The Cattle Egret, Bubulcus ibis is a small white heron which follows cattle and eats the insects disturbed by them. Their name Bubulcus in Latin means 'herdsman', which is quite apt. The bird removes ticks and flies from cattle. It is a usual sight in Indian countryside to see these birds riding on buffaloes. The egret has been introduced into many countries as it is an effective biocontrol of many parasites of cattle.
There is a downside too to this bird, as it spreads diseases among cattle.