Dietary biology of the Eurasian eagle-owl but none are heavier than the largest mammalian prey that eagle-owls have taken including greater white-fronted goose ("Anser albifrons"), bar-headed goose ("Anser indicus"), great cormorant ("Phalacrocorax carbo"), Himalayan snowcock ("Tetraogallus himalayensis") and demoiselle crane ("Anthropoides virgo"), all averaging around , the swan goose ("Anser cygnoides"), the common crane ("Grus grus") and the (between the dimorphic sexes) great bustard ("Otis tarda"). Eurasian eagle-owls have also hunted adult male western capercaillie, which average about , although usually the much smaller females, at , are more regularly taken. Although they rarely take domestic birds, the range of sizes killed is just as dramatic,
Xylota tarda Russia and the Caucasus then through Russia to Siberia and the Pacific coast (Kuril islands). Old woodland species running on the foliage of bushes and shrubs and on tree stumps and nearby bare ground. The larva has been found in sap runs at the base of the trunk of "Populus tremula" and in rotting wood of "Fagus". Xylota tarda Xylota tarda is a Palearctic species of hoverfly. External images For terms see Morphology of Diptera<br> Wing length 5·5-8·5 mm. Large red areas on black abdomen. Wing membrane not infuscated. Dorso-apical white bristle on metatarsus 1. Antero-dorsal pale hairs on the