Barn owls are relatively common throughout most of their range and not considered globally threatened.
However, locally severe declines from organochlorine (e.g., DDT) poisoning in the mid-20th century and rodenticides in the late 20th century have affected some populations.
Intensification of agricultural practices often means that the rough grassland that provides the best foraging habitat is lost.
While barn owls are prolific breeders and able to recover from short-term population decreases, they are not as common in some areas as they used to be.
A 1995–1997 survey put their British population at between 3,000 and 5,000 breeding pairs, out of an average of about 150,000 pairs in the whole of Europe.
In the European Community they are considered a Species of European Concern.

In some areas, it may be an insufficiency of suitable nesting sites that is the factor limiting barn owl numbers.
The provision of nest boxes under the eaves of buildings and in other locations can be very successful in increasing the local population.

The Canary barn owl is particularly at risk, and as late as 1975, hunting by fearful locals was limiting the population on Fuerteventura where only a few dozen pairs remain.
On Lanzarote a somewhat larger number of these birds still seem to exist, but altogether this particular subspecies is precariously rare: Probably less than three hundred and perhaps fewer than two hundred individuals still remain.
Similarly, the birds on the western Canary Islands which are usually assigned to the nominate subspecies have declined much, and here wanton destruction seems still to be significant.
On Tenerife they seem relatively numerous but on the other islands, the situation looks about as bleak as on Fuerteventura.
Due to their assignment to the nominate subspecies, which is common in mainland Spain, the western Canary Islands population is not classified as threatened.

In the United Kingdom, the "Barn Owl Nest Box Scheme" is promoted by the World Owl Trust and has many participants in local areas such as Somerset, where a webcam has been set up inside a nest box in which seven young were reared in 2014.
In May 2012, it was revealed that farmers in Israel and Jordan had, over a period of ten years, replaced pesticides with barn owls in a joint conservation venture called "Project Barn Owl".
Barn owls are relatively common throughout most of their range and not considered globally threatened. However, locally severe declines from organochlorine (e.g., DDT) poisoning in the mid-20th century and rodenticides in the late 20th century have affected some populations. Intensification of agricultural practices often means that the rough grassland that provides the best foraging habitat is lost. While barn owls are prolific breeders and able to recover from short-term population decreases, they are not as common in some areas as they used to be. A 1995–1997 survey put their British population at between 3,000 and 5,000 breeding pairs, out of an average of about 150,000 pairs in the whole of Europe. In the European Community they are considered a Species of European Concern.
In some areas, it may be an insufficiency of suitable nesting sites that is the factor limiting barn owl numbers. The provision of nest boxes under the eaves of buildings and in other locations can be very successful in increasing the local population. 
The Canary barn owl is particularly at risk, and as late as 1975, hunting by fearful locals was limiting the population on Fuerteventura where only a few dozen pairs remain. On Lanzarote a somewhat larger number of these birds still seem to exist, but altogether this particular subspecies is precariously rare: Probably less than three hundred and perhaps fewer than two hundred individuals still remain. Similarly, the birds on the western Canary Islands which are usually assigned to the nominate subspecies have declined much, and here wanton destruction seems still to be significant. On Tenerife they seem relatively numerous but on the other islands, the situation looks about as bleak as on Fuerteventura. Due to their assignment to the nominate subspecies, which is common in mainland Spain, the western Canary Islands population is not classified as threatened.
In the United Kingdom, the "Barn Owl Nest Box Scheme" is promoted by the World Owl Trust and has many participants in local areas such as Somerset, where a webcam has been set up inside a nest box in which seven young were reared in 2014. In May 2012, it was revealed that farmers in Israel and Jordan had, over a period of ten years, replaced pesticides with barn owls in a joint conservation venture called "Project Barn Owl".
Western barn owl