Wildlife dispersal in late summer (Or, It’s time to leave the nest!)

Wildlife dispersal in late summer: Click to view larger image of Adult great-horned owl perched at dusk, hunting for its young, Photo Courtesy and Copyright Mark Larese-Casanova
Adult great-horned owl
perched at dusk,
hunting for its young
Photo Courtesy & Copyright 2009
Mark Larese-Casanova

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Late summer is the time of change when the rich nature born of spring matures and enters the next stage of its life. Streams and wetlands may dry up in the heat. Wildflowers wither and produce seeds to ensure a plant’s survival into the future. And, young wildlife leave their place of birth to strike out on their own.

Prior to fledging, young red-tailed hawks build flight muscles by hopping and flapping their wings in the nest. Once they are strong enough, the young red-tailed hawks make excursions from the nest, often soaring together, calling to each other while they fly. This time of year, red-tailed hawk fledglings can still be seen perched atop telephone poles, even in the middle of town, calling to their parents and begging for food. As a bird that usually spends the entire year in Utah, the red-tailed hawk must prepare for its solitary, cold winter ahead.

The calls of great horned owls often echo through the late summer nights. The adult owl soars through an open field while the fledgling owlet is perched nearby, calling for food. The parent responds, and faithfully catches a mouse to feeds its young. Aside from their echoing calls, this all happens quietly and almost invisibly. A lucky observer might spy an owlet and its parent at dusk, but the great horned owl’s soft feathers ensure that their flight is silent, even when just overhead.

Some young reptiles disperse in summer, too, just like birds. Tiny garter snakes, no larger in length or width than a pencil, can often be found slithering across meadows or even lawns. Rather than laying eggs in a nest, the female garter snake retains the eggs in her body until they are ready to hatch. While young garter snakes receive no parental care after birth, the mother hedges her bets by producing upwards of twenty young in the second half of each summer. At least two need to survive over the mother’s life to maintain a stable population.

Fledging and dispersal in late summer is a time of great risk, though. It’s very common in Utah to see road kill of young marmots, skunks, raccoons, and mink, among others. Many inexperienced young animals are also taken by predators. In nature, survival to adulthood is relatively uncommon, so the great investment of the parents is essential for a species to survive.

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:

Images: Courtesy and copyright Mark Larese-Casanova
Text:     Mark Larese-Casanova, Utah Master Naturalist Program at Utah State University Extension.
Additional Reading:

Danilson, C.D. Post-Fledging Ecology of Great Horned Owls in South Central Saskatchewan. Master’s Thesis. http://scholarworks.boisestate.edu/td/505/

Great Horned Owls. All About Birds. Cornell Lab of Ornithology. http://www.birds.cornell.edu/AllAboutBirds/owlp/ghowl

Red-tailed hawk. Hawkwatch International. http://www.hawkwatch.org/blog/item/130-red-tailed-hawk-buteo-jamaicensis

Red-tailed hawk. Utah Conservation Data Center. http://dwrcdc.nr.utah.gov/rsgis2/search/Display.asp?FlNm=butejama

Terrestrial gartersnake. Utah Conservation Data Center. http://dwrcdc.nr.utah.gov/rsgis2/Search/Display.asp?FlNm=thameleg

Thamnophis elegans: Western Terrestrial Garter Snake. Animal Diversity Web. http://animaldiversity.ummz.umich.edu/accounts/Thamnophis_elegans/

Owls & iPods

Owls & iPods: Great Horned Owl and Chick, Courtesy US FWS Digital Library, George Gentry Photographer
Great Horned Owl and Chick
Photographer: George Gentry
US FWS Digital Library

Hi I’m Holly Strand.

In early spring, my friends and I went owling in a northern Utah canyon. We were hoping for modest success—just to see or hear a northern pygmy or great horned owl — both common owls in our area.

To better the odds we brought an iPod with prerecorded owl sounds. We played the northern pygmy call for 20-30 second intervals and listened intently in between intervals.

After 10 minutes of off-and-on playbacks we heard an answering call from a nearby conifer grove. We were ecstatic that we had made contact with an actual owl. But wait! Was it an owl we heard or just another iPod user?

Pygmy Owl, Courtesy US FWS Digital Library, Bob Miles Photographer
Pygmy Owl
Photographer: Bob Miles
US FWS Digital Library

According to David Sibley, author of the Sibley Guide to Birds, the proliferation of digital audio devices and recorders among birders has both pluses and minuses. On the plus side, you can often entice certain birds out of hiding using playbacks. For example, if a territorial male thinks a rival bird is threatening to encroach on its territory, he may come out to confront the intruder. Or he may sing his “I’m Here, So Stay Away” song. A female bird might approach the recording source as a potential date. Using playbacks, you can target specific species to see or hear without disturbing others.

On the flip side, overuse of these playback devices can cause unnecessary stress and distraction in the target birds—and annoyance among other birders. In one study, the use of playbacks upset the avian apple cart by causing high-ranking black- capped chickadee males to lose status. The rest of the flock perceived them as losers as they were unable to drive away an unwanted phantom intruder.

Because the widespread use of recorded playbacks is relatively new, proper etiquette is still evolving. But here are some key points.

  • Keep the volume low and use only occasional snippets of sound—less than 30 seconds at a time. Leave a long pause between snippets. Definitely do not broadcast loud or continuous sound.
  • It is illegal to disturb endangered or threatened species. And these recordings can be interpreted as disturbance. So stick with sounds of non-threatened species.
  • Finally, check the rules at your birding location. The use of playback is prohibited in some parks and refuges.

For source material and websites with bird sound recordings, go to www.wildaboututah.org.

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy US FSW Digital Media Library
Text: Holly Strand

Sources & Additional Reading:

Sibley, David. 2011. The Proper Use of Playback in Birding. Sibley Guides: Identification of North American birds and trees. http://www.sibleyguides.com/2011/04/the-proper-use-of-playback-in-birding/ [Accessed May 19, 2011]

Recordings:

Soundscapes for Birders by Kevin Colver http://www.7loons.com/

http://www.xeno-canto.org/ shared bird sounds from the whole world

Beletsky, Les, editor. 2010. Bird Songs Bible: The Complete, Illustrated Reference for North American Birds Contains digital audio player.

Ipods and mp3 apps:

iBird http://www.ibirdexplorer.com

Audubon Birds Field Guide http://www.audubonguides.com/field-guides/mobile-apps.html

The Sibley eGuide to the Birds of North America http://www.mydigitalearth.com

Owls: Silent Hunters

Barn owl sleeping in a tree, Photo Copyright 2010 Mike Fish
Barn Owl Sleeping in a Tree
Copyright © 2010 Mike Fish

Great Horned Owl  Photographer: Ronald Laubenstein US FWS Digital Library Great Horned Owl
Photographer: Ronald Laubenstein
US FWS Digital Library

Click for a larger image - Western Screech Owl courtesy and copyright 2007 Lu Giddings Western Screech Owl
Copyright © 2007 Lu Giddings

Click for a larger view of the tethered Snowy Owl, Bubo scandiacus, Image courtesy US FWS.  Ronald Laubenstein, Photographer Tethered Snowy Owl in Alaska
Bubo scandiacus

Courtesy US FWS
Ronald Laubenstein, Photographer

Click for a larger view of Snowy Owl in Alaska, Bubo scandiacus, Photo taken in Alaska by Floyd Davidson, Photographer, Courtesy Wikimedia and licensed through GNU Free Documentation License 1.2Snowy Owl in Alaska
Bubo scandiacus

Courtesy Wikimedia
Floyd Davidson, Photographer
Licensed under the
Creative Commons: GNU Free Documentation License

Click for a larger view of Snowy Owl with chick, Bubo scandiacus, Photo taken by Tony Hisgett, Photographer, Courtesy Wikimedia and licensed through the Creative Commons: Attribution 2.0 Generic LicenseSnowy Owl with Chick
Bubo scandiacus

Courtesy Wikimedia
Tony Hisgett, Photographer
Licensed under the
Creative Commons: Attribution 2.0 Generic License

Click for a larger view of Snowy Owl in Alaska, Bubo scandiacus, Photo taken by Bert de Tilly, Photographer, Courtesy Wikimedia and licensed through the Creative Commons: Attribution-Share Alike 3.0 Unported LicenseSnowy Owl in Flight
Bubo scandiacus

Courtesy Wikimedia
Bert de Tilly, Photographer
Licensed under the
Creative Commons: Attribution-Share Alike 3.0 Unported License

Hi, this is Mark Larese-Casanova from the Utah Master Naturalist Program at Utah State University Extension.

Walking across the yard late at night, the crescent moon was casting little light. A dark, phantom shape soared past our heads. It was silent, not making a single noise. It could only be one thing out here in the night- an owl, drifting off into the darkness.

Even though they hunt at night, owls use their vision to find prey. Owl eyes are proportionately large compared to those of other birds, and also have large corneas and pupils to allow more light into the eye. The retina, where an image is formed at the back of the eye, is so large that an owl’s eye is shaped more like a rounded cone or tube rather than a ball. Because the back of an owl’s eye is wider than the front, owls cannot move their eyes within the socket like other animals. To make up for this, owls are able to turn their heads three-quarters of a full rotation!

To supplement its acute vision, owl’s ears are particularly well adapted for hearing prey. In fact, some owls hear so well that they can catch prey in complete darkness. The feathers of the facial disk- the round, flat areas around the eyes- help direct sound toward their large ear openings. In addition, an owl’s ear openings are set relatively far apart on its skull, and at different orientations on each side. One is high and more forward on the skull, and the other is lower and to the rear. This allows owls to locate noises, such as the rustling of a mouse, by triangulation with remarkable precision.

Excellent sight and hearing are helpful to owls, but very quiet feathers help them sneak up on prey. Relatively large wings covered with feathers that have a velvety soft upper surface and a serrated edge reduce noise during flight. Owls even have feathers on their legs to help keep quiet!

Most birds sleep soundly in their roosts at night. But, it’s not uncommon for us to see an owl gliding through the darkness in search of its prey. Just don’t expect to hear them…

For Wild About Utah, I’m Mark Larese-Casanova.

Credits:
Images: Courtesy US FWS images.fws.gov
Courtesy and Copyright Mike Fish
Courtesy and Copyright Lu Giddings
Courtesy Wikimedia & licensed through CCL
Text:     Mark Larese-Casanova, Utah Master Naturalist Program
            at Utah State University Extension.


Additional Reading:

Berger, C. (2005). Owls. Mechanicsburg, PA: Stackpole Books.

Lynch, W. (2007). Owls of the United States and Canada. Baltimore, MD: Johns Hopkins University Press.

Owl Feathers and Flight. (2012). In The Owl Pages. Retrieved September 20, 2013, from http://www.owlpages.com/articles.php?section=owl+physiology&title=Feathers

Owl Eyes and Vision. (2012). In The Owl Pages. Retrieved September 20, 2013, from http://www.owlpages.com/articles.php?section=owl+physiology&title=Vision

Owls and iPods

Great Horned Owl and Chick, Courtesy US FWS Digital Library, George Gentry Photographer
Great Horned Owl and Chick
Photographer: George Gentry
US FWS Digital Library

Hi I’m Holly Strand.

In early spring, my friends and I went owling in a northern Utah canyon. We were hoping for modest success—just to see or hear a northern pygmy or great horned owl — both common owls in our area.

To better the odds we brought an iPod with prerecorded owl sounds. We played the northern pygmy call for 20-30 second intervals and listened intently in between intervals.

After 10 minutes of off-and-on playbacks we heard an answering call from a nearby conifer grove. We were ecstatic that we had made contact with an actual owl. But wait! Was it an owl we heard or just another iPod user?

Pygmy Owl, Courtesy US FWS Digital Library, Bob Miles Photographer
Pygmy Owl
Photographer: Bob Miles
US FWS Digital Library

According to David Sibley, author of the Sibley Guide to Birds, the proliferation of digital audio devices and recorders among birders has both pluses and minuses. On the plus side, you can often entice certain birds out of hiding using playbacks. For example, if a territorial male thinks a rival bird is threatening to encroach on its territory, he may come out to confront the intruder. Or he may sing his “I’m Here, So Stay Away” song. A female bird might approach the recording source as a potential date. Using playbacks, you can target specific species to see or hear without disturbing others.

On the flip side, overuse of these playback devices can cause unnecessary stress and distraction in the target birds—and annoyance among other birders. In one study, the use of playbacks upset the avian apple cart by causing high-ranking black- capped chickadee males to lose status. The rest of the flock perceived them as losers as they were unable to drive away an unwanted phantom intruder.

Because the widespread use of recorded playbacks is relatively new, proper etiquette is still evolving. But here are some key points.

  • Keep the volume low and use only occasional snippets of sound—less than 30 seconds at a time. Leave a long pause between snippets. Definitely do not broadcast loud or continuous sound.
  • It is illegal to disturb endangered or threatened species. And these recordings can be interpreted as disturbance. So stick with sounds of non-threatened species.
  • Finally, check the rules at your birding location. The use of playback is prohibited in some parks and refuges.

For source material and websites with bird sound recordings, go to www.wildaboututah.org.

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy US FSW Digital Media Library
Text: Holly Strand

Sources & Additional Reading:

Sibley, David. 2011. The Proper Use of Playback in Birding. Sibley Guides: Identification of North American birds and trees. http://www.sibleyguides.com/2011/04/the-proper-use-of-playback-in-birding/ [Accessed May 19, 2011]

Recordings:

Soundscapes for Birders by Kevin Colver http://www.7loons.com/

http://www.xeno-canto.org/ shared bird sounds from the whole world

Beletsky, Les, editor. 2010. Bird Songs Bible: The Complete, Illustrated Reference for North American Birds Contains digital audio player.

Ipods and mp3 apps:

iBird http://www.ibirdexplorer.com

Audubon Birds Field Guide http://www.audubonguides.com/field-guides/mobile-apps.html

The Sibley eGuide to the Birds of North America http://www.mydigitalearth.com