Short-eared Owl: Ecology, Behaviour, and Conservation

Short-eared Owl: Ghost of Open Moorlands

The short-eared owl (Asio flammeus) is one of the most charismatic and conspicuous birds of prey in Britain, regularly hunting in daylight over open moorland, marshes, coastal grasslands, and young forestry plantations. Unlike most owls, short-eared owls are often visible, quartering low over the ground on buoyant, moth-like wings in search of field voles and other small mammals.

UK Population and Status

Short-eared owls are amber-listed in the UK due to declining breeding populations. Around 1,000-3,500 breeding pairs are estimated in Scotland, northern England, and Wales, with numbers fluctuating dramatically with vole population cycles. Winter populations are supplemented by migrants from Scandinavia and Iceland. The species is on Schedule 1 of the Wildlife and Countryside Act, making disturbance of nesting birds illegal.

Ecology and Hunting

Short-eared owls are specialist predators of field voles (Microtus agrestis), which may constitute 50-90% of diet in suitable habitats. Prey populations cycle roughly every 3-4 years, causing dramatic boom-and-bust breeding success for short-eared owls. In lean vole years, owls may not breed or move long distances in search of prey. Brown rats, wood mice, small birds, and invertebrates supplement diet when voles are scarce.

Owls hunt by low, quartering flight with frequent hovering, using exceptional hearing (asymmetric ear placement provides directional sound localisation) and vision. They can locate prey under snow using sound alone.

Breeding

Short-eared owls nest on the ground in dense heather, rough grassland, or sedge tussocks. The female lays 4-8 eggs (clutch size tracks vole abundance), incubating for approximately 26 days. Chicks leave the nest at 12-17 days but remain in the territory until 35+ days. Males hunt intensively to provision the female and young. Broods can be large (5-7) in good vole years, supporting population recovery.

Threats and Welfare Concerns

• Habitat loss: Conversion of rough grassland and heather moorland to improved pasture eliminates hunting habitat
• Afforestation: Young plantations provide habitat initially but become unsuitable as trees mature and canopy closes
• Illegal persecution: Ground-nesting birds are vulnerable to egg and nest destruction, and adults may be targeted on grouse moors
• Rodenticide poisoning: Second-generation anticoagulant rodenticides accumulate in short-eared owls through prey consumption
• Disturbance: Ground-nesting birds are highly vulnerable to disturbance from walkers, photographers, and dogs

Conservation

Conservation management focuses on maintaining and restoring rough grassland and heather moorland habitats, managing vole populations through appropriate grazing, and reducing rodenticide use. Agri-environment scheme payments incentivise rough grassland management. Education about minimising disturbance near nesting sites is important during the March-August breeding season.

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