ROUGH GRASS HABITATS: Barn owls, long-eared owls and short-eared owls have a high dependency on small mammals, and in particular the short-tailed field vole. These little mice-like vegetarians live in rough tussocky grassland and in the matted lower level of grass that has formed as a result of the grass’s growing cycle (grow, fold over, grow, fold over etc.) In an average sized field that has not been cut for a couple of seasons, the voles populate the under-story, building a maze of tunnels all over the field, creating their own little ‘vole world’. They will create nesting chambers for breeding and will also have food stores of juicy grass stems at different points. A barn owl’s diet should consist of about 85% field vole, so the creation and preservation of these vole habitats is crucial to their success
FIELD MARGINS: The government has a variety of schemes that pay farmers and landowners to leave land ‘set aside’ for wildlife and also to create field margins - these are crucial vole and wood mouse habitats and managed sensibly will benefit owls. Although a whole field dedicated to voles is a great prospect, it’s not always viable - but an easy compromise is to leave a wide margin at the field edge and this will offer a valuable area for owls to hunt for voles.
MANAGEMENT OF ROUGH GRASSLAND: Careful management of vole habitats is crucial, as the voles need the new juicy grass shoots to feed on, so once a site has established itself, it will eventually get so overgrown that the sunlight cannot get through to re-generate the grass. It is at this point that the grass needs to be cut, but only down to about 8”, ensuring that both the under-story and the voles are not destroyed by the blades of the grass cutter.
There is no real calendar for management, as weather variations will dictate the growth rate of the grass. The best way, on an established site, is to look for signs of voles in the habitat. If there are very few vole droppings or fresh food stores, it will indicate that vole saturation has fallen as the fresh grass growth decreases, and in which case, a cut might be required to bring in light, which will encourage more grass growth and in turn will provide a new source of food to help the voles recover their numbers.
A vole sensitive management regime is the best way to help barn owls - so the simple message is BREED VOLES AND YOU’LL GET OWLS!.
WOODLAND HABITATS: Tawny owls also eat voles, apart from a lot of other things but they also depend heavily on wood mice. In years where woodlands have a good beech mast crop (the fruit if the beech tree) the wood mice numbers boom as a result of a bumper food harvest for them. In turn, this provides greater numbers for tawny owls to feed on and the knock-on effect is that the tawny owls then have a good year, with plenty of food to keep them in good condition and lots of food for their young. These bumper beech mast years are random and not controlled by man - man’s effect on the tawny’s food supply is the management of the woodland floor. All too often, woods are cleared of undercover and, especially in public woods, generally ‘tidied up’.
This takes away cover and nesting habitat for small mammals such as wood mice and in turn reduces the numbers available to the owl. So effective management for owls should ensure that there are enough areas of lightly managed woodland to promote the populations of wood mice, and this will help to sustain the resident tawny owls. Of course tawnys also eat other small mammals, as well as frogs, insects, worms, beatles etc, and these areas will also provide cover for these creatures.
WOOD PILES FOR LITTLE OWLS IN FIELDS: As well as small mammals, insects and the odd small bird, little owls love invertebrates. The creation of a rotting wood pile in the corner of a field will provide a valuable place for little owls to forage for worms, beatles, woodlice etc.