Articles about the various state barn owl populations with discussions on conservation and use in agriculture.

Wisconsin Barn Owls

Barn Owls in Wisconsin

Barn_Owl_Flying_8349The barn owl in Wisconsin is rare and listed as endangered. Most breeding records have come from the southern counties where the state Bureau of Endangered Resources has attempted to bolster barn owl populations over the years by installing over one hundred nest boxes and releasing captive bred owls. The Wisconsin Department of Natural Resources in recent years has also installed a number of nest boxes.

Although natural grasslands and wetlands have declined in the state and been replaced by row crops such as soy, there are plenty of pastures and meadows remaining throughout the state. A main limiting factor is the severe winters, particularly the heavy snowfalls that regularly occur, making it difficult if not impossible for barn owls to catch prey beneath the snow. Mild winters allow barn owl populations to grow, but a single heavy snowfall that lasts over a week on the ground can severely set back barn owl numbers.

The state of Wisconsin conducted captive breeding program and released 98 young birds into the wild between 1982 and 1987. This program was discontinued since there was no apparent increase in barn owls in the wild. This is typical of such barn owl breed and release programs – due to dramatic dispersal of young in the fall, high mortality, and low returns to natal areas, barn owls are not a suitable species for breed and release. Habitat enhancement, such as nest box programs, have proven to be far more effective.

 

Wisconsin Barn Owl Breeding Records

Wisconsin Barn Owl Breeding Records

Nonetheless, barn owls do breed each year in the state and nest box programs have had some success. The range map is from the Natural Heritage Inventory Base in 2012 and shows counties of confirmed nesting. Keep in mind that such records are dependent on field work which is often limited and that barn owls can be very difficult to detect since they are secretive and nocturnal. Chances are that there are more barn owls than found and that other counties may harbor them. Residents in these or neighboring counties who live in good habitat such as grasslands, wetlands, hayfields, or pasture would be helping conservation efforts by installing nest boxes and contacting their local DNR office when barn owls are seen.

 

Wisconsin grasslands

Wisconsin grasslands

Barn owls in Wisconsin feed mainly on voles (meadow mice) and shrews. They nest in silos, barns, outbuildings, tree cavities, and nest boxes. They breed March through July, laying three to nine eggs, with four or five on average. Researchers believe that most Wisconsin barn owls leave for the winter, but there are records of overwintering as well. It may be the young that disperse in the fall, and the adults that stay, as in many other states.

 

West Virginia Barn Owls

Barn Owls in West Virginia

The South Branch Valley harbors high numbers of barn owls along the Potomac River

The South Branch Valley harbors high numbers of barn owls along the Potomac River

This small, mountainous state, with its extensive forests, provides intermittent, yet excellent habitat for barn owls in its narrow valleys of pasture and hay that spread like numerous fingers between the hillsides. The saving grace of West Virginia farmland is that the steep hills do not afford the chance to farm intensively; always there are plenty of trees, hedges, and fields gone fallow. In the southern portion of the state, reclaimed strip mines also provide good hunting habitat though nesting sites are scarce. Ironically, these machinery-flattened mountaintops revert to wild grasslands where a number of normally rare species find homes, including Grasshopper, Vesper, and Henslow’s Sparrows.

West Virginia is one of those states where barn owls are declared uncommon due only to a lack of surveys. Compounding the problem, most barn owl habitat is located on remote, privately owned farms and researchers must rely on farmers to report the owls.

 

West Virginia Division of Natural Resources

Barn owls raise large numbers of young

Barn owls raise large numbers of young

Biologist Richard Bailey of the West Virginia Division of Natural Resources has seen signs of barn owls throughout the state. He reports that the greatest concentrations of barn owls exist in the eastern half of the state, especially the South Branch Valley (Potomac River), the land surrounding Petersburg in Grant County, and in the Shenandoah Valley that runs through the far eastern panhandle, including Hardy, Mineral, Hampshire, and Morgan Counties. (However, barn owls in the remaining part of the panhandle, Jefferson and Berkeley Counties, are under increasing pressure from development.) He also cites southeastern counties such as Pendleton, Pocahontas, and Greenbrier, and the Ohio River floodplain in the northwestern part of the state as other areas that harbor barn owls in fair numbers. So, in general, good populations exist in the eastern third and the north and west; lower populations are expected in the middle of the state, yet the open valley floors between the mountains still harbor breeding pairs.

Barn Owl Range Map  West Virginia

Barn Owl Range Map
West Virginia

Range Map of Barn Owls in West Virginia

The map shows the abundance of barn owls by county. The orange counties are those with excellent populations due to plenty of open farmland, and numerous farm buildings and silos for nesting. Fair populations live in the yellow areas, and even the gray areas host breeding pairs in the many narrow open valleys between the hills. Even Brooke County at the upper western tip, where barn owls have nested in and around Bethany College for years,  is thought to have a number of this large whitish owl.

West Virginia Barn Owl Breeding Sites and Seasons

Surprisingly, barn owls prosper as high as 3000 feet in the mountain valleys and even more surprising, they have been found breeding anywhere from February to November. So, despite the mountains, barn owls breed here even during winter. Most of the current nesting sites are in hollow trees, silos, barns, abandoned houses, and other outbuildings. Bailey has found piles of pellets four to five feet high in some locations that have obviously been used for decades. Pellet studies show the meadow mouse (vole) to be the predominant prey item, with shrews as the second most important food.

Reporting Barn Owl Sightings

West Virginia biologists are interested in hearing about barn owls in the state. To report sightings, please call the West Virginia Division of Wildlife in Elkins at 304-637-0245 or in Romney at 304-822-3551.

 

 

Delaware Barn Owls

Barn Owls in Delaware

Delaware is a perfect example of how each state seems to have its own dynamic in terms of barn owl populations. Biologist Wayne Lehman, Division

Barn owls most common along the coast

Barn owls most common along Delaware Bay

of Fish and Wildlife, reports that barn owls are found primarily along the coastal salt marshes where their numbers are excellent. He attributes nest boxes to being responsible for a good percentage of successful breeding sites. In the rest of the state, dense human populations, and the relatively sterile environments of soy, corn, and potatoes tend to keep barn owl numbers low.

Plenty of research on barn owls in Delaware has been conducted. Since 1996, Delaware biologists have banded 618 barn owls, including young from 135 nests. In addition, they have captured banded birds from as far away as Blackwater National Wildlife Refuge in Maryland, and birds banded in Delaware have been captured regularly in New Jersey. So, the population of barn owls moves around dynamically, particularly in the fall and spring.

A companion study to the Delaware Fish and Wildlife is being conducted by the Barn Owl Research Foundation across the Delaware River in New Jersey, underway since 1980.

Delaware's salt marshes hold good populations

Delaware’s salt marshes hold good populations

Despite low owl numbers in the rest of the state, residents who live amid good habitat – hayfields, grasslands, and marsh – would be contributing to the conservation of barn owls by installing nest boxes.

Knowing where barn owls are living is of great interest to researchers. If you see a barn owl in Delaware let Jean Woods know so she can add this data to Delaware’s Breeding Bird Atlas. Woods is the curator of birds for the Delaware Museum of Natural History. Contact her at 658-9111, ext. 314 or via email at jwoods@delmnh.org.

Arkansas Barn Owls

Arkansas Topo Map

Barn Owls most common in the green lower altitudes

Barn Owls in Arkansas

Barn owls breed throughout Arkansas. They are most common in the wet agricultural regions of the Mississippi delta in the eastern third of the state. Arkansas grows more rice than any other state in the nation, primarily in the eastern third. Not only is rice good for ducks, it is also good for barn owls. In rice fields they eat primarily cotton rats and rice marsh rats that cause large scale damage to grain crops.

Good populations also thrive in in the flat fertile farmland of the Arkansas River Valley that lies between the Ozark and Ouachita Mountains in the west-central part of the state, and in the Red River Valley in the southwestern counties. The mountainous regions of Arkansas contain the least numbers. Researcher David Clark is asking people to report known barn owl roosts in mountainous Northwest Arkansas. He can be contacted at (501) 590-9559 or by e-mail at dwclark@ualr.edu.

Karen Rowe, biologist for Arkansas Game and Fish Commission, reports “Barn owls in Arkansas nest in old metal grain bins, buildings with grain driers, combines parked in sheds, deer blinds, you name it.” Eggs are usually laid between February and June.

Analysis of 338 pellets from the Holla Bend National Wildlife Refuge in western Arkansas revealed 46.8% cotton rats, 14.2% woodland voles, and 13% marsh rice rats. A smaller sample from eastern Arkansas showed bog lemmings, cotton rats, and voles consumed in that order. However, keep in mind that barn owls will prey upon whatever nocturnal rodent is most prevalent locally.

Post-Model

Post Model Barn Owl Box

Though barn owl numbers are good in many areas, the barn owl is still considered a species of concern here, and residents are encouraged to erect nest boxes to help with their numbers since often the limiting factor to their success is the availability of suitable nesting sites. The rice fields, vineyards, orchards, and row crop farmers of Arkansas could well benefit from nest box programs erected to help reduce rodent pressure on their crops.

Arizona Barn Owls

Barn Owls in Arizona

Common in the entire state, save the northwestern counties of Cococino, Navajo, and Apache, and northern Gila and Greenlee Counties. The high mountains that run in a sharp arc from northern Cococino County down through Navaho, Apache, and Greenlee Counties roughly divide the rather poor populations of the northeastern third of the state from the remaining areas where barn owl populations are excellent. The mountains themselves are virtually bereft of breeding pairs.

Reported nests of Arizona Barn Owls

Reported nests of Arizona Barn Owls

Biologist Troy McCormick of Arizona Game & Fish who contributed to the Arizona Breeding Bird Atlas says they are common in suburban areas and often nest in palm trees. Although no pellet studies have been done yet, he suspects kangaroo and cotton rats in the deserts, and roof and Norwegian rats in the suburbs. People in suburbs often request boxes because they are forced by ordinance to remove dead palm fronds (where they nest). They also nest underground in abandoned copper, silver, and gold mines, under bridges, in stream and drainage banks, and hay stacks. He would not expect them above 6000 to 7000 feet. However, plenty of the altitudes below that have grassy plains, and barn owls are common in the wheat and vegetable farms of the valleys.

Barn Owl Breeding Season in Arizona

Most of Arizona’s Barn Owls are year-round residents but will make local movements during the winter. The birds are generally on their breeding grounds by late winter, and courtship activities such as chasing flights begin at this time. Egg dates in Arizona range from early February to early May. The earliest Barn Owl nest located during the atlas period contained eggs on 10 April. Atlas data suggest that the peak breeding period statewide is from late April through late May. The latest confirmation was a nest with young found on July 24.

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Pole model nest box by the Barn Owl Box Co

They readily use nest boxes where provided, and in Arizona cities and rural communities they will often nest on the dead fronds of untrimmed palms and on the debris collected on branches in tall tamarisks.

Given the good populations being sustained by various natural nesting sites such as cliffs, mines, palms, and tamarisks, attracting barn owls in most of Arizona is easy by installing nest boxes. As our studies have shown, dense populations can also be attracted to areas with high numbers of rodents, especially agricultural regions.

Alabama Barn Owls

Barn Owls in Alabama

Barn owls raise large numbers of young

Barn owls raise large numbers of young

Barn owl populations are excellent throughout the state. With high hay and cattle production in most counties, and salt-water marshes along the coast, barn owls are afforded excellent habitat. Hay and wheat fields are common, with heavy concentrations in the north and the southeast portions of the state. As open field hunters, barn owls will not be expected in the forested areas, however they will settle in cleared areas within forest. They are present in all 67 counties

Their greatest limiting factor is availability of nesting sites. For this reason they are often discovered by hunters nesting in deer blinds. Unable to find hollow trees or barns, barn owls in Alabama enter the woods and seek out the hunting platforms to lay their eggs.

The Alabama Wildlife Center

Post-Model

The Pole Model from the Barn Owl Box Co.

The Alabama Wildlife Center reports a rush of baby owls each spring during deer hunting season. Hunters are often sympathetic to the young owls, despite the ferocious hissing and bill snapping that startled baby owls emit. Usually the wildlife center attempts to relocate the entire family by installing a nest box near the blind and moving the young in hopes that the adults will continue caring for them in the new location.

The non-profit Alabama Wildlife Center helps rehabilitate and rescue thousands of animals and birds every year. To report abandoned, endangered or injured wildlife, or for help relocating barn owls, the center’s hotline is 205-621-3333. Visit online at http://www.awrc.org.

The barn owl is one of four commonly seen owls in Alabama. The great horned, screech, and barred owls all live in good numbers here. The burrowing owl, more common in Florida, is rarely seen. The snowy owl is a rare accidental, as are the long eared and the short-eared owl.

Attracting Barn Owls in Alabama

Alabama’s robust population of barn owls makes the state an excellent place to install a nest box. The barn owl has been shown to consume large

Marshlands provide excellent habitat

Marshlands provide excellent habitat

numbers of voles (meadow mice) in hay and grain fields, cotton rats in sugar cane, and marsh rice rats in rice fields. Farmers of these crops can benefit greatly through using nest boxes in enough numbers to take out large numbers of rodent pests.

 

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.

San Diego Pest Control Using Barn Owls

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5818179-map-of-san-diego-californiaSAN DIEGO PEST CONTROL USING BARN OWLS

As a major metropolitan area, San Diego has its normal fare of urban rodent pests. These are mainly the house mouse and Norwegian rat. And because surrounding San Diego County also contains a great deal of agriculture, even more species of rodent pests are prevalent in the area, doing damage to crops, homes, and other structures. Such pests include the vole, the pocket gopher, and the roof rat.

San Diego Rodent Pests

roof rat 3

Roof rats damage citrus

House mice and rats carry disease, eat large amounts of stored foods, damage wooden structures by their constant chewing, and also damage electrical wiring. Voles inhabit grassland and farmland and cause expensive damage to vines and orchards, consuming fruit and sometimes girdling trees and vines so badly that they perish. Pocket gophers create huge burrow systems, create large mounds that interfere with machinery, and damage crops by chewing on roots. Roof rats live in trees and manmade structures and cause untold damage to citrus and other crops.

San Diego Pest Control

In other words, San Diego is a haven for harmful rodent pests. And there exists an abundance of pest control companies in the region. Such companies offer trapping and poisoning programs, both of which have their limitations. One limitation they hold in common is that such programs need to be relentless in their application–the moment that traps and poisons are withdrawn, rodents resume expanding their population with their high reproductive rate. Another is their relatively high cost per rodent taken. Lastly, poisons invariably find their way into the ecosystem, killing numerous other species of wildlife.

Barn Owls in San Diego

The Pole Model

Click for more info on the molded plastic Barn Owl Box

But the unique and rather amazing barn owl offers a solution that both offers relentless pressure on rodent populations and lower costs and maintenance. A single occupied nest box at an original cost of under $200 will normally house two barn owl adults and four offspring that will, over a year’s time, consume over 1200 rodents. That is a cost per rodent taken at 17 cents each, contrasting strongly with the estimated cost of around $8 per rodent taken by trapping. Each box needs cleaned out only once per year.

And San Diego residents, from farmers to property owners, have been catching on to this growing trend as more and more nest boxes are installed for natural pest control. The solution for pest control using barn owls is simple: install a nest box to attract a pair, and let the barn owls work each night to reduce your rodent pests.

Barn owls are very common in the region, giving San Diego pest control an option that is highly viable, inexpensive, and also helps conserve these beautiful white, golden winged owls. Nest boxes normally achieve 80 to 100% occupancy in their first season or two. Once established, barn owls tend to remain faithful to the area, breeding year after year.

 

Using Barn Owls for Rodent Control in Florida Orange Groves

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    The Florida Citrus Industry

Florida Oranges

Half a million acres of oranges in FL

With approximately half a million acres of orange groves consisting of over 74 million trees, oranges are the largest cash crop in the state of Florida, creating a 64 billion dollar industry. Florida produces most of the juice oranges in the country, leads the nation in grapefruit production, and is second only to California in overall harvest.

Although Polk County in central Florida continues to produce large orange harvests, most of the citrus farms have been relocated to southern Florida where danger of damaging frosts is far less likely.

Rodent Pests in Orange Groves

As with all crops, oranges are plagued by their own attendant rodent pests. The most damaging species of rodent in orange groves is the roof rat, also known as the black rat and, appropriately, the citrus rat. The roof rat originated in tropical Asia, and immigrated to the United States via ocean going vessels. The warm, moist climates of the southern United States allowed this pest to proliferate and it now is the most prevalent rat in many areas, including Florida.

roof rat 3The roof rat is so called because, unlike its cousin, the Norwegian rat, the roof rat lives mainly above ground, nesting in trees and attics, running from place to place along tree branches, and electric and phone lines. Like most rats, it has a high reproductive rate: females produce five to eight young as many as four times per year and, more devastating for farmers, young females can reproduce at ninety days old.

roof rat eaten orange

Roof rats hollow out citrus

Although they are omnivorous, roof rats prefer fruits and nuts as the mainstay of their diet, and the huge swaths of Florida orange groves harbor high numbers of this pest. Damage to the crops can be high. Roof rat damage to citrus is typified by a quarter to half-dollar sized hole where the rat chewed through the skin and then hollowed out the meat of the fruit. Other damage is done to buildings where roof rats chew through electric lines, water pipes, and create holes in walls, floors, and ceilings.

Vield vole (Microtus agrestis)

Voles damage orange trees by chewing on roots and bark

Orange groves are also plagued by various species of mice which, like roof rats, climb trees, chew on blossoms, new growth, and fruit. And voles, also known as meadow mice, feed on the roots and bark of the trees, weakening trees, and sometimes even killing individual trees by girdling them.

The Barn Owl and Orange Groves

As in California vineyards, damage to orange and citrus groves can be significantly reduced by utilizing barn owls in large numbers to reduce rodent populations. Although this practice has not yet caught on in Florida as it has in California, the results in the western vineyards show that it is a trend that is ready to explode in Florida as farmers in various states and countries report very positive results by using barn owls in integrated pest management programs.

Three barn owls about 4 weeks old

Barn owls have high numbers of young

Barn owls are unique as predators in that they are colonial–willing to live within close proximity to each other. This, combined with their high tolerance of human activity, their prodigious appetites, and high production of young, makes them extremely applicable to natural rodent control programs. A single barn owl family will consume thousands of rodents per year.

The Costs of Trapping Rodents Versus Using Barn Owls

Roof rats are most commonly controlled through trapping. As in trapping pocket gophers in California, it is a labor-intensive, costly method for taking out relatively small numbers of rodent pests. A study in California has shown that when costs are compared between trapping pocket gophers and using barn owls to harvest them, the barn owls are hands down far cheaper: after investing in 25 barn owl nest boxes, one vineyard revealed that over a two year period, the cost of using barn owls to take rodents equaled approximately 25 cents each; this contrasted sharply with their estimate of $8 for each pocket gopher taken by human trapping. Similar costs would apply to trapping roof rats versus allowing barn owls to control them.

Barn Owls in Florida

Florida is an excellent place to use barn owls for rodent control since barn owls are very common throughout the state. Richard Raid, a biologist working for U.S. Sugar, once showed the author a barn that housed ten pairs of owls–all raising young in that single barn. The main limiting factor for barn owls in Florida is the availability of nesting sites. Nest boxes are usually occupied quickly with almost 100% occupancy, making it easy to establish a large and effective population of these rodent-eating owls.

Establishing a Barn Owl Nest Box Program

pole-model

The Pole Model made of molded plastic

The beauty of a barn owl nest box program is that it is inexpensive to initiate, and then takes very little maintenance per year to maintain. (Each nest box should be cleaned once per year, a ten minute operation.) And the owl population is self-perpetuating– the owls keep coming back and, importantly, exert a continuous, unrelenting pressure on the rodent population.

Barn owl nest boxes can be erected anywhere the orchard has space to put them: the owls will emerge in the evening and hunt areas where rodents proliferate. Perimeter roads, unused corners of land, and the ends of rows are ideal for erecting boxes and, because barn owls are so colonial, nest boxes can be placed as little as fifty feet apart.

How Many Nest Boxes to Install

Typically, barn owls work best when there are a number of pairs to ensure that the rodent population is kept in check. The basic rule of thumb is one nest box for every ten to twenty acres. Nest boxes can be erected on eight foot poles or posts, enabling easy installation and access. It is best to face them in easterly directions (NE, SE, or E), and to place three to four inches of mulch in the bottom of the box. Other than that, barn owls are highly skilled at spying the entrance holes and soon investigate for potential nesting.

The Florida Orange Grove/Barn Owl Project

We are currently working with several orange grove concerns in Florida to have nest boxes installed in order to demonstrate to citrus growers the potential of using barn owls for natural rodent control in citrus orchards. We will have the nest boxes monitored for barn owl occupancy and breeding success, and we will also have the pellets collected to demonstrate which pest species the barn owls are consuming.

 

 

Barn Owl Nests

Barn Owl Nesting Sites Around the World

Cavity Nesting Birds

Schenks July 16th.wpd

Barn owl broods are large and need spacious cavities.

Barn owls are cavity nesters, just as are many other birds, such as woodpeckers, titmice, chickadees, wrens, and bluebirds. In fact, the 8500 species of birds in the world can be divided into those that nest in cavities and those that build their own nests. (A few species, such as great horned owls, steal other bird’s nests.)

Originally, cavity nesters primarily nested in hollow trees, in caves, and in crevices in river banks, sandstone cliffs, caves, and lava beds. The advantages to being a cavity nester are many:  there is little work to be done in preparation for egg laying; a snug hollow is dryer and warmer than an open stick nest; wind causes less damage to clutches of eggs and broods of chicks; and cavity nests are more protected from predators.

One disadvantage of being dependent on natural cavities is that the birds have to find one large enough for their brood or they cannot breed successfully. In fact, a lack of suitable nesting sites is often cited as the primary limiting factor in the populations of cavity nesting birds. It is hard enough finding a hollow big enough to raise a brood of bluebirds in; but barn owls must find substantially larger cavities and this can create a challenge for these large owls. The other side of this is that cavity nesting bird numbers can be increased dramatically by providing suitable nesting sites.

Barn Owl Nests in Nature

Barn owls are extremely resourceful creatures; and nowhere is this more evident than in their creative choices when it comes to nesting sites. Naturally, throughout the world, they frequently nest in dead trees that contain suitable hollows. In the states of Washington and Oregon, they nest in the nooks and crannies of volcanic cliffs where the cooling lava created the perfect havens. Sandstone cliffs in the American southwest provide much the same with hollows created by wind and rain. In tropical areas, they sometimes resort to nesting on dead palm fronds. In limestone areas they fly into caves and nest on ledges. And in places where there seem to be no trees or cliffs or caves, such as large grassy marshes, they have been known to abandon all care and nest on the ground.

 

Barn owl in burrow

Barn owls even dig their own burrows in river banks and cliffs.

One of the more interesting habits of barn owls is their digging of their own nesting cavities in the clay and earth of river banks and other places where their claws can work the soil. This was unknown to science until recently when researchers, having found barn owls in such cavities many times, actually observed the animals using their claws and feet to create suitable hollows for their eggs and young.

Barn Owl Nests in Manmade Structures

Structures made by humans opened up a whole new world of choices. When humans first began to build thatch-roofed huts, barn owls found their way into the thatch to raise their young. And when barns began to accompany all human settlements, barn owls expanded and increased wherever humans cleared forest, planted crops, and built barns.

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Barn owls frequently nest in hay stacks.

Barn owls have nested in old machinery, grain hoppers, and barrels left on the ground. In the American southwest they will descend as much as a hundred feet into abandoned mines to raise their young. In Nevada and Washington hayfields where farmers create huge stacks of hay bales, barn owls will nest as little as five feet apart in the hollows between the bales.

In Florida sugar cane fields, barn owls often get into trouble when they try to investigate cisterns as potential nesting sites. It was in sugar cane fields that the author was shown a barn that contained seven nesting pairs of barn owls, all with chicks. One pair nested under a wooden ramp made of slats. Another nested on the floor beneath a child’s plastic swimming pool turned upside down. Two others balanced their nests on wide beams. In old silos of the Shenandoah Valley of Virginia, barn owls dig cavities in the old silage where they lay their eggs.

In other words, barn owls will nest wherever they can!

The Importance of Barn Owl Boxes

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The Post Model Barn Owl Box

In parts of the barn owl’s range, a number of changes made by humans have caused barn owl numbers to decline. Dead trees are routinely removed from the landscape. Wooden barns are being replaced by metal barns that do not afford the owls access. And farming has become much more intensive, with few places left that provide good nesting sites for these owls. Yet, in many places, rodent populations proliferate and could support good numbers of barn owls–the main issue is lack of nesting sites.

This is true in almost all types of agriculture, whether it is wheat fields, hay fields, row crops, sugar cane, rice plantations, orchards, or vineyards. In areas of such land use, it is quite possible to attract these owls simply by putting up nest boxes. This can be done in order to create a natural rodent control program on a farm, or for conservation, or merely for the pleasure of having these owls around.

Farmers should take notice of the fact that a single barn owl family consumes between 1000 and 2000 rodents annually and that other methods of killing rodents on a farm, such as trapping and poisons, are far more expensive and time consuming.

For more information, go to our Barn Owl Box Pole Model and Barn Model pages.

Barn Owls in Missouri

Missouri Barn Owls

Almost the entire state of Missouri has good barn owl populations or the potential for them. Barn_Owl_Flying_8349The barn owl is very common along the eastern edge of the state in the interior river lowlands and the Mississippi Alluvial Plain. The northern half of the state harbors good populations in the Central Irregular Plains region where a lot of crops are grown, and the Ozark grasslands in the southeastern part of the state form excellent habitat for barn owls. The eastern Ozarks, where thick forests dominate, have only localized populations in intermittent areas of grassland; the Corn Belt in the upper northwestern corner has low populations at best.

Missouri Barn Owl Populations by Region and County

The Missouri Department of Natural Resources

Bob Gillespie, biologist for the Missouri Department of Natural Resources, says they get a lot of calls about barn owls, especially during the wheat harvest. He notes that they nest in silos, old barns, hollow trees, and nest boxes in Missouri. They have also been known to nest in some numbers in holes in the banks of the various rivers in the state.

Barn Owl Conservation Programs in Missouri 

During the 1980’s the Raptor Rehabilitation and Propagation Project, Inc. (RRPP) and the Missouri Department of Conservation introduced 57 captive-reared barn-owls into St. Charles County, Missouri. The release area was a 900 acre riverine marsh (Marais Temps Clair Wildlife Area) in the Missouri River basin. A few of these birds, identified by their bands, were found nesting in the same area in subsequent seasons.

The World Bird Sanctuary released over 900 captive bred barn owls into Missouri and Illinois during this time as well. Although breed and release programs have in recent years been less favored than habitat preservation and enhancement through nest box programs, these records show that a moderate amount of success can occur when captive-bred owls are released into good habitat.

 The barn owl was recently removed from the Missouri’s list of threatened species.

Missouri Barn Owl Box Programs

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As referred to earlier, conservationists tend to favor habitat preservation and installation of nest boxes over breed and release programs to bolster barn owl populations. The most limiting factor for barn owl numbers in otherwise good habitat is the availability of suitable nesting cavities for this large owl. Today biologists are installing nest boxes in prime habitat and the Missouri Department of Conservation encourages residents to put up nest boxes wherever there are grasslands, wheat fields, hay fields, pasture, or wetlands.

Missouri Agriculture and Barn Owls

The wheat fields and apple orchards of Missouri are excellent candidates for using barn BARN_OWL_ORCHARD_550owls in large numbers for rodent control. Voles (meadow “mice”) cause a great deal of destruction in both crops, eating large amounts of grain, and girdling roots and trunks in orchards. The high populations of rodents in both types of agriculture would likely attract barn owls in good numbers in Missouri. Both wheat fields and orchards are known to be good habitat for barn owls in the rest of the country. Any such nest box programs would contribute to conservation efforts on behalf of this beautiful raptor.

For more information, go to our Product Page, read about barn owls and Integrated Pest Management, and our excellent article on the Economic Value of Barn Owls.

Barn Owls in Washington

Washington Barn Owls

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Barn owls are numerous in most areas of Washington

Barn owls are common in the state of Washington along the entire extension of Puget Sound, along the coast, in the numerous agricultural valleys on both sides of the Cascades, and in the southeastern half of the state. Barn owls are not found to any degree in the Cascades, nor the forested northern mountain counties, but wherever there is agriculture barn owls are found in good numbers. Barn owls even move into large clear cuts where the forest has been cut for lumber.

The river systems, including the Snake and Columbia Rivers, contain good populations that frequently nest in the nearby volcanic cliffs of basalt and lava where vertical cracks and potholes afford excellent nesting sites. In the Palouse Country, where vast quantities of wheat and hay are grown, they are common as well. Here they nest in barns and haystacks. Rehabbers frequently have to bring in nestlings that have been exposed when the hay bales are put on trucks for shipping.

The author once spent a summer harvesting wheat in the Palouse Country. Once the combines passed over the wheat, the farm dogs chowed down on the voles and gophers that were suddenly exposed—and those dogs could barely hold their stomachs off the ground after a day’s eating. This very high number of rodents could support equally surprising numbers of barn owls if enough nest boxes were installed.

Washington Agriculture and Barn Owls

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Orchards attract large numbers of voles, barn owls’ favorite prey.

With almost 40,000 farms comprising 15 million acres, Washington is a major agricultural region. It is first in the nation in growing apples, cherries, pears, and raspberries, and second in the nation in grapes. Orchards and vineyards both attract high numbers of the barn owl’s favorite prey, voles and pocket gophers.

Apple, cherry, and pear orchards are often damaged by voles when these rodents chew on the bark and roots of the trees.

Washington Vineyards and Barn Owls

Washington is second only to California in amounts of grapes harvested. The state grows grapes in all of its agricultural valleys. Many of the regions wine growers use barn owls for natural rodent control and their use is rapidly increasing. Major wine growing regions include the Seattle-Puget Sound Region, Walla Walla Valley, Cascade Valley, Yakima Valley, Pullman-Spokane, Tri-Cities, and the Vancouver-Columbia Gorge. The climates of all of these areas are unique and each produces different qualities in its wines.

Using Barn Owls for Natural Rodent Control in Washington

Nest boxes surrounding Vino Farms

A vineyard surrounded by nest boxes

With the high numbers of barn owls in the state, nest boxes should receive quick and high occupancy. Just as in California, Washington vintners and orchardists can easily attract large numbers of these rodent-eating raptors to their farms, reduce their use of poisons and the labor involved in trapping, and see less damage to their crops, soil, and irrigation systems.

For more information, go to our Product Page, read about barn owls and Integrated Pest Management, and our excellent article on the Economic Value of Barn Owls.