Studies revealed 20th Century population decline
While the Barn Owl population seems to have stabilised recently, the decrease of 69% between 1932 and 1982-85 was very worrying. The main reasons for it are summarised below:
To survive cold winters, Barn Owls need to hunt successfully, and cannot survive long if they do not catch prey often enough. Severe weather can be deadly because it can stop the birds from hunting, as well as reduce prey availability.
Snow cover is a big problem for Barn Owls trying to make it through winter. Too many days of snow cover means not enough chances to find food. Mild winters help the Barn Owls to avoid starvation, and to be in good condition for breeding in the Spring.
While recently many parts of the British Isles have experienced mild winters, during the 20th Century there was actually a weather trend of increasing numbers of winters with over 20 days of snow cover on the ground. There was also an increase in numbers of winters with severe weather. These harsh conditions hit Barn Owls hardest on high ground, where it tends to be colder, and snow tends to thaw more slowly.
LOSS OF WINTER FOOD:
Since the 1940’s, farmers have used combine harvesters, which are very efficient at harvesting grain. Before the combines and sealed grain silos, stackyards were used to store grain, more grain was spilled during harvests, and straw on the ground made a better winter habitat for prey of the Barn Owls, such as mice and rats.
Farms are altogether cleaner places today, with grain stores which are more rodent-proof, and so on.
LOSS OF ROUGH GRASS:
Today farmers are capable of using land which was too difficult to cultivate or manage long ago. Crop fields are larger than in the past, often ploughed right up to the edge, and a great many hedges have been lost from some areas. Also, many wet grasslands have been drained and put in to more intensive use.
Changes like these have taken away rough grassy habitat, which was perfect ground for Barn Owls to find prey.
LOSS OF CONNECTED HABITAT:
Where rough grassy edges have been lost from the banks of canals, rivers, meadows and crop fields, a whole network of hunting grounds have been disconnected. This makes it harder for Barn Owls to establish territories, and harder for them to travel between hunting grounds.
When young Barn Owls leave their parents and need to find their own territory, they may have to travel a long way to find good habitat if the best areas are separated. When older Barn Owls die, other owls in the population can return to “fill the gap” more quickly if territories are connected.
LOSS OF NESTING SITES:
Many old, hollow trees were lost to Elm Disease, and other traditional nest sites like old barns have collapsed or have been lost to development. Actually, it is easy to modernise without losing Barn Owl nest sites, and we can provide information on designs for "owl windows" and "owl towers".
You can help Barn Owls.
Find out how you can change things on our animated CONSERVATION page, and read some of the fact-files about HOW YOU CAN HELP BARN OWLS.