Barn Owl Housing & Nesting
The Barn Owl is distinctive with buff colored wings, a white breast and relatively long, mostly bare legs. They are easily distinguished from all other owls by their heart shaped face, which is white and fringed with pale, tawny feathers. They lack ear tufts and are only mistaken for other owls in the juvenile stage. Both sexes are flecked with white and black, but females are typically more spotted than males.
Distribution and Breeding Habitat
The Barn Owl is the most widespread owl species in all of North America; in fact, it is one of the most widely distributed of all land birds,found on every continent except Antarctica. Although their range encompasses most of the US and Mexico, breeding pairs are not usually found in more northerly states like New York and Illinois. Within their range, Barn Owls are not found in the most mountainous or heavily forested areas. They tend to prefer open areas like fields, deserts and marshes which are in close proximity to hollow trees, cliffs, riverbanks, or man-made structures, including barns, bridges and other accessible sites.
In spite of the fact that these birds can adapt to both rural and urban habitats, populations have declined in areas that are becoming increasingly agricultural or forested, both of which reduce food availability. Crops of monocultures that do not support rodent populations (such as corn and soybeans), or chemicals which inhibit their growth can also severely limit the numbers of Barn Owls.
Of all the animal’s tested, the Barn Owl ranked first in its ability to locate prey by sound. Their excellent hearing is partly due to moveable ear flaps that change the shape of the feathers around the face and help to amplify sounds. With their remarkable hearing and excellent low-light vision, they can accurately strike and capture prey at night in total darkness. They can even locate prey beneath snow! The Barn Owl’s diet is almost exclusively comprised of voles and other similarity sized rodents, as well as an occasional muskrat, hare or rabbit. Prey is only cached during the breeding season, at which time it is stored in the nest site.
Pair Formation and Territoriality
The territory size varies greatly for different sites and years, but, in general, Barn Owls are very aggressive and can live within ½ miles of each other. Barn Owls are generally monogamous and pairs often stay together for as long as both are alive. Courtship is initiated by males, who begin many different display flights that are often accompanied by clicks, harsh screeches or whistles. Noisy sexual chases often follow the display flights and males are also known to hover in front of females, aptly named “moth flights”. They’ll also show females potential nest sites by flying in and out suitable cavities and, if successful in attracting the female, will begin bringing food to the site. The pair will typically nest at the same site as long as they live.
Courtship generally begins in early winter and the clutches are laid about 1 month after copulation, usually around March. But, in temperate areas, nesting can occur year round.Nesting Behavior Barn Owls do not build actual nests. Females generally create a bed of shredded pellets in cavity sites, and good sites will be reused annually by different breeding pairs.
The cavity dimensions can be so small that barely enough room is available for an incubating female to recline or, it can be as wide as 3 ½ feet, which could accommodate several birds. Nests are almost exclusively located in cavities, ranging from drive-in-movie screens to natural caves. Occasionally burrows will be dug in the soft banks of rivers or arroyos. In areas that contain an abundance of prey, nest boxes and platforms have dramatically improved Barn Owl populations.
Nest Building: None
Egg Laying: Barn Owls lay an average of 4-8 eggs per clutch, and are usually laid at 2-3 day intervals. The eggs are smooth and dull white, although they are often heavily blackened by the contents of the nest lining.Incubation: Only the female incubates the eggs, which lasts forapproximately 30 days. During this time, the male procures all of the food while the female leaves very rarely and only for brief periods.
Nestling Care: Incubation begins with the first egg resulting in different hatching times for young, although females may break off bits of the eggshell to hasten the progress of younger eggs. The shells can either be pushed aside and trampled into the nest lining or eaten by the female. Regardless of other, older chicks, the female will brood, or protect the young until the youngest is about 25 days old. Often, the female will eat feces until the youngest nestling is about 10 days old.
The young are born altricial, or rather poorly developed, with little down and closed eyes. Their capacity for temperature regulation develops slowly, but they can walk by the 16th day and can fly by the 55th. Although there is some squabbling over food, evidence suggests that nestlings may actually share food with their younger nestmates.
The female is solely responsible for feeding of the young, and only tear food into smaller pieces for two weeks, after which the young can swallow their prey whole. The male hunts in solitary until this time, at which point the female joins him. As many as six prey can be delivered to the nest site within 35 minutes. Older nestlings will defecate over the edges of the nest, and the presence of excreta (feces) below the nest site is a good indication that the site was used for nesting.
Once capable of flight, the fledglings roost together and remain dependent upon the adults for 3-5 weeks. During this time, the adults already begin to distance themselves from the young, roosting away from the nest site and interacting with the fledglings only at feeding times. The young become fully independent of the adults in mid-late summer and may wander in any direction until a new suitable location is found.
Winter Movement and Dispersal
Most Barn Owls are non-migratory, except for those living in northerly areas, in which case they may undertake small migrations. Exceptionally cold winters are one of the primary causes of mortality, along with cars, that often collide with recently dispersed young. Sometimes Barn Owls will migrate short distances during food shortages, but exact information about the size of their home range is still unknown.