1. The oxpecker perched on the back of the rhino, keeping a watchful eye for ticks and other parasites.

牛鹃停在犀牛的背上，警惕地寻找蜱虫和其他寄生虫。

2. The oxpecker's symbiotic relationship with the large grazing animals benefits both parties: the bird gets food, and the host gets parasite removal.

牛鹃与大型食草动物之间的共生关系使双方受益：鸟类获得食物，寄主得到了寄生虫的清扫。