We’ve got some very noisy tenants living next to us. All’s quiet most of the time but as early evening arrives, the bumping and clattering, bickering and clamouring for attention starts, dominated by a chorus of hissing and screeching. Not quite as inspirational or soothing to listen to as some of the other local feathered residents, but how privileged it makes us feel to hear them.

After several years of expectant vacancy, this was the year that our homemade barn owl box, erected in the small stone barn adjoining our house, finally attracted some breeding occupants. We’ve known there’s been one bird in there all spring, as we’ve watched it hunt the fields around us on most evenings, which was a special treat in itself. However, we’d seen no evidence of anything more….until last week when my husband was stopped in his tracks by the sight of three barn owls perched on the edge of the barn side opening. Further tentative inspection, quietly peering through a hole in the barn door, confirmed another two birds in there – either another two youngsters or one more young and an adult – so a brood of at least four and possibly five, which is a very healthy average. It was a revelation that made our day, our week, and will probably be in the top ten memorable events of the year. I was beyond excited, and just can’t get enough of watching one or more of them sitting at the barn entrance while they wait for Delivera-twit-twoo (apologies for that painful pun, and apologies to those who point out that barn owls don’t actually go ‘Twit-twoo’!).

I always feel privileged when any birds choose to nest around our house – swallows in the barn, redstarts, blue tits and great tits in the next boxes, pied wagtails in the honeysuckle, wrens in the shed, starlings in a tree hole, blackbirds in the willow (although jackdaws in the chimney were slightly overstepping their welcome!) but having barn owls seems so much extra special. I’ve been collecting the pellets (indigestible fur and bone prey remains that are magically sorted within the owl’s gizzard and then regurgitated in a neat, dry oval package) deposited on the barn floor by our resident bird for several months now. These are then proudly presented to John, our Education Officer. Fortunately, John gets just as excited about packets of owl sick as I do, and is always grateful to receive them, adding them to his collection in the freezer ready for visiting school groups. Picking apart the pellets is an exciting voyage of discovery for budding naturalists and forensic ecologists, as they can see exactly what the owl has been eating from the remnant bones and teeth of each small furry victim.

In the UK, the barn owls’ main diet is voles, augmented by other small mammals, and occasionally amphibians and invertebrates. Vole populations are cyclical, showing peaks and troughs over a cycle of several years, a trend which is usually reflected in the abundance of its main avian predators including barn owls, kestrels and short-eared owl. The general perception seems to be that we’re in a vole trough at the moment, making the success of our residents even more gratifying. This success will be helped by the abundance of rough grassland within their hunting territory, which offers ideal habitat for their mammalian prey. Although a lot of the fields around us have now been cut for hay, some remains standing, and there are also plentiful rough grassland margins over which the birds can be seen ethereally floating and swooping.

This spring and summer has offered plenty of perfect evenings for sitting out to watch the barn owls hunting, and more importantly it also means plenty of suitable evenings (and early mornings) for them to be out searching for food. They can’t hunt in heavy rain (their soft feathers have evolved for soundless flight at the expense of waterproofing) or strong wind, so this calm, warm, dry weather has been great for them. Calm, still conditions are optimal for their mode of hunting because they largely rely on sound to find their prey. Barn owls’ ears, hidden beneath their plumage, are set asymmetrically, with one ear high up on one side of its head, and the other low down on the other side. They’d look quite bizarre if their ears were visible but it’s a perfect bit of adaptive evolutionary design which enhances their directional hearing. They’ve also evolved zygodactyl feet – unlike the ‘default’ avian design of three toes facing forwards and one back, they have two facing each way, enhancing their ability to grab and grip their prey.

Our past understanding of the UK barn owl population is rather patchy, with only one UK-wide population estimate made from a national survey in 1995-1997, which estimated 4,000 pairs (+/- 30%). Subsequent annual estimates, based on surveys from local groups across the UK, are collated and published annually by the Barn Owl Trust Current UK Barn Owl population - The Barn Owl Trust, with a healthy picture reported for the last few years. Historically, it’s thought that barn owls have shared the fate of so many of our native avifauna, with agricultural intensification, increased road traffic and the widespread use of environmental chemicals all taking their toll. The prevalence and impact of these chemicals is the particular focus of the Predatory Bird Monitoring Scheme (Predatory Bird Monitoring Scheme | PBMS). Birds of prey, being top of their particular food chain, can provide a way of monitoring the level of chemical contaminants in the environment as whatever is in the environment can end up in their prey and then end up in them. Bird of prey corpses that are found can be submitted to the scheme, which conducts tissue analyses to measure the amount of chemical residue. For barn owls, as with other birds of prey, a particular concern is the use of certain rodenticides which remain active after being ingested by target species, and so risk also poisoning anything that eats them. Partial replacement of these chemicals with ‘second generation rodenticides’, tightened regulation and promotion of their responsible use has hopefully contributed to a reduced impact environmental impact.

For us, we hope that the arrival of a successfully nesting pair in our barn marks the start of an annual event. However, although it may become a routine part of the year, it will never become mundane and will continue to give us the same sense of thrill and privilege to have them there.