Good Day For Birds!

All of these pictures were taken on land the University of Colorado and City of Boulder want to destroy.

I know where the owl lives now.

 

Three Kestrels were active this morning at the same time.  Male at the right below.

And a reminder from last spring that winter won’t last forever.

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10 Responses to Good Day For Birds!

  1. Stewart Pid says:

    Great pics Tony. I looked at those ear feathers on the owl and thought they can’t be actual ears and went digging for info and thought I would share. Here is the link if you want to see with the pictures https://www.owlpages.com/owls/articles.php?a=6

    Owl Ears & Hearing
    By Deane Lewis

    Because Owls are generally active at night, they have a highly developed auditory (hearing) system. The ears are located at the sides of the head, behind the eyes, and are covered by the feathers of the facial disc. The “Ear Tufts” visible on some species are not ears at all, but simply display feathers.

    Long-eared Owl
    A Long-eared Owl’s “ears” are not ears, but display feathers. Photo © Cezary Korkosz
    The shape of the ear opening (known as the aperture) depends on the species of Owl – in some species, the opening has a valve, called an operculum covering it . The opening varies from a small, round aperture to an oblong slit with a large operculum. All owls of the family Tytonidae have rounded openings with large opercula, while in Strigidae, the shape of the outer ear is more varied.

    Barn Owl ear
    Ear opening of a Common Barn Owl. Photo © Alan Zieradzki
    An Owl’s range of audible sounds is not unlike that of humans, but an Owl’s hearing is much more acute at certain frequencies enabling it to hear even the slightest movement of their prey in leaves or undergrowth.

    Barn Owl hearing graph
    Hearing sensitivity comparison of Barn Owls, Cats & Humans – As charted by M. Konishi, American Scientist Vol 61, 1973. Both the cat and the Barn Owl have much more sensitive hearing than the human in the range of about 0.5 to 10 kHz. The cat and Barn Owl have a similar sensitivity up to approximately 7 kHz. Beyond this point, the cat continues to be sensitive, but the Barn Owl’s sensitivity declines sharply.
    Some Owl species have asymmetrically set ear openings (i.e. one ear is higher than the other) – in particular the strictly nocturnal species, such as the Barn Owl or the Tengmalm’s (Boreal) Owl. These species have a very pronounced facial disc, which acts like a “radar dish”, guiding sounds into the ear openings. The shape of the disc can be altered at will, using special facial muscles. Also, an Owl’s bill is pointed downward, increasing the surface area over which the soundwaves are collected by the facial disc. In 4 species (Ural, Great Grey, Boreal/Tengmalm’s & Saw-whet), the ear asymmetry is actually in the temporal parts of the skull, giving it a “lop-sided” appearance.

    Boreal Owl skull
    Skull of a Boreal Owl showing asymmetric ear openings. Photo © Jim Duncan Great Grey Owl face
    The dish-shaped face of a Great Grey Owl. Photo © Cezary Korkosz
    An Owl uses these unique, sensitive ears to locate prey by listening for prey movements through ground cover such as leaves, foliage, or even snow. When a noise is heard, the Owl is able to tell its direction because of the minute time difference in which the sound is perceived in the left and right ear – for example, if the sound was to the left of the Owl, the left ear would hear it before the right ear. The Owl then turns it’s head so the sound arrives at both ears simultaneously – then it knows the prey is right in front of it. Owls can detect a left/right time difference of about 0.00003 seconds (30 millionths of a second!)

    An Owl can also tell if the sound is higher or lower by using the asymmetrical or uneven Ear openings. In a Barn Owl, the left ear left opening is higher than the right – so a sound coming from below the Owl’s line of sight will be louder in the right ear.

    The translation of left, right, up and down signals are combined instantly in the Owl’s brain, and create a mental image of the space where the sound source is located. Studies of Owl brains have revealed that the medulla (the area in the brain associated with hearing) is much more complex than in other birds. A Barn Owl’s medulla is estimated to have at least 95,000 neurons – three times as many as a Crow.

    Once the Owl has determined the direction of its next victim, it will fly toward it, keeping its head in line with the direction of the last sound the prey made. If the prey moves, the Owl is able to make corrections mid flight. When about 60 cm from the prey, the Owl will bring its feet forward and spread its talons in an oval pattern, and, just before striking, will thrust its legs out in front of its face and often close its eyes before the kill.

    • Extreme Hiatus says:

      Good summary. Tony’s photos are of a Great Horned Owl – not mentioned in this article – but Long-eared Owls have a similarly colored face (but are smaller and don’t sit on such open perches in the daytime).

      Worth noting that Great Horned Owls are, by far, the top owl predator and will hunt things as big as skunks or even house cats as well as other owls – although they usually hunt smaller prey (because there usually is more smaller prey). Although Great Gray Owls appear larger than Great Horned most of that size is thick feathers and they prey almost exclusively on little voles and other small rodents.

      Very nice photos again, particularly that owl!

      • Rud Istvan says:

        I was still hunting my farms deepest ravine near the flowing spring out in the far SE woodlot corner one fine fall day, and came across a great horned owl on a perch over the ravine. We had a good stare down at about 30 yards. Have no idea why it was so deep in the woods unless attracted to the spring water. The farms owls (barn and great horned), its red tail hawks, and its coyotes all have as their primary prey in that part of Wisconsin the abundant field mice and rabbits in the cattle pastures and adjacent forest edges, plus near any cattle feed areas to feast on leftovers. Used to have to stack horse feed sacks in a stand alone (away from shed walls) old galvanized water trough inside the tractor shed to minimize inevitable mouse damage.

  2. AndyG55 says:

    Luv these pictures……. did I mention I LUV owls !!!

    ——

    ps message for RAH.

    https://realclimatescience.com/2018/01/northern-sea-route-blocked-with-thick-ice/#comment-76754

  3. RAH says:

    Really enjoy these pics and everyone else should also because in my experience sightings of Great Horned owls are pretty rare. Far rarer than those of a Pileated Woodpecker.
    Spent a lot of time in various woods and wildernesses in the US and never once observed a Great Horned owl in the wild.

    When I was a kid I camped in about every state park that had camping available in Indiana. When camping at Versailles State park in Indiana the Nature Center there had a live Great Horned owl that had been injured and could not fly on display. But over the 50 years since that time I have never seen one in the wild. Count yourself lucky Tony.

    • Extreme Hiatus says:

      RAH, in open habitats like where Tony has been going it is (relatively) easy to see them because they simply have fewer places to hide, and that’s even more true at this time of year when the leaves are off the trees. But, as you suggest, in more forested areas they are very hard to find and, compared to most other owls, are a lot more wary and flush fast. That behavior is likely due to the fact that not so long ago people used to shoot them on sight because they can also prey on chickens and puppies and people were just more anti-predator in those days.

      That shooting explains why so many birds of prey were getting very rare. The DDT story is BS. The changing of laws and attitudes is why raptors have made a big comeback.

      • tonyheller says:

        I did a bike ride up the Potomac last June and saw two of them flying across the trail about one mile apart. I wasn’t able to get either of them in focus with the camera however.

  4. Disillusioned says:

    These are your VERY BEST photos yet. Thank you for sharing.

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