The sign of his adulthood. 证明他已经成年

177. The scarlet heart.
     那颗红心
178. As a final thrill, he expands the pink crest
     作为压轴节目 他张开了头部后
179. on the back of his head.
     头部后侧的粉色羽冠
180. The sign of his adulthood.
     证明他已经成年
181. But he's made a mistake.
     但他弄错了
182. This is not a female
     这只不是雌鸟
183. but a young male who hasn't yet developed that head crest.
     而是一只还没有长出羽冠的雄鸟

来自《行星地球 第二季 第六集 Planet Earth S02E06 城市》第 180 行