olivaceous piculet
A species of bird (Picumnus olivaceus). This is a specialized ornithological term; the name is typically written in katakana.
The olivaceous piculet is a small woodpecker that inhabits Central and South America.
Katakana spelling is standard for this bird name; usually written in kana.
Kanji spelling is rare and mostly found in older or specialized literature; lists it but the word is usually written in kana.
The name is a compound of オリーブ (olive, from English) + 姫 (hime, 'princess', here used as a diminutive prefix for small birds) + 啄木鳥 (kitsutsuki, 'woodpecker'). The exact derivation is uncertain, but it follows a common pattern for Japanese bird names.