Author: Holly Strand

Holly is a Communications Specialist for the State of Utah’s Division of Emergency Management. A geographer by training, Holly received her master’s degree from the University of Colorado. She worked 10 years for World Wildlife Fund, helping collect expert knowledge to map and describe conservation priorities in biodiverse regions around the world. Before that, she led specialty tours to northern and eastern Eurasia. Over twenty years of professional work in great places with unique habitats and endemic species has given Holly an appreciation of what’s special within the Utah landscape.
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Why Do Birds Stand on One Leg?

Black-Necked Stilt
Himantopus mexicanus
Copyright © 2011 Holly Strand

Hi I’m Holly Strand.

On a recent Saturday my family and I visited Tracy Aviary in Salt Lake City. Walking through the wetland exhibit we saw a couple of black-necked stilts—a common Utah shorebird–snoozing near the boardwalk. They stood at the exhibit shoreline, each one balancing on a single, long, skinny, leg—the other leg drawn into the plumage underneath their bodies. Rotated almost 180 degrees, their heads and bills were tucked snugly under folded wings.

Why do birds choose to stand on just one leg? Wouldn’t it be more comfortable to distribute one’s weight on two? I’ve tried standing on one foot during yoga practice. It doesn’t feel like a good position for rest or sleep.

Over the years, several theories have emerged about this behavior in birds. One is that standing on one leg will reduce fatigue in the other leg. Then, if threatened, the bird could escape more quickly by using the rested leg to initiate motion.

Another theory is camouflage. Two parallel legs may look suspicious to ground level or aquatic prey. In contrast, one leg might resemble a reed or branch.

Perhaps the most common speculation is that birds are conserving heat via one-leggedness.

I wanted to test this last theory by standing barefoot in last weekend’s snow. First on one leg–and then on two for comparison. But I had a bad cold. I asked my biologist husband to do it for me, thinking he would be happy to support rational scientific thinking in the household. Alas, he rolled his eyes and made a noise that I’ve learned to translate as “You’ve got to be kidding me.”

Giving up on him, I dug deeper into the scientific literature.

At last I found a recent study conducted by Matthew Anderson and Sarah Williams of St. Joseph’s University. By observing Carribbean flamingoes these researchers showed that more birds stand on one foot at lower temperatures than at higher temperatures. Further, we know that loss of body heat to water is significantly greater than to air. So it would make sense to see more birds standing on one foot in the water than on land. And indeed this was the case. 80% of birds in water stood on one leg. On land, significantly less did so. Thus it does seem that temperature regulation is at least one reason for standing around on one leg.

In Utah look for one legged roosting among stilts, American avocets, night herons, double-breasted cormorants, and storks. Ducks, magpies and pigeons also stand on one foot for several minutes at a time
–it’s just harder to notice it in them because of their short legs.

For Wild About Utah, I’m Holly Strand.

Credits:

Table: Courtesy & Copyright © 2011 Holly Strand
Text: Holly Strand

Sources & Additional Reading:

Anderson, Mathew and Sarah A. Williams. 2010. Why do flamingos stand on one leg? Zoo Biology. Volume 29, Issue 3, pages 365–374, May/June 2010

Clark Jr., GA. 1973. Unipedal postures in birds. Bird-Banding, 44:22–26.

Tracy Aviary in Salt Lake City https://www.tracyaviary.org/

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A Big Year in Utah

Utah Big Year Records
Courtesy Utahbirds.org/records/

Hi I’m Holly Strand.

Birders are flocking to theaters to see the new movie The Big Year. The story is based on a real life competition among birders in which they race around to count the most birds within a particular geographic boundary in a single calendar year.

To do a Big Year, you need to follow some simple rules. To count a bird it must be alive and wild and unrestrained when encountered. You have to see enough or hear enough of the bird to absolutely be sure it’s the species you are claiming to see. And the bird must be within the prescribed area and time period of your particular Big Year competition. For instance if you are doing a Big Year for the state of Utah, you can’t count a bird that you see across the border in Idaho. However, you can be standing in Idaho looking at a bird in Utah, and you can count it.

To be competitive in a Big Year you have to find ALL the usual or common birds in your designated country, state or area. This means hitting all the major birdwatching spots at critical times during the year. In Utah you might want to start in the southwestern corner of the state picking up desert species such as vermillion flycatcher and greater roadrunner . Then head to the high Uintas to see Rocky Mountain alpine and subalpine birds such as the rosy finch and northern goshawk. You’d want to check out the Great Salt Lake in all four seasons and make frequent trips up and down the Wasatch canyons as different elevation zones harbor different species. Whenever possible you should be scouring wetlands and riparian zones for whoever might be perching, wading or fishing.

To push your count up beyond that of your competitors, you would need to spot rare birds, esp. vagrants. Vagrants are birds who have wandered or been blown off course. For example, when setting the Big Year record in Cache County, Ryan O’Donnell saw an Iceland Gull who was obviously terribly lost. And a Mexican Whip-poor-will that had somehow drifted up from Southern Arizona.

Modern communication technology is incredibly useful for locating rare birds and vagrants. Big Year participants monitor chat lists like Birdnet and BirdTalk run by Utahbirds.org. Ebird also helps spread the news of sightings. Email hotlines operate in several Utah regions. It always helps to maintain a network of birding friends who can text you the location of birds you haven’t seen yet.

Thanks to Frank Howe and Ryan O’Donnell of Utah State University’s Dept. of Wildland Resources for their assistance in developing this Wild About Utah story.

For Wild About Utah, I’m Holly Strand.

Credits:

Table: Courtesy utahbirds.org
Text: Holly Strand

Sources & Additional Reading:

American Bird Association https://www.aba.org/

Utah Birds https://utahbirds.org/

Ebird https://ebird.org/content/ebird/

Bridgerland Audubon Society Cache Birders Hotline https://www.bridgerlandaudubon.org/hotline.htm

Official movie site: https://www.thebigyearmovie.com/

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Crow vs. Raven

Common Raven (Corvus corax)
Bryce Canyon National Park
Courtesy US National Park Service
And found on Wikipedia

American Crow Juvenile & Parent
(Corvus brachythynchosby)
Copyright © 2011 Wayne Whaley

American Crow, Orem, UT
(Corvus brachythynchosby)
Copyright © 2011 Wayne Whaley

American Crow Pair, Orem, UT
(Corvus brachythynchosby)
Copyright © 2011 Wayne Whaley

Hi I’m Holly Strand.

As you might have guessed, the American crow and the common raven are birds of a feather—two closely related species of the same genus Corvus. Both of them are residents of Utah. Together with family members magpies and jays, crows and ravens are among the brainiest animals on the planet.

Many times I’ve heard someone ask “Is that a crow or a raven?” or “What’s the difference between them?”

Perhaps the easiest way to tell these two apart is by size. If you are thinking to yourself “Wow! That’s a huge crow!” You are probably looking at a raven. Ravens can weigh over 2.5 pounds while crows typically weigh less than 1. The Raven’s wingspan can clear 4.5 feet while that of crows is less than 3. Proportional to their bodies, the bill on a Raven is larger and thicker.
The crow has a thinner, more pointed bill.

Take a look at the tail in flight: a crow tail is fan shaped with a straight tail edge. A raven tail has a rounded wedge shape.

In the air, ravens usually soar, while crows will flap a lot more. It’s not always apparent why, but some ravens will perform acrobatic rolls during flight—usually half rolls, but sometimes full rolls and even double rolls!

Common ravens are abundant throughout Utah, They can be found in almost all habitats and in all seasons. They are more wilderness-oriented than crows who prefer forest edges, savannas, agricultural fields and urbanized areas. In cities and towns humans provide lots of easy food in the form of garbage. The crows’ intelligence allows them to take advantage of novel food items– like pizza and Cheetos–that don’t really resemble food in the wild.

Finally, listen to the difference in sound: Here are two crows calling—an adult and a juvenile https://xeno-canto.org/recording.php?XC=72977 . Now listen to the throatier sound of the raven https://www.xeno-canto.org/america/recording.php?XC=12581
Crows will also scream, rattle, whine and coo, but most of the time they just caw. Ravens have a richer, more complex vocabulary. They’ll scream, trill, knock, croak, cackle, warble, yell, and kaw. Young birds reared in isolation have even been taught to say “Nevermore.”

Thanks to Ryan O’Donnell and Andrew Spencer for their recordings available on the web at www.xeno-canto.org

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy US National Parks Service &
Courtesy & Copyright © 2011 Wayne Whaley
Text: Holly Strand

Sources & Additional Reading:

Boarman, William I. and Bernd Heinrich. 1999. Common Raven (Corvus corax), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: https://bna.birds.cornell.edu/bna/species/476

Kilham, Lawrence. 1989. The American crow and the common raven. W. L. Moody Jr. Natural History Series. College Station: Texas A&M University Press.

Marzluff, John M. 2005. In the company of crows and ravens. Yale University Press.

Savage, Candace Sherk , 1997. Bird brains: the intelligence of crows, ravens, magpies, and jays. Sierra Club Books.

Verbeek, N. A. and C. Caffrey. 2002. American Crow (Corvus brachyrhynchos), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: https://bna.birds.cornell.edu/bna/species/647

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Stromatolites

Stromatolites in Hamlin Pool
Shark Bay, Austalia
Courtesy Wayne A. Wurtsbaugh

Exposed stromatolites in the
Great Salt Lake
Courtesy
Utah Division of Wildlife Resources
Great Salt Lake Ecosystem Program

Stromatolites in Shark Bay
(Hamlin Pool) during low tide.
Courtesy Linda L’Ai

Hi I’m Holly Strand.

Shark Bay in Northwest Australia is on my “places to see before I die” list. In a section of the bay called Hamelin Pond, colonies of microbes form hard, dome-shaped, deposits. Called stromatolites, these structures embody one of the oldest forms of life on earth. The fossil record of microbes in older stromatolites date back 3.5 billion years. Their antiquity, abundance, and persistence to modern times make stromatolites a fascinating subject for scientific inquiry.

Basically, stromatolites are layered structures formed primarily by cyanobacteria. This photosynthesizing bacteria changes the pH of the water causing calcium carbonate to precipitate over a mat of bacterial filaments. The minerals, along with grains of sediment in the water, are trapped in a layer of goo that surrounds the bacterial colonies. Then the lower layer bacteria grows upward and penetrates the most recent mineral and sediment layer. When this process is repeated over and over, a stromatolite is formed.

For over 2 billion years stromatolites dominated the shallow seas and formed extensive reef tracts rivaling those of modern coral reefs. However, today, stromatolites are relatively rare. You will usually find them growing in extreme environments, such as hypersaline water or thermal springs.

While Shark Bay boasts a stunning example of a modern stromatolite colony, you don’t have to go all the way to Australia. When lake levels are low, you can easily see them in the Great Salt Lake. They span hundreds of square kilometers in shallow shoreline waters. Some say that the Great Salt Lake contains some of the most extensive areal coverage of living stromatolites in the world.

One of the best places to view them is from the shore near Buffalo Point on Antelope Island. When conditions are clear, you can see them underwater at the mouth of the Great Salt Lake Marina.

More than just memorials to ancient life, the stromatolites also play a vital role in Great Salt Lake ecology. They are the principal habitat for the brine fly larvae and pupae. In turn, brine flies are a critical diet for goldeneye ducks, American avocets and many other water birds.

Thanks to Wayne Wurtsbaugh, from Utah State University’s College of Natural Resources for his support in developing this Wild About Utah episode.

For Wild About Utah, I’m Holly Strand.

Credits:

Photos: Courtesy Utah Division of Wildlife Resources, Wayne A. Wurtsbaugh and Linda L’Ai
Text: Holly Strand

Sources & Additional Reading:

National Park Service. Stomatolite Fossils. https://www.nps.gov/care/naturescience/stromatolite.htm [Accessed August 16, 2011]

Schopf, J.William. Anatoliy B Kudryavtsev; Andrew D Czaja; Abhishek B Tripathi. 2007. Evidence of Archean life: Stromatolites and microfossils. Precambian Research, 158. No. 3-4 pp. 141-155.

UNESCO Shark Bay Western Australia https://whc.unesco.org/en/list/578 [Accessed August 16, 2011]

University of California Museum of Paleontology. Cyanobacteria: Fossil Record https://www.ucmp.berkeley.edu/bacteria/cyanofr.html [Accessed August 16, 2011]

Walter, M R. 1983. Archean stromatolites – Evidence of the earth’s earliest benthos
Earth’s earliest biosphere: Its origin and evolution. Princeton, NJ, Princeton University Press.

Wurtsbaugh, W.A. 2009. Biostromes, brine flies, birds and the bioaccumulation of selenium in Great Salt Lake, Utah. Pp. 1-15 In: A. Oren, D. Naftz, P. Palacios & W.A. Wurtsbaugh (eds). Saline Lakes Around the World:Unique Systems with Unique Values. Natural Resources and Environmental Issues, volume XV. S.J. and Jessie Quinney Natural Resources Research Library, Logan , Utah. URL: https://www.cnr.usu.edu/quinney/files/uploads/NREI2009online.pdf