{"id":287,"date":"2017-10-06T01:01:10","date_gmt":"2017-10-06T01:01:10","guid":{"rendered":"http:\/\/wordpress.viu.ca\/biol325\/?p=287"},"modified":"2017-10-13T20:04:05","modified_gmt":"2017-10-13T20:04:05","slug":"meet-the-great-horned-owl-bubo-virginianus","status":"publish","type":"post","link":"https:\/\/wordpress.viu.ca\/biol325\/2017\/10\/06\/meet-the-great-horned-owl-bubo-virginianus\/","title":{"rendered":"Meet the Great Horned Owl (Bubo Virginianus)"},"content":{"rendered":"

You probably know them by their large yellow eyes and fluffy appearance, but the great horned owl (GHOW) is a fascinating bird of prey in many other ways. These owls have earned themselves the nickname \u201cTigers of the Woods\u201d and are top-notch silent assassins (Audubon)<\/a>. Located in secondary-growth woodlands, swamps, orchards, and deciduous, coniferous or mixed forests, they can be hard to spot. They usually reside along the edges of open grassland, pastures, and of course, forests (Cornell University: All About Birds)<\/a>. Their mixed plumage coloration and ear tufts help them blend in very well to the surrounding environment. So keep your eyes open for a dark lump on a branch (you can\u2019t miss their yellow eyes)!<\/p>\n

\"\"<\/a>\u00a0 \u00a0 \u00a0Arktos (top) and Danny (bottom) GHOWs from The Raptors in Duncan BC. Photographed by: Christina \"\"<\/a>Youngren<\/p>\n

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One key characteristic of great horned owls is, well, their horns! Rather, they are purely feathers used for camouflage (breaks up silhouette) and communication (raising\/lowering crown feathers). On Vancouver Island, our resident GHOW\u2019s coloration is reddish brown\/white\/black, while on the northern mainland it can vary to white\/grey\/black (Cornell University: All About Birds)<\/a>. We know their eyes are stunning, but there are pros and cons to having them! Owls have many rod photoreceptors (low level vision) and little cone receptors (daylight colour) in their eyes. The result is that these diurnal birds can hunt effectively at night. Their eyes are actually tube-like, and are fixed in their sockets. This means the owl can\u2019t \u201ccross his eyes\u201d, but has high-level distance vision (Jones M.P., Pierce Jr K.E., Ward D.)<\/a>. An owl\u2019s eyes take up ~70% of its skull! Not being able to cross your eyes means you can\u2019t focus on objects up close. To fix this issue, GHOW\u2019s have specialized whisker-like feathers on their face called “filoplumes” to help sense things in close proximity. This leads to the shape of an owl\u2019s face. Special feathers form a facial disk that focuses sound in and acts as a satellite dish. Asymmetric ears on the side of the head make hearing almost 3-D-like. One is down and facing back, the other is up and facing forward\u00a0(Konishi M., 2012)<\/a>.<\/p>\n

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Showing the plumage variation: <\/strong>Arktos (left) and Danny (center), GHOW\u2019s at The Raptors in Duncan BC.\u00a0Photographed by: Christina Youngren.\u00a0(right) https:\/\/www.pinterest.ca\/explore\/raptor-center\/<\/a><\/p>\n

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Specialized facial feathers: <\/strong>Arktos, GHOW from The Raptors. Photographed by: Christina Youngren<\/p>\n

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As far as conservation status goes, the GHOW is of least concern according to the\u00a0International Union for Conservation of Nature (IUCN). Although their overall population is on the decline (33% between 1966 and 2015), they still have a sustainable number to be a successful species. Northern populations fluctuate with predator-prey relationships (IUCN)<\/a>. Owls prey on many mammals (mice, shrews, rabbits, etc.) and other bird species, which can be contaminated with pesticides and poison. These accumulate in the owl and can lead to death (Cornell University: All About Birds)<\/a>. This is still an unfortunate common occurrence today.<\/p>\n

\"\"<\/a>As you can see from the range map above, great horned owls are quite common in the Americas and can be seen year round.<\/p>\n

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Owls are true raptors, and we know this because they have a downward curved beak for ripping and tearing flesh, sharp talons and great eyesight. As you probably already know, owls have silent flight. This is due to the comb-like serrations on the leading edge of the wing feathers (Audubon)<\/a>. The great horned owl use this as their secret weapon of assassination, but as I mentioned above, their eyesight is also a major contributor to their hunting success. A funny fact about owls is that they can actually dance\u2026. the owl dance! This dance is more scientifically explained as them shifting their eye focus on different objects and depths. See for yourself!<\/p>\n