At this time of year it’s possible to see both long and short-eared owls on the same sites in lowland parts of Durham, but it’s unlikely that the relative size of the ears will be any help to you if you are trying to tell them apart.
The short-eared owl (Asio flammeus), a ground nesting species, makes an annual commute to upland areas every spring to breed, returning to the lowlands in the autumn.
Over winter the shorteared owl often forms communal roosts in marshes and wetlands, and individual birds can sometimes be seen in daylight hours flying a few feet above the ground in search of voles, their favourite prey.
The long-eared owl (Asio otus) prefers the safety of a nest in a tree, and their annual commute is the more traditional flight south in the winter rather than upland and lowland.
However, they too like to congregate together in winter months, often favouring blocks of scrub as a communal perch.
As with its short-eared cousin the favourite prey of the long-eared is small mammals, but the two species avoid completion as the long-eared owl is strictly a nocturnal hunter.
Its main rival for prey is the tawny owl.
If you see an owl in flight during day light hours in winter that will be a shorteared owl, but if you see several owls roosting in a tree, all steadfastly ignoring you, they will be longeared owls.
If you can see the longeared’s ‘ears’ you’re too close and disturbing it.