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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

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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hold in common is that such programs need to be relentless in their application–the moment that traps and poisons are withdrawn, rodents resume expanding their population with their high reproductive rate.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

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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.

 

 

Screech Owl Breeding Behavior

Breeding Habits of the Screech Owl

Red phase screech owl in our nest box design

Screech Owl Breeding Season

During the snows and winds between late December and mid-February, male screech owls return to the previous year’s breeding sites. These may be holes in trees or nest boxes. screech-owlHere they reclaim their territory, calling frequently, and roosting in both their nest cavity and in nearby trees. By mid-March, when the trees have begun to bud and crocuses have pushed their way up through the soil, the females join them, returning from whatever hunting grounds they inhabited through the winter. Prior to egg laying, the two engage in frequent calling, mutual preening, and mating.

The females will usually spend a few days roosting in various places around the nesting site. At this time, the male often occupies the nest cavity, calling from within. Then, either the female joins the male or occupies the nest on her own. Once inside, she leaves only at dusk and perches nearby where the male feeds her. Throughout her time in the nest, the male roosts nearby and maintains vocal contact with soft trills. This is an excellent time to observe them.

Screech Owl Eggs

Usually by the third week of March, egg laying begins. Although most owl species lay eggs in two day intervals, screech owls tend to produce their first three eggs on a daily basis. After the third egg, longer intervals take place between laying, sometimes greater than the two day interval. Four eggs is the average for a clutch, but clutches of five and six are not unusual. Like other cavity nesting birds, screech owl eggs are plain white. (The eggs of birds that nest in cavities do not need to be camouflaged like the eggs of open nesters.)

Incubation

During incubation, the female applies a bare patch on her underside to each egg in turn to keep them at the necessary temperature for development. While the female watches over and incubates the eggs, the male hunts the area and faithfully delivers prey. It takes 29 to 31 days on average for the eggs to hatch, so most screech owl broods are hatching as the leaves are unfolding on the trees in late April. Surprisingly, only about 50% to 60% of screech owl eggs hatch. (Many other owls hatch out 80% or more.)

During incubation, the males roost at distances of fourteen to twenty feet from the nest, but at hatching time, the males move in as close as six feet. Once the clutch has hatched, the male then moves further away again. So, keeping an eye on the movements of the male can give good indications of what is happening in the nest.

Young Screech Owl Development

Brooding females take a 10 to 30 minute break from their duties usually twice a night—once around dusk and once around dawn. Such breaks are a good time for the female to preen, defecate, stretch her wings, and interact with the male.

Males always bring their prey in whole or headless at best. It is the female’s role to tear apart the large items into pieces the young can swallow. This is typical among owls. If the male arrives at the nest with prey when the female is taking her break, he simply tosses in the prey whole as usual.

The young screech owls grow fast and take anywhere from 24 to 32 days to reach adult weight with fully formed flight feathers. At this point, the parents indulge in a little encouragement for the kids to leave the nest by withholding food. In fact, they will actually remove cached prey items from the nest at this point to further reduce food availability.

The Fledging Period

Around late May or early June one young screech owl after the other ventures outside, taking short hopping flights to nearby branches. Despite their adult size and fully developed feathers, fledglings cannot fly and rely on a few days dependency to flap their wings and develop the necessary muscles. During this stage, the fledglings tend to group together, waiting for food from both parents. After three to five days, the young are able to make flights of up to thirty feet; and by their second week they can keep up with their parents.

The fledging period of screech owls is the most dangerous time in the birds’ lives. This is when they are most vulnerable to predators and accidents due to their inexperience. The birds must learn quickly to adapt to their immediate environment.

By their second week, they may have moved as much as 300 feet from the nest. Now the young screech owls begin to hunt, insects at first. They are still clumsy, and less successful in catching prey than the adults, but they are learning. This period in which the young remain in the nesting area lasts for eight to ten weeks during which the young birds hone their skills.

Fledgling Dispersal

By August or early September, the birds have become proficient hunters and have learned to avoid danger and are ready to move on to their own territories. They are now taking the full range of prey, from crickets and moths to shrews and mice. Unlike barn owls, which often disperse hundreds of miles, young screech owls do not migrate and only move relatively short distances away from where they were raised. Most yearling screech owls are found breeding  1 ¼ to 2 miles away from their natal area.

Screech Owl Nest Boxes

Screech Owl Box

Our Screech Owl Nest Box

Screech owls are easy to attract to nest boxes. For more info on attracting screech owls and screech owl nest boxes, go to our page on the Screech Owl Nest Box.

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

Post-Model

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.

Owl Feathers and Silent Flight

How Owl Feathers Allow Owls to Fly Silently to Catch Prey

The Feathers of Birds

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Down feathers keep birds warm, especially young ones.

Bird feathers, in general, have to be one of the most amazing creations in nature. The flight feathers of wings and tail enable birds to fly—not glide like flying squirrels—but fly powerfully from one end of the globe to the other. Down feathers insulate birds from cold. Contour feathers keep the birds dry in the rain. Powder-down feathers disintegrate into a talcum like dust that birds use to condition the other feathers.

Each feather is a work unto itself: Radiating out from the central shaft that runs up through the middle of the feather, individual vanes also contain barbs that hook over the next vane, and those barbs in turn have barbules that hook on to the barbs. This sophisticated arrangement makes for a very lightweight yet resilient structure. And when these various vanes and hooks become disorganized, a mere pull of a beak through the feather puts them all back together again.

Bluebird On A Stump

Birds use color to attract mates

Beyond these functions, feathers hold the brilliant, defining colors of sexual attraction. Since birds can see colors, various pigments evolve in feathers to make birds, especially the males, more attractive to lure a mate. But not all colors are pigments produced by the feathers. The reds in flamingos come from the foods they eat. And blues cannot be created inside the feathers, so they are created by the structure of the feathers—the soft brilliant blues of jays and buntings and the metallic sheen of purples and greens on grackles and blackbirds are created by infraction—illusory colors that work just the same.

Beyond displaying color to impress the opposite sex, the feathers of doves, pigeons, hummingbirds, manakins, and nighthawks are used in flight to whistle, hum, and boom to create “song” that attracts potential mates.

The Feathers of Owlsbarn-owl-flying

The feathers of owls have other, owlish purposes. These are refinements brought about by darkness and stealth and the quiet of night. As anyone should know who has ever heard a duck or a pheasant take off, feathers in flight create a lot of sound. Songbirds that eat insects and seeds have little need to be stealthy. The same is true for almost all birds.

Even the leading edge of the wing of a hawk through air creates a discernible sound as do the stiff tail feathers cupped to slow down before landing. But hawks use high speed and surprise to capture their prey in full daylight. Owls hunt in the quiet of night where their favorite prey, rodents, utilize their hearing to detect potential predators. Since rodents have poor vision but relatively good hearing, owls rely on being quieter than a whisper to capture their food. This is accomplished by their special feathering.

While the leading edge of a hawk’s wing is sharp and defined (and thus noisy), the leading edge of an owl’s wing contains a serrated, comb-like structure that breaks up the air as it passed over the wing. This soft combing of the air results in almost no sound being produced. In addition, the feathers of the wings, body, and tail of owls are wider and rounder than those of other birds and, to further reduce sound, they are cloaked in a soft, velvety covering of tiny feathers that also soften their passage through air. The result is almost totally silent flight.

Calling Owls in the Wild to Experience their Silent Flight

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Red-phase Screech Owl

Try using a tape of owl calls to call in common owl species in your area. You will notice that, if you do not happen to glimpse the owls arriving, the first thing you will hear will be their singing in response to the tape. They will arrive soundlessly, like ghosts. Their prey also never hears their arrival and must rely on their poor eyesight under dim conditions to detect danger from owls.

The combination of silent flight and excellent hearing creates a perfect nighttime predator in owls.

Barn Owl Boxes for Sale at Discount Prices

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DISCOUNT BARN OWL BOXES

The Barn Owl Box Company provides substantial discounts on our cutting-edge nest boxes for quantity purchases. Our molded plastic nest boxes for barn owls were designed by a leading owl researcher. They are lightweight, long-lasting, very simple to install and maintain, and remain cool in full sun.

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The Barn Owl Box Company Pole Model

The Post Model, our most popular model, features a landing ledge and perch, a rain guard over the entrance hole, an acrylic viewing window in the rear, and comes with all of the hardware for mounting to a metal or wooden pole or post.

The Post Model actually consists of two boxes: a dark liner slides into the white outer box to keep the box dark for the owls. An airspace between the two helps keep the box cool in full sun. This nest box will far outlast wooden nest boxes.

Quantity Discounts for Farmers

Nest boxes surrounding Vino Farms

Researchers recommend one barn owl box for every ten to twenty acres

As a promoter of using barn owls for natural rodent control programs, we lower the prices for farmers who need to erect multiple boxes to achieve control over populations of rodent pests. Numerous research projects have shown that a density of one box for every ten to twenty acres is optimum for integrated pest management programs.  Many vineyards and orchards have achieved this level of barn owl density to reduce populations of voles and pocket gophers.

We initially designed the Barn Owl Box so that units slid into one another, allowing up to 20 nest boxes to fit on a single pallet. This lowers our freight costs and allows us to discount our barn owl boxes considerably for large purchases.

Growers of grapes, citrus, cherries, blueberries, almonds, walnuts, sugar cane, and row crops have all benefited from our quantity discounts. The following price breaks are available:

Discount Sale Prices

Barn Owl Box Pole Model:  Retail Price: $195; 8 to 10 Unit Discount: $180; 11 to 20 Unit Discount: $175.

Savings on a full pallet of Barn Owl Boxes is $400.00. For purchases of more than one pallet, even greater discounts are available.

To inquire about our barn owl box discounts call the Barn Owl Box Company on our toll-free number at 1-877-NESTBOX (1-877-637-8269).

Read more about our Post Model Barn Owl Box.