は植林地型, 広葉樹林型, 植林地・広葉樹林混在型の3タイプに分類できた. それぞれの植生タイプの繁殖成功率は, 順に33.3%, 25.0%, 38.3%であった.
 一般化線形混合モデル (GLMM)を用いて分析した結果, 調査期間中に繁殖成功率の有意な増加または減少の傾向は認められなかった. また, 植生タイプ間での繁殖成功率も有意な差は認められなかった.
Vol. 39, pp.101–107, 2023