紅嘴牛椋鳥會食用大型哺乳類動物身上的蟲子。極危的黑犀牛視覺非常差，牛椋鳥除了能替牠除去身上寄生蟲，亦能在發現危險時預警犀牛。研究發現，當黑犀牛身上有牛椋鳥作伴時，能100%偵測到人類的迫近，但當沒有牛椋鳥時則降到23%。因大型哺乳類動物的消失令紅嘴牛椋鳥在部分地區已滅絕，亦令很多黑犀牛失去這些夥伴

Red-billed oxpecker mainly feeds on ticks on large mammals. The critically endangered black rhino has very poor vision; in addition to keep the rhino tick-free, oxpeckers also warn the rhino when they spot danger. Study found a black rhino with oxpeckers can 100% detect human approach, but dropped to 23% if the rhino is without them. due to the disappearance of large mammals, the red-billed oxpecker became extinct in some areas, leaving the black rhino alone without oxpecker companions.

https://www.natureworldnews.com/articles/43652/20200414/red-bellied-oxpeckers-indeed-black-rhinos-body-guards-against-humans.htm