feed on

"Swifts feed on so-called aerial plankton, bugs and spiders that are swept into the sky by high winds."

"feed on" 以xxxx為食.
例如雅虎字裡:"Sheep feed on grass . "  "羊以草為食"


所以這句話中文英文應該為"褐雨燕以被風捲入空中被稱為空中浮游生物的的的小蟲或蜘蛛為食"