High Resolution JPEG Picture of The Tawny Owl or Brown Owl (Strix aluco) is a stocky, medium-sized owl commonly found in woodlands across much of Eurasia. Its underparts are pale with dark streaks, and the upperparts are either brown or grey. Tawny Owls hatch 28-29 days after the egg is laid. The hatch date can be taken as the owl's "birthday" as development in the egg can be seen as broadly equivalent to the embryonic stages in mammals. The nestling stage that follows lasts about 28 days. From about day 25 owlets become curious about the outside world and, although unable to fly, they may leave the nest or hole and hop to nearby perches, a stage known as branching. By day 29 or 30 they have sufficiently developed wings to fly properly, and they are said to be fledglings. Once all her brood have fledged, the mother often takes them away from the nest area and leads them to the parents' main hunting grounds. This owl is non-migratory and highly territorial. Many young birds starve if they cannot find a vacant territory once parental care ceases. Predators of the Tawny Owl include large birds such as Ural and Eagle Owls, Northern Goshawks, Golden Eagles, and Common Buzzards. Pine Martens may raid nests, especially where artificial nest boxes make the owls easy to find, and several instances have been recorded of Eurasian Jackdaws building nests on top of a brooding female Tawny Owl leading to the death of the adult and chicks. A Danish study showed that predation by mammals, especially red foxes, was an important cause of mortality in newly fledged young, with 36% dying between fledging and independence. The mortality risk increased with fledging date from 14% in April to more than 58% in June, and increasing predation of late broods may be an important selective agent for early breeding in this species. [500429613] stock photo
