The breeding success of Mountain Hawk-Eagles in relation to environmental factors

Abstract

The Mountain Hawk Eagle Nisaetus nipalensis is listed as threatened under the Endangered Species Preservation Act. Although its recent breeding rate has been considered to be in decline, no broad-based study has been conduced throughout Japan. We studied the breeding rate and related environmental factors from 15 years of data collected by the Ministry of Land and Transport and the Agency of Water Resources from 1994 to 2008. We found that the average breeding rate was 33.2% (N = 512) and that no apparent decline was occurring. Snow depth, beech mast production and breeding success (or failure) of the previous year, were possible environmental factors that affected breeding.