Dietary biology of the tawny owl information

The tawny owl (Strix aluco) is an opportunistic and generalized predator. Peak hunting activity tends to occur largely between dusk to midnight, with owls often following an erratic hunting pattern, perhaps to sites where previous hunts were successful.^[1][2] When feeding young, hunting may need to be prolonged into daylight in the early morning.^[3][4][5] Based on hand-reared young owls that re-released into the wild, hunting behaviour is quite innate rather than learned.^[6] Normally this owl hunts from a perch.^[7][8][1] Perching bouts usually last from about 8 to 14 minutes depending largely on habitat.^[2] Tawny owl's hunting from a perch or pole can recall a buzzard and the two take similar prey sizes as well. However, high initial speed and maneuvering among trees and bushes with great dexterity may allow it to surprise relatively large prey, more like a goshawk.^[7][8] The tawny owl is capable of lifting and carrying off in flight individual prey weighing up to at least 320 g (11 oz).^[9] Their middle talon, the most enlarged claw on owls, measures an average of 19.1 mm (0.75 in). While not as large as those of the Ural owl, the talons are extremely sharp, stout and quite decurved. The claws are considered to be visibly more overdeveloped than those of other European mid-sized owls and the footspan including the claws is fairly larger as well, at an average of about 13.4 cm (5.3 in).^[7][10][11] The hunting owl often extends its wings to balance and control prey upon impact.^[12] Alternatively, this species may hunt from flight. This occurs from 2 to 3 m (6.6 to 9.8 ft) over the ground, often over open habitats such as bushes, marsh or grassland, forming a quartering or zigzag pattern over the opening. During these flights they cover about 30 to 50 m (98 to 164 ft) before changing direction.^[13] Hunting from flight was surprisingly prevalent in a Swedish study of two radio-tagged birds, with 34% of study time spent hunting from flight while 40% of the study time was spent on hunting from a perch.^[13] In a similar study in England, less than 1% of time was spent hunting from flight.^[2] In a more deliberate variation of hunting from flight, the hunting owl may examine crags and nest boxes or also hover around prey roosts. In the latter type of hunts, the tawny owls may strike branches and/or beat their wings together in front of denser foliage, bushes or conifers in order to disturb and flush prey such as small birds and bats, or may dive directly into said foliage.^{[7][12][14][15]} Hovering has also been recorded in differing circumstances, including one incidence of an owl hunting a small bird that was caught on the wing after a hovering flight.^[16][17] Tawny owls have also taken bats on the wing as well (such as ones snatched from near streep lamps when attempting to hunt themselves) and have been seen to hawk large, relatively slow-flying insects such as some beetles and moths in flight.^[7][14] Caterpillars may too be taken from trees.^[14] Usually these hunting variations are correlated with poor weather hampering the capture of preferred prey.^[1][18] Tawny owls eat worms with relative frequency, as they often hear them apparently from below the surface and snatch them up from shallow dirt or below leaf litter. Their worm-hunting style recalls worm hunting techniques by most other birds and they were recorded to eat 0.39 worms per minute during an hour of observation in England and were sometimes seen to feed on worms during daylight.^{[7][19][20][21]} Other hunting from the ground has been observed, often of insects such as beetles, but tawny owls have also been reported to "leap" upon from a ground vantage point in order to capture a vole, quite like foxes often do.^[7][22][23] There are now many accounts of tawny owls feeding on carrion from a wide range of sources, including hares, rats, sheep, and trout.^{[24][25][26][27]}

Upon capture, small prey like shrews and rodents are often swallowed whole, while others may be torn into pieces. Often prey is dismembered in order to more easily ingest it whole, i.e. decapitating mice, removing the legs from frogs while birds like sparrows are also regularly decapitated (with the head often eaten separately) and nearly all avian prey is plucked before being consumed.^{[7][28][29][30]} One tawny owl was observed to eat a squirrel by leaving the head intact and peeling the skin back from the neck, apparently leaving bones in place while consuming the flesh.^[31] Indigestible items, including fur, feathers, bones (which sometimes visibly protrude out of the peller), sometimes intestines and invertebrate carapaces, are regurgitated in large pellets, that can be anywhere in typical size from 20.3 to 67 mm (0.80 to 2.64 in) long with a diameter of 17 to 30 mm (0.67 to 1.18 in). The pellets are typically grey coloured and are found in groups under trees used for roosting or nesting. At least some tawny owl pellets can measure up to 84 mm (3.3 in) long and can include large objects such as an intact 10 cm (3.9 in) bill of a snipe.^{[7][1][29][32]} Undigested material coughed up often reveals different prey than pellets.^[7] Estimated daily food requirements for a tawny owl is 73.5 g (2.59 oz), which is proportionately lower (at about 14% of their own body mass) than the estimates for other medium-sized owls in Europe (at 23–26% of their own body mass), therefore tawny owls can appear to live off of relatively little food quite efficiently.^[33]