wildlife protection area
A designated area under Japanese law where hunting and capture of wild birds and mammals are regulated or prohibited.
This mountain is designated as a wildlife protection area.
自然保護区 is a broader term for nature reserve, while 鳥獣保護区域 specifically focuses on the protection of birds and mammals under the Wildlife Protection and Hunting Management Law.
Compound of 鳥獣 (birds and beasts) + 保護 (protection) + 区域 (area). A modern legal term.