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Ghostly Census-Takers: The Secret Lives of Barn Owls

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We’ve dedicated ourselves to boosting biodiversity in our working countryside, and we’re helped in this cause by the hard-working young people of our Saturday Club and the knowledgeable conservationists who share their expertise with us. Local expert Garry Steele recently led an inspirational and hands-on presentation on owl pellets at the Old School. We caught up with Garry to get the full story.

“I’m at Stickford near Spilsby,” said Garry. “I’ve lived here for 45 years but I grew up in mining country near Ilkeston in Derbyshire. I came to Lincolnshire as a student in 1973 and I do appreciate the difference. I initially didn’t know if I could cope with the flatness, but living on the edge of the Wolds keeps me a bit saner. It’s not the Peak District but you’ve still got a few lumps and bumps.

“I was a keen birdwatcher as a teen. Later on, I volunteered for anything to do with conservation and gradually got involved with bats, newts and barn owls. That led to me spending the second half of my career as an ecological consultant.

“35 years ago, I started putting up nesting boxes for barn owls. That became paid work, and I’d make provision for owls in barn conversions. I’ve also got my own box scheme for raptors locally. I’ve installed over 300 boxes, including a recent 50-odd box project within 10 miles of Lincoln. I’m retired now, the difference being that I’m still busy but I don’t get paid!

“I have a handy guy who makes the boxes while I find the right sites. We sometimes put them up in church towers. The barn owl’s old country name is ‘church owl’. Churches do tend to block access to birds due to increases in species like jackdaws and feral pigeons, but there are ways of controlling access so that only barn owls can get in. We now have 15 church towers in the country with the right permission and access.

“When it comes to siting barn owl boxes, there are three key considerations. First, get away from roads. There are lots of barn owl deaths on roads because they lack peripheral vision. Second, feeding preferences. Ideally, you want lumpy grassland which suits field voles. Cattle are better than sheep as they’re pickier and don’t take the grass all the way down. Third, roosting and breeding. Barn owls originally nested in cavities in old trees. Today, fewer big, decaying trees are left standing and the birds have adapted to us. In post-war Lincolnshire in particular, lots of old, disused premises associated with mixed farming are good for barn owls.

owl pellets

“As a schedule-one species, barn owls require extra protection at or near the nest. Back in the 1980s, their UK population was down to around 4,000 pairs. We’ve doubled or tripled that and we’ve got both farmers and conservationists to thank. Nesting boxes have been crucial and 70% of barn owls are housed in artificial sites.

“Unlike the tawny owl, the barn owl needs a temperate climate and open ground for hunting. As a small, light bird, they prefer areas with lower chances of snow as they’re too light to crash through it onto prey. In the Fens where grasslands have been ploughed out, they’ve learned to hunt in straight lines along water courses where their prey is concentrated.

“Barn owls can struggle with wet weather. For one thing, they locate prey using sound, so strong wind and heavy rain make it hard to discern small movements in the long grass. For another, they have noise-reducing aerodynamics in their feathers – leading edge barbs on the front primary that channel vortices and keep their flight stealthy – that can be compromised when wet. Two or three nights of wild or wet weather can lead to chick mortality, although barn owls are capable of caching food and saving up for a rainy day.

“They’re also famous for their ghostly presence, and they certainly have a horrible screech which is very distinct from a tawny owl’s ‘keewick / hoo-hoo’ duet. If barn owls roost in certain trees, they can pick up a spectral, white glow from bioluminescent fungi. I’m sure barn owls are behind a lot of ghost stories.

“I got involved with examining owl pellets about 30 years ago. We’d get pellets from 35 sites around the county with a view to seeing what the owls had been eating. The first time I saw barn owl chicks at a pellet site, I knew this was for me.

“Analysing pellets is a good way of getting data on small mammal populations. Some distinct patterns emerge. Field voles, for example, have a natural five-year cycle. Their numbers boom one year in five then a natural controlling mechanism kicks in and they become markedly less abundant. Field voles are one of our commonest mammals numbering up to 90-million.

“Looking into pellets is a way of using barn owls as census takers for small mammals. The greater white-toothed shrew has reached our shores and has been found in Northumberland. It outguns the pygmy shrew so could be a problem. There’s a national campaign to keep tabs on it, and barn owls will find them before we do and pass on the data in their pellets.

barn owls

“Barn owls take prey straight into the upper gizzard. Once there, acids break it down, useful nutrients are removed and a muscular action turns hair and bones into a hard pellet which is coughed up. This process isn’t unique to owls – robins can produce pellets – but it’s more pronounced with them.

“Once kids accept the fact that pellets are sterile and dry and aren’t poo, they get fascinated. During one talk, we found seven skulls in one pellet. It’s instant science; you can separate things out and get down to the level of the teeth in a mammal’s lower jaw. Identification through dentition was how we found out a few weeks ago that South Ormsby Estate has water shrews, an excellent sign for biodiversity.

“We need to get children involved at all ages. During the session at South Ormsby Estate, the kids got connected with nature and there wasn’t a mobile phone to be seen. It was particularly heartening to see teenagers getting involved, as schools tend to do less of this sort of engagement after the primary years. The decision-makers of the future need to have a connection with nature from a formative age.

“I’m hoping to come back to the Estate to share more ideas on boxes for barn owls and other raptors, and not just nesting boxes. Barn owls pair for life and they’ll roost in suitable spots all-year round. They don’t care about farm noise if they’ve got good real estate with a network of shelter within their home range.

“I still find the sight of a barn owl magical. I’ll always stop when I catch a glimpse of one. I’m excited by what’s going on at South Ormsby Estate and I look forward to discovering more good news next time I visit.”

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