Introduction

The Barred Owl (Strix varia) is a bird of prey in the Order Strigiformes and the Family Strigidae. This bird of prey is known by many names, and is also called the Hoot Owl or Eight Hooter, and is sometimes mistakenly called the Bard Owl (Lewis, 2017). First spotted on Vancouver Island in the 1960’s, Barred Owls are now a frequent sight among our forests (Nanaimo News). 

Description and Identification

Barred Owls are large owls with a stocky body and round head. Barred Owls lack ear tufts and have large, dark eyes peering out of a round, grey face. As the name suggests, Barred Owls are characterized by horizontal brown and white bars on the wings, tail, and back, with vertical bars on the chest and underside (Cornell University: All About Birds). Their overall mottled appearance allows them to easily blend in with surrounding tree trunks and branches. 

Barred Owls can also be identified by their unique calls. Barred owls are highly vocal and have a variety of vocalizations, from yelps and barks to their deep, signature call “hoo, hoo, too-HOO; hoo, hoo, too-HOO, ooo“. This is often phrased as “Who cooks for-you? Who cooks for-yooooou?” and can be heard in many forested areas, primarily after dusk (Lewis, 2017). Calls are often heard in bouts of eight, hence the nickname Eight Hooter. It is difficult to distinguish between the sexes of Barred Owls, but a seasoned birder may be able to distinguish a male’s deeper call from that of a female (Lewis, 2017). Although Barred Owls are most active at night, they are known to call throughout the day as well (Audubon). 

Behaviour

Barred Owls are primarily active at night, dawn, and dusk, hunting small mammals, reptiles, amphibians, birds, and invertebrates (Cornell University: Birds of North America). Their preferred method of hunting, called the “perch and pounce” method, includes perching up high and waiting for prey to come to them, from which they will swoop down on silent wings and ambush their prey (About Owls: Owl Research Institute). During the day, you may find them perched among dense foliage, roosting close to a tree trunk and occasionally, hunting or calling. 

As territorial birds, they mostly vocalize to defend their territory. While not as aggressive as Great Horned Owls, Barred Owls are still very protective of their nests, and may chase or strike intruders while hooting (Audubon, Cornell University: Birds of North America). While rare, Barred Owls have been reported to attack humans who interfere with their nest sites (Audubon). 

They are a monogamous species, and you may hear mated pairs calling back and forth to each other through the forest (Lewis, 2017). A courting pair will bob their heads, raise their wings, and call to each other. During courtship, males may also offer the female food (Audubon). Barred Owls nest in cavities or abandoned nests of other animals, and do not make their own nests (Cornell University: All About Birds). A female will lay 2-4 eggs early in the year, between March and April (Lewis, 2017). While the female incubates the eggs the male will bring her food. A pair will likely mate for life, and can defend a nesting territory for many years (Cornell University: All About Birds). 

Distribution and Habitat

Barred Owls are relatively widespread throughout North America, and as non-migratory birds, individuals rarely leave their established territory unless threatened (Cornell University: All About Birds). Despite this, Barred Owls have managed to increase their range in the northwest over the last few decades. Populations now expand south to northern California and north to the southern Yukon in the Pacific Northwest (Kelly and Forsman, 2004). 

Barred Owls can be found in most woodland areas, but seem to favour unfragmented, mature forests near water (Lewis, 2017). Old Growth forests tend to have trees with large cavities that are ideal for nesting, but many populations have been established in younger forests as well (Long and Wolfe, 2019). They prefer swamps and moist environments that can support their diverse diets, but can adapt to a number of habitats if needed (Lewis, 2017). Although they are generally shy of humans, Barred Owls can be seen in urban areas occasionally.

Conservation

Barred Owls are considered a low concern species with a growing population size. Between 1966 and 2014, Barred Owl populations have risen 1.5% per year (Cornell University: All About Birds). As an adult, their only natural predators are the larger, more aggressive Great Horned Owl (Bubo virginianus) (Cornell University: Birds of North America). They are long-lived, and causes of death are usually due to human activities, either directly through vehicle collisions and hunting or indirectly through habitat loss and fragmentation (Lewis, 2017). Because of their preference for mature forests, Barred Owls are sometimes used as indicator species of old growth habitats by forestry management groups (Cornell University: Birds of North America). 

Their spread to the Pacific Northwest has their ranges overlapping with native Spotted Owl (Strix occidentalis) populations (Long and Wolfe, 2019). In many cases, there is evidence that Barred owls out-compete or hybridize with their close cousins the Spotted owl (Hamer et al,, 1994). The displacement of Spotted Owls by Barred Owls is of great concern because Spotted Owls are already considered threatened due to habitat loss (Long and Wolfe, 2019). For this reason, efforts are being taken by wildlife management to control barred owl populations, and plenty of research is being conducted on what makes them so successful.   

The Unfortunate Success of the Barred Owl

The expansion and success of Barred Owls in recent years has unfortunately been problematic to less flexible species, like the Spotted Owl. Competition with Barred Owls is currently considered the biggest threat to Spotted Owl populations (Long and Wolfe, 2019). And with increasing global climate, its expected the Barred Owl will continue to expand its range along the Pacific coast and further invade Spotted owl ranges (Audubon). Barred Owls and Spotted Owls are very similar species, so what makes the Barred Owl so successful over its spotted cousin? 

Competition

Recent research has shown that the Barred Owl is often more aggressive in nature than the Spotted Owl (Long and Wolfe, 2019). As a result, Spotted Owls are often bullied out of their territories by Barred Owls. In an experiment using playback tapes and taxidermy mounts, male Barred Owls were found to respond more aggressively to Spotted Owl playbacks and were more likely to attack Spotted Owl mounts (Long and Wolfe, 2019). In comparison, Spotted Owls were less likely to attack or respond to Barred Owl playbacks and mounts. There are few reports of Spotted Owls attacking Barred Owls in the wild, and few observations of aggressive displays between Barred Owls and Spotted Owls in which the Spotted Owl is the dominant aggressor (Long and Wolfe, 2019). The aggression displayed by Barred Owls in response to Spotted Owl calls may result in the suppression of calling in Spotted Owls when exposed Barred Owl calls (Long and Wolfe, 2019). This might interfere with Spotted Owl courtship displays or drive them from their territory entirely. 

Barred owls have an extensive diet, and will eat most creatures smaller than itself (Lewis, 2017). In comparison, Spotted Owls tend to prey primarily on small mammals, and in some areas they specialize on one main prey source, usually a type of squirrel or woodrat (Cornell University: All About Birds). Because of their picky diet, Spotted Owls can be limited to areas where their prey is abundant. Barred Owls, however, are not nearly as limited. Due to flexibility in their diet, Barred Owls are able to take advantage of many food sources, lending to their success along the West coast (Long and Wolfe, 2019).

Hybridization

Generally, the hybridization of raptors is very rare outside of captivity (Long and Wolfe, 2019). However, there have been reports of hybridization between Barred Owls and Spotted Owls where their ranges overlap. The earliest Barred Owl and Spotted Owl hybridization to be recorded was in 1986 (Long and Wolfe, 2019). Since then, more than 50 hybrids have been reported. While this number may seem inconsequential, hybrids are very difficult to identify and their numbers might be much greater than actually reported (Kelly and Forsman, 2004). The concerns surrounding hybridization is that it may lead to genetic swamping of the Spotted Owl, and eventually lead to a collapse of boundaries between the two species (Long and Wolfe, 2019). 

As mentioned previously, hybrids can be difficult to identify. Typically, hybrids have a checkerboard like pattern of brown and white on their chest, with a white barred head more characteristic of a Barred Owl . Coloration of the top of the wings is lighter than the Spotted Owl but darker than the Barred Owl. The facial disks of hybrids resemble those of Barred Owls except with more brown coloration than the Barred Owl’s typical grey face. The hybrids have a unique vocalization that sounds like a mix of both parents. Their calls are longer than those of Spotted Owls, but shorter than Barred Owls, and consist of 5 to 6 hoots. Hybrids are larger than Spotted Owls and similar in size to Barred owls (Hamer et al., 1994).

In terms of temperament, hybrids more closely resemble Spotted Owls in that they are docile and less wary of humans than the typical Barred Owl (Hamer et al., 1994). Most hybrids occur between male Spotted Owls and female Barred Owls. One explanation for this is that a female Barred Owl is more likely to accept a meal from a male Spotted Owl because they are less picky eaters, whereas a female Spotted Owl might reject a male Barred Owl if he brings her something she wouldn’t normally eat (Long and Wolfe, 2019). 

Parting Thoughts

Barred Owls are magnificent birds. Their resilience and adaptability is remarkable. They are very vocal birds with a large repertoire of sounds which they use to to maintain their territory. However, their flexibility might not be on their side, as they are now seen as a pest in many places in the West because of their displacement of native Spotted Owl populations. Do you think this bird is a menace, or just simply an opportunist?

References

About Owls: Owl Research Institute. (n.d.). Retrieved from https://www.owlresearchinstitute.org/owls-1.

Audubon: Barred Owl. (2019, October 11). Retrieved from https://www.audubon.org/field-guide/bird/barred-owl.

Cornell University: All About Birds. (n.d.). Retrieved from https://www.allaboutbirds.org/guide/Barred_Owl/lifehistory.

Hamer, T. E., & Forsman, E. D. (1994). Hybridization between Barred and Spotted Owls. The Auk, 111(2), 487–492. doi: 10.2307/4088616

Kelly, E. G., & Forsman, E. D. (2004). Recent Records Of Hybridization Between Barred Owls (Strix Varia) And Northern Spotted Owls (S. Occidentalis Caurina). The Auk, 121(3), 806. doi: 10.1642/0004-8038(2004)121[0806:rrohbb]2.0.co;2

Lewis, D. (2017). Barred Owl (Strix varia) – Information, Pictures, Sounds. Retrieved from https://www.owlpages.com/owls/species.php?s=1740.

Long, L. L., & Wolfe, J. D. (2019). Review of the effects of barred owls on spotted owls. The Journal of Wildlife Management, 83(6), 1281–1296. doi: 10.1002/jwmg.21715

Owls in Nanaimo (n.d.). Retrieved from https://www.nanaimo.ca/your-government/news-events/blog/blog-detail/city-of-nanaimo-blog/2015/01/16/Owls-in-Nanaimo.

Sibley, D. (2016). Sibley field guide to birds of western North America. New York: Knopf.