Barn owl decline has been witnessed since the 1930’s after the second World War; linked to an increase in intensive agriculture, diminished areas of rough grassland and a reduction in diversity. To combat the deterioration in numbers, barn owls were granted legal protection under the Wildlife and Countryside Act as a Schedule 1 species.
The diet of a barn owl is made up of mainly field voles, common shrews and wood mice, although they are also known to eat amphibians, invertebrates, small birds and even bats -generally scooping up prey at dawn or dusk. Their heart shaped face is used much like a satellite dish that gathers sound and can pin point the subtlest of scuttles or squeaks. Flying around three meters above grassland scanning for prey, their hearing system is extremely effective. In winter the barn owl is more likely to be seen hunting from a vantage point such as a fence post to avoid wasting energy and conserve body heat.
Eating their prey whole, leads to problems in digestion and the inability to process fur and bones which end up being regurgitated in the form of a pellet. Please see the video below on pellet content.
The population of barn owls fluctuates largely depending on the abundance of food and the weather conditions. To be such effective hunters they must fly exceptionally quietly, having extremely soft feathers and maintaining minimal body fat allows them to adopt a stealth approach. The downside of having such delicate feathers is that barn owls are unable to hunt in the rain – fair weather fliers. Being limited to only flying during periods of good weather, in Scotland particularly makes existence extremely difficult. Twinned with naturally low levels of body fat, barn owls cannot sustain long periods without hunting. This leads to a high mortality rate caused by starvation.
An uncommonly known cause of death for barn owls is drowning. This happens because like all birds, they enjoy bathing themselves, but the combination of being unable to gauge how deep troughs and water butts are, as well as their slippery sides, ends in disaster. There are mitigation measures that can be adopted such as purpose made floats which are inserted into troughs. Proactive measures that protect barn owls are encouraged on all sites in addition to adhering to the law.
In construction, the protection of barn owls is important to remain compliant within the law. A barn owl can choose to nest anywhere and once doing so it is a crime to disturb them until the last of the young have become fully independent. Exclusion zones vary depending on the type of nest but it is common practice to implement a 30 metre exclusion on a tree nest.