鬣 is rare and literary — you'll see it in classical poetry, zoology terms (鬣狗 liègǒu = hyena, 鬣蜥 lièxī = iguana), and high-register prose. In everyday speech, the more common word for an animal's mane is 鬃 (zōng) or just 毛 (máo).
memory
The character has 髟 (biāo, long hair) on top — the same radical you see in 髮 (hair) and 鬓 (temples). Whenever you spot 髟, expect a hair-related meaning.
