Barn Owl Box Housekeeping

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by MacKenzie Hall, Private Lands Biologist

Barn Own Box Housekeeping
A very productive nest box! Photo by Pat Hilton

I read that a barn owl was once seen delivering 16 mice, 3 gophers, a rat, and a squirrel to a nest in just half an hour.  And after scooping out the contents of a barn owl nest box last Friday, I’m a believer.

The nest box went up as a side-project two years ago, when I was contacted by Rick Wiltraut from the Pennsylvania DCNR.  Rick works with private landowners in PA on barn owl projects and wanted to reach across the river into northern NJ.  The owls are considered a Special Concern species in NJ, with populations trending downward across the region.  The Barn Owl Research Foundation (based in TX) has been monitoring many successful barn owl nest boxes down in Salem & Cumberland Cos for 30 years, but we’re not aware of any such efforts in the farmlands of north Jersey.  So we picked a few farms with good barn owl potential.  

Pat Hilton is always up for expanding her Ark, so her rolling farm in Readington was one that we chose.  We were all ecstatic when a nesting pair moved right in and reared 3 chicks in 2011.   In 2012, the owls got an earlier start (Pat discovered the first hatchlings on Earth Day – nice!).  Before we got a chance to clean out the nest box, the owls were back in business, incubating a second clutch by mid-July!

I spent last Friday catching up on some of the season’s odds & ends, and finally got over to Pat’s farm to clean out that nest box.  Holy puke balls, batgirl!  My little gardening spade and grocery bag were measly equipment for this job.  It took about 15 minutes to chisel through and remove the compacted pellets (regurgitated “undigestibles”) and droppings – two bags worth.  Almost every furry pellet I broke open contained two rodent skulls and the associated skeletons.  Those owls are some busy eaters indeed!

Barn Owl Pellet
Fur and bones – a barn owl pellet. Photo by MacKenzie Hall

Thinking ahead, it would be great to develop a formal barn owl nest box project in northern NJ, similar to what’s been done in south Jersey, and for American kestrels.  Barn owls are limited in part by suitable nest sites, so there’s plenty of room to make improvements for this farm-friendly bird.  Eagle Scouts and interns welcomed!

Oh – and if any biology students out there want to dissect the pellets and analyze the birds’ diet, I will happily bequeath the two bags to you.

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  1. Very interesting. I spoke with MacKenzie, my daughter, right after she cleaned out
    the nest. We were both amazed at what a barn owl brings home.

    MacKenzie is a very dedicated Private Lands Biologist. I am very proud!

  2. Hi Mackenzie,
    My son Jack will be a boy scout next year (webelo 2 this year) and I can see this being a potentially neat project for them. Is there a design somewhere on how to build a nest box for barn owls ?

  3. Hi Rick,
    There are all kind of barn owl box floor plans online – some more complicated than others. I found a pretty simple one at http://www.dnr.state.md.us/wildlife/Habitat/WildAcres/wabarnowlplan.html. Ours have square entry holes (not a big difference), and some designs include “steps” on the inside and a perching platform outside. It’s good to include both if you can. I’d also recommend shelf braces to support the weight of the box.
    Let me know if the scouts end up building some!
    MacKenzie

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