 The corn crake is omnivorous , but mainly feeds on invertebrates , including earthworms , slugs and snails , spiders , beetles , <unk> , grasshoppers and other insects . In the breeding areas , it is a predator of <unk> <unk> , which infest <unk> <unk> and in the past consumed large amounts of the former grassland pests , <unk> and <unk> . This crake will also eat small frogs and mammals , and plant material including grass seed and cereal grain . Its diet on the wintering grounds is generally similar , but includes locally available items such as <unk> , cockroaches and dung beetles . Food is taken from the ground , low @-@ growing plants and from inside grass <unk> ; the crake may search leaf litter with its bill , and run in pursuit of active prey . Hunting is normally in cover , but , particularly in the wintering areas , it will occasionally feed on grassy tracks or dirt roads . <unk> material is regurgitated as 1 cm ( 0 @.@ 39 in ) <unk> . Chicks are fed mainly on animal food , and when fully grown they may fly with the parents up to 6 @.@ 4 km ( 4 @.@ 0 mi ) to visit supplementary feeding areas . As with other rails , grit is swallowed to help break up food in the stomach . 
