Tag Archive for: barn owl conservation

Mark

Plastic Barn Owl Boxes Versus Wooden: A Clear Choice

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Plastic Barn Owl Nest Boxes Versus Wooden: A Clear Choice

The molded plastic heat resistant Barn Owl Box is now being used by thousands of farms and properties.

In 2009, I was a field researcher and animal trainer for the Pittsburgh Zoo. In conjunction with Moraine Preservation Fund, we had erected over 200 wooden nest boxes in PA; however an inspection a few years later revealed many of them were rotting. The immense amount of work seemed wasted and no one had the money to build and erect replacements.

At that time I also spoke to the sustainable director for a large farming concern in Florida that had used barn owl boxes. He informed me they had given up using them since the weather quickly destroyed their plywood boxes. Similar stories came out of California. Few farms were employing large numbers of boxes, though many had a few. It seemed short-lived wooden boxes were deterring barn owl box programs.

So, over a two year period, I designed the plastic box. The product took off rapidly and we began to see large orders from vineyards and orchards. We also receive repeat orders from wildlife departments of various states. My guess had proven true: when farmers and property owners were offered a nest box that would last, they were more inclined to buy and erect them.

My goal of both conserving the barn owl and reducing the use of poisons seemed realized. To date, we have increased the number of nest boxes in the country by many thousands and this has had a positive impact on barn owl populations. Illinois alone has reported a five fold

Plastic nest boxes fledge large numbers of young

increase in their population. The Florida farms that had discontinued using wooden boxes have now installed over 1000 plastic boxes to controthe large numbers of cotton rats in their fields; they report 100% occupancy.

Our own study in Elk Grove California in 2012 attracted 18 breeding pairs that fledged 66 young on a scant 100 acre vineyard in a single season.

Occupation rate was 75%. The density of barn owls on that parcel of land was one of the highest ever reported.  (Browning, et al. 2016 published by 27th Vertebrate Pest Conference, University of CA Davis.)

Wooden boxes are increasingly being taken over by honey bees

Increasingly we have been receiving evidence of another benefit to plastic barn owl boxes. People with both wooden and plastic nest boxes have been noticing that only their wooden boxes have been invaded by honey bees. (And many such hives are Africanized strains of the bee that are highly aggressive and dangerous to humans.)

Our best guess is that the smooth, impregnable plastic surface does not allow the bees to glue their nest to the walls or ceilings. Honey bees will attack the nest, kill the young, and soon make the nest box uninhabitable except for themselves. And Africanized bees are moving northward. In California they have expanded their range since the 1990’s as far north as Napa County. We still urge caution when inspecting our nest boxes, but so far we have no reports of bee occupation.

Today, the choice remains between wood and plastic, and there is some debate over which may have advantages over the other. As someone who has used many of each in the field, I first want to say that both wooden and plastic boxes attract barn owls in high numbers where barn owl populations are good. That said, here are the pros and cons of each:

Pros and Cons between Wooden and Plastic Barn Owl Boxes

The Wooden Box

Advantages:

  • Can be built at home by do-it-yourselfers
  • Initial outlay is lower
  • Just as likely to attract barn owls as plastic

Disadvantages

  • Deteriorate in as little as two years
  • Need repainted periodically
  • If not repainted frequently, the wood surface makes the barn owl box too hot for fledglings
  • Harbor greater loads of parasites
  • Are heavy to install, requiring two people minimum.
  • Need replaced periodically, erasing the initial savings in costs.
  • To save on expense, many wooden boxes are built too small
  • Wooden boxes are frequently occupied by honey bees and these are often Africanized bees which present a danger to humans

The Plastic Barn Owl Nest Box

       Advantages

  • Far outlasts wooden boxes
  • More economical overall
  • Never needs repainted
  • With heat reflective pigments, double box system, and efficient venting, remains cool in full sun
  • Larger size than most wooden boxes (26 x 17 x 17).
  • Achieves high rates of occupancy and fledgling success
  • Can be quickly installed by a single person
  • Evidence indicates that honey bees (including Africanized strains) do not build nests in plastic boxes due to not being able to glue their nests to the smooth plastic

Conclusion

There is nothing wrong with providing wooden boxes for barn owls. They may be particularly useful for do-it-yourselfers and beginners. But for farms and property owners who want to create reliably long-lasting nest box programs that require very little maintenance, plastic next boxes provide a clear choice.

Please go to www.barnowlbox.com for more info.

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MARK BROWNING

Nevada Barn Owls

Barn Owls in Nevada

Barn owl populations are excellent in Nevada

Barn owl populations are excellent in Nevada

The most arid state in the union, Nevada is comprised of four basic eco-regions. The Northern Basin and Range is generally dry, but range land is widespread and irrigated agriculture occurs in eastern basins between the mountains. The Sierra Nevada in the western part of the state is a high mountain range covered in conifers. The Central Basin and Range contains a great deal of grazing land for cattle. The Mojave Basin and Range is the hottest and driest of the four.

Barn owls range throughout the state at elevations below 5000 feet. They are most common in agricultural areas. In the northwestern valleys, where much hay is grown, barn owls live in high concentrations. Here they nest in the huge stacks of hay bales that farmers assemble for curing before shipping. One problem that wildlife officials face is that often the farmers need to move the hay to market before the barn owls have finished fledging. Teams of wildlife rehabbers do a great deal of work every breeding season in raising and releasing young barn owls that were evicted from their haystacks. In the south central region, good populations of barn owls nest in abandoned hard rock mines. Over ten thousand such abandoned mines exist in the state, and barn owls utilize them frequently, usually nesting within fifty feet of the surface. In the northeastern region, barn owls often carve out nesting hollows in riverbanks.

One other area where barn owls concentrate is in the very southern tip of the state where, oddly, vineyards and fruit orchards have been established in the Mojave Desert.

The main prey animals in Nevada are the long-tailed vole, the mountain vole, the kangaroo mouse, and the kangaroo rat.

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MARK BROWNING

Montana Barn Owls

Barn Owls in Montana

iStock_000020901530MediumBiologist Denver Holt of the Owl Research Institute in Charlo, Montana reports that the first record of nesting in the state was in 1992, a surprisingly recent occurrence. Recently a number of nests have been discovered in the Mission Valley at an elevation of 3000 feet, where fertile soils, pasture, cattle, crops, and a national wildlife refuge contribute to good habitat. Here they nest in natural holes and juniper root systems in the clay cliffs.

The bird is most populous in the Mission Valley that lies within the Mission Mountains, with good possibilities in the Bitter Root Valley, and

Montana barn owls are most common in the western reaches and scattered through the rest of the state

Montana barn owls are most common in the western reaches and scattered through the rest of the state

then scattered in the rest of the state. It may be that other good populations in other parts of the state remain to be discovered, especially in agricultural areas at lower elevations. Although some authorities have cautiously called the barn owl a “rare visitor” to the state, it is clear that the barn owl breeds in the state, with successful breeding pairs in years without heavy snowfalls, and populations nearly wiped out during the worst winters, only to recolonize in subsequent seasons.

The large amounts of pasture, hay, and grasslands provide very adequate hunting, but the northern latitude tends to regulate numbers by severe winters. Undoubtedly the occurrences are scattered, and low in number in most areas. Yet the bird has been recorded year round.

Barn owls are most common in the western valleys and scattered throughout most of the state

Barn owls are most common in the western river and agricultural valleys (Green) and scattered throughout most of the rest of the state (Yellow)

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MARK BROWNING

South Carolina Barn Owls

Barn Owls in South Carolina

South Carolina is an important state for barn owls. Satellite tracking studies of barn owls have shown that a high percentage of young barn owls in the northern states migrate in the fall down over the eastern mountains and onto the coastal plains. Many of them winter in good habitat from the Carolinas all the way along the Gulf states to as far as Louisiana. One such bird flew 450 miles from western Pennsylvania to St. Stephens, South Carolina and hunted along a canal there through the winter, then in spring flew back to a barn in Ohio, sixty miles from its original release point. Besides being an important migration route as well as wintering ground for northern birds, South Carolina has always harbored good resident populations of this big white owl. However, in recent years, with changing agricultural practices, spreading suburbs, and a decline in the numbers of barns, barn owl populations in the state may be declining in some areas.

South Carolina Department of Natural Resources

BNOW NEST BOX BEAR

One of our nest boxes installed by S.C. DNR

In an effort to strengthen state barn owl populations, the South Carolina DNR has been erecting barn owl nest boxes since the mid 1990’s. Their focus has been mainly in coastal areas, particularly areas of salt water marsh and old rice fields, both excellent habitat. They have also begun erecting boxes in areas with grasslands and ponds. Out of 44 nest boxes monitored in 2014, 35 of these were of our plastic design from the Barn Owl Box Company. Overall, the DNR reported that 86.6 % of the nest boxes were either used for nesting (50%) or roosting (36.6%), leading to the conclusion that their nest box program is a very effective management tool for barn owls. This is particularly true because barn owls are cavity nesters, and when barns and large hollow trees are unavailable, nest boxes are an excellent enhancement of good habitat.

The Cape Romain Bird Observatory Project

The Cape Romain Bird Observatory Barn Owl Nest Box Project encourages farmers and property owners along the southeastern part of the state to install barn owl nest boxes. The organization provides nest box plans, and occasionally helps fund materials. Interested individuals can contact them by clicking on the link above.

Prey of Barn Owls in South Carolina

One study of 91 pellets taken from eight nest boxes in salt water marsh habitat revealed voles comprised 63% of prey taken. Another 19% was comprised of rice rats, with black and cotton rats making up another 3%. Rice rats are a major pest in grain fields, and barn owls have excellent potential to help lower their numbers and lower crop damage in fields where rice is grown.

Occurrence of Barn Owls in South Carolina

BNOW FORAGING HABITAT 2

Marshlands provide excellent habitat for barn owls

Barn owls likely occur throughout the state, however the heaviest populations occur in the counties along the coast, with barn owls mostly scarce in the Piedmont. Other robust populations appear to be in the central part of the state particularly in Calhoun, Clarendon, Sumter, and Lee Counties. These areas are largely rural and agricultural. Another area with reliable reports is from Anderson County – these sightings have been on farms with hay and pastureland. Regions of pine plantations, heavy forest, and fields of cotton, soy, and corn provide poor habitat for the barn owl.

Attracting Barn Owls with Nest Boxes in South Carolina

Barn owls keep a keen eye out for potential new nesting sites, and as long as you live in an area with hay, pastureland, grasslands, or wetlands, you stand a good chance of attracting a pair of these beautiful birds. Biologists throughout the barn owl’s range encourage residents to install nest boxes in good habitat. If indeed you do succeed in attracting barn owls, contact the South Carolina DNR which monitors state populations.

A special thanks to wildlife biologist Mary-Catherine Martin of the South Carolina DNR for providing valuable information for this article and both photographs.

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