Category: Vertebrates

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Hearts

Hearts abound this time of year – gracing cards, storefronts, and of course, chocolates. And while the heart symbol bears little resemblance to the organ itself, their abundance of late has caused me to consider my own heart, beating away largely unacknowledged all these years.

In its simplest form, the heart is a pump. Its sole function is to keep the blood in your body on the move, partnering with your lungs to deliver life-giving oxygen to each and every hard-working cell, from the top of your head to the tip of your pinky toe. Most hearts have two distinct features – an atrium where blood collects on its way into the heart and a ventricle which pumps the blood back out.

But even with these shared components, not all hearts are alike. Throughout the animal kingdom, hearts take on a variety of forms. Fish, for example, have a two-chambered heart: one atrium that collects blood and one ventricle that pumps it back out. Blood journeys from the heart to the gills, where it picks up oxygen and then continues on its way, delivering its cargo to the body before making its way back.

Amphibians and reptiles, with the exception of the crocodile, have a three-chambered heart consisting of two atria and one ventricle. One atrium is designated for the oxygen-poor blood that is headed towards the lungs while the other is reserved for oxygen-rich blood coming back from the lungs and headed out into the rest of the body. In the shared ventricle, blood from both atria mix slightly, resulting in a somewhat inefficient system that nonetheless seems to meet the needs of the animals it serves.

Mammals and birds have taken the heart one evolutionary step further with the development of a four chambered heart that fully separates oxygenated and deoxygenated blood. Blood flowing in from the lungs enters the left atria and is pumped out to the body by the left ventricle, while blood returning from the body enters the right atria and is pumped to the lungs via the right ventricle. Because of this total separation, the blood leaving a mammal’s heart contains more oxygen than a reptile’s – a huge metabolic advantage that helps support our warm-blooded fast-paced lifestyle.

Two-, three- and four-chambered hearts are considered closed circulatory systems, meaning the fluid, or blood, is fully enclosed within blood vessels. Insects, on the other hand, have an open circulatory system which means that they don’t have blood vessels at all. Instead their bodies are simply full of fluid that is continually circulated with the help of multiple simple hearts that pass liquid through as they contract and relax.

Lastly, there are some organisms that don’t need hearts at all! These creatures absorb oxygen through their skin and are small or thin enough that oxygen easily diffuses to all parts of the body. Some jellyfish, for example, have a body wall only two cells thick that separates their internal body space from the water around them.

Without our comparatively complex hearts, we probably wouldn’t be able to do what we do as humans and mammals. So take a moment during this Valentine’s season to acknowledge your amazing heart. Throughout the course of your lifetime it will beat upwards of 2 billion times and will pump as much as 100 million gallons of blood through its chambers. A pretty amazing feat for something we only celebrate once a year.

For the Stokes Nature Center and Wild About Utah, this is Andrea Liberatore.

Credits:
Text:     Andrea Liberatore, Stokes Nature Center in Logan Canyon.

Additional Reading:

Campbell, N.A. (1996) Biology, Fourth Edition. Benjamin/Cummings Publishing Company, Menlo Park CA

Bailey, Regina (2013) Circulatory System: Types of Circulatory Systems. https://biology.about.com/od/organsystems/a/circulatorysystem.htm

Meyer, J.R. (2005) Insect Physiology: Circulatory System. North Carolina State University. https://www.cals.ncsu.edu/course/ent425/tutorial/circulatory.html

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Desert Tortoises

Click for a larger view of an adult Desert Tortoise. Courtesy & Copyright 2009 Kevin Durso, Photographer
Adult Desert Tortoise
Gopherus agassizii
Courtesy & Copyright 2009
Kevin Durso, Photographer

Click for a larger view of an adult Desert Tortoise. Courtesy & Copyright 2009 Kevin Durso, PhotographerAdult Desert Tortoise
Gopherus agassizii
Courtesy & Copyright 2009
Kevin Durso, Photographer

Click for a larger view of an adult and juvenile Desert Tortoise. Courtesy & Copyright 2009 Andres Durso, PhotographerAdult & Juvenile Desert Tortoise
Gopherus agassizii
Courtesy & Copyright 2009
Andrew Durso, Photographer

Click for a larger view of a juvenile Desert Tortoise. Courtesy & Copyright 2009 Andres Durso, PhotographerJuvenile Desert Tortoise
Gopherus agassizii
Courtesy & Copyright 2009
Andrew Durso, Photographer

Tortoises are turtles that live their whole lives on land. Most tortoises are native to Africa and South America, but several are North American including the Desert Tortoise whose range extends to southwestern Utah. Their shells consist of enlarged scales called scutes. These scutes are tan, black, or dull orange, and etched with many concentric lines, like the growth rings of a tree. Desert Tortoises look like grizzled old men, even the Oreo-sized hatchlings, which over several decades will grow to football size.

Desert Tortoises mate in the spring, and a few months later, the female lays her 5 or 6 eggs in a funnel-shaped pit dug in the sand. The sex of the baby Desert Tortoises is determined by the sun’s heating rather than by genetics – cooler incubation yields males, hotter eggs produce females, with a mix of sexes developing at intermediate temperatures.

Desert Tortoises primarily eat the flowers of desert plants such as globemallow and threeawn. Because most desert plants only bloom briefly each spring, tortoises must eat a lot between April and June, although they can be active during all but the coldest months. Being toothless, they grind up their vegetarian fare using a specialized bone embedded in their jaw muscles. Like cows and other herbivores, they depend on microbes in their gut to digest the cellulose in their diet. Even more than food, water is precious to a Desert Tortoise. They have little to spare, sometimes going for months without urinating, but will pee defensively if handled. Resist the temptation to pick them up or you will rob the poor animal of its water supply for the entire year.

Once found throughout the Mojave and Sonoran deserts, Desert Tortoises are much less common than they were a century ago. They have not fared well with urbanization, highways, and off-road vehicle traffic. An upper respiratory tract disease can also be lethal, especially when crowded or stressed, as in captivity. Desert Tortoises are now protected by the US Endangered Species Act.

Today’s program was written by Andrew Durso of USU’s biology department.

Credits:

Theme: Courtesy & Copyright Don Anderson Leaping Lulu
Images: Courtesy & Copyright Andrew Durso and Kevin Durso
Text: Andrew Durso, https://www.biology.usu.edu/htm/our-people/graduate-students?memberID=6753

Additional Reading:

Gopherus agassizii, Turtle Conservancy, https://www.turtleconservancy.org/news/tag/Gopherus+agassizii

Grover, Mark C., DeFalco, Lesley A, Desert Tortoise(Gopherus agassizii): Status-of-Knowledge, Outline With References, USDA, 1995, https://www.fs.usda.gov/research/treesearch/30627

Desert Tortoise, Gopherus agassizii, Mojave National Preserve, https://www.mojavenp.org/Gopherus_agassizii.htm

Gopherus agassizii (COOPER, 1861), The Reptile Database, Peter Uetz and Jakob Hallermann, Zoological Museum Hamburg,
https://reptile-database.reptarium.cz/species?genus=Gopherus&species=agassizii

Desert Tortoise, Species, Utah Division of Wildlife Resources, Utah Department of Natural Resources, https://fieldguide.wildlife.utah.gov/?species=gopherus%20agassizii

Desert Tortoise Information and Collaboration, Mojave Desert Ecosystem Program, https://www.mojavedata.gov/deserttortoise_gov/index.html

Red Cliffs Desert Reserve, http://www.redcliffsdesertreserve.com

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Tracking Wildlife in Winter

Jumping Mouse Tracks
Photo Courtesy & Copyright 2011
Mark Larese-Casanova

Moose Tracks in Snow
Photo Courtesy & Copyright 2011
Mark Larese-Casanova

Cottontail Rabbit Browse & Scat
Photo Courtesy & Copyright 2011
Mark Larese-Casanova

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

The cold depth of winter is a time when many animals are hiding- either hibernating until the thaw of spring, or finding shelter and warmth in burrows, under logs, or in the tangled branches of evergreen trees.

However, snow falls in much of Utah, and even a dusting can reveal the stories of wildlife in winter. It’s a bit like solving a mystery. By reading the clues of animal tracks, we can know not only the type of animal that made them, but also where they were going and what they were doing.

The most obvious clue is the size of a track. Smaller animals make smaller tracks, and also sets of tracks that are generally closer together.

The shape of an animal track is also very revealing. Members of the canine family, including domestic dogs, coyotes, and fox, show four toes in front, each with a visible claw. Felines, including bobcats and mountain lions, also show four toes, but no claws. Tracks from members of the weasel family, such as mink, ermine, and skunks, show five toes, each with a claw. Raccoon, squirrel, and mouse tracks almost look like they were made by tiny human hands. The long tails of some animals, including deer mice, jumping mice, and weasels, often leave a characteristic line through the center of a set of tracks.

Combining the size and shape of tracks reveals further details about wildlife. The three inch long cloven hoof print of a mule deer is easily recognizable. An elk track looks almost identical, but is about four inches long. A similar moose track is even larger at six inches long.

Figuring out which animal made a track is only half of the story. If we follow tracks, we’ll surely find clues about an animal’s daily life. Wildlife often gather around sources of water that aren’t frozen, which are critical to winter survival. Perhaps rabbit tracks lead under a spruce tree where browsed branches and droppings indicate a frequent feeding spot. Maybe mouse tracks lead from tree to rock to log as it avoids owls and hawks.

While we are much more likely to see wildlife during the warmer months, winter gives us a chance to unravel the story of daily survival during the most difficult time of the year in Utah.

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

Credits:
Images: Courtesy and Copyright Mark Larese-Casanova
Text:     Mark Larese-Casanova

Additional Reading:

Canadian Wildlife Federation: Tracking Down Winter Wildlife. https://www.cwf-fcf.org/en/action/how-to/outside/tracking-down-winter-wildlife.html

Murie, O. J. (1982). Animal Tracks. Peterson Field Guides. New York, NY: Houghton Mifflin. https://www.amazon.com/Peterson-Field-Guide-Animal-Tracks/dp/061851743X

Vermont Nature and Outdoors: Tracking Winter Wildlife. https://www.ruralvermont.com/vermontweathervane/issues/winter/97012/vins97012_tracking.shtml

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Winter Song Birds

A Black-capped Chickadee, Bridgerland Audubon Society

A Black-capped Chickadee
Bridgerland Audubon Society

In the icy, short days of winter, you may think that Nature itself has curled up to hibernate. Our gardens are drab and deciduous trees are stripped down to bare limbs and twigs. Many songbirds have bid us farewell and flown south. In truth, what remains to be seen and heard of nature here in winter is more subtle and less boisterous. Now is the time to learn calls and songs of birds that reside here year-round, to hear them in solo performances, before the confusing springtime symphonies of birdsong.

This first bird calls its own name [sound: “Chick-a-dee-dee-dee” #9 Songbirds of the Rocky Mountain Foothills]. Black-capped Chickadees take sunflower seeds one at a time from our feeders. When out snowshoeing or skiing in our forests, inquisitive chickadees are welcome companions. They bring joy to a wintry day.

Frequently, a winter chickadee flock includes other birds. [Sound: “annk-annk” #48 Songbirds of Yellowstone] This bird sounds like a child’s squeak toy, but that nasal call belongs to the Red-breasted Nuthatch. Look for this chunky small bird at your suet feeder, or cruising up and down tree trunks in its search for insects.

We also have a minimalist in our winter bird repertoire [Sound: “tew” #62 Songbirds of Yellowstone]. That single note belongs to the Townsend’s Solitaire, which looks like a lean robin, colored the somber gray of an overcast sky. In winter, solitaires dine predominately on juniper berries. Their call stakes out their winter feeding territory. They are regulars at our heated birdbath, perhaps washing down all those puckery berries. If you are lucky, you may also hear their musical warbling, which is more common in warmer months. (Kevin Colver: Songbirds of Yellowstone)

You often hear chickadees, nuthatches and solitaires before you see them, as their plumage is neither colorful nor splashy. If you notice these calls on a winter’s day, it is because you are quiet and focused on the nature around you, leaving civilization’s hubbub behind. Thank-you to Kevin Colver for his wonderful bird recordings.

Credits:

Bird Sounds: Courtesy and Copyright 2008 Dr. Kevin Colver, Songbirds of the Rocky Mountain Foothills and Songbirds of Yellowstone and the High Rockies https://wildstore.wildsanctuary.com/collections/special-collections

Text: Jim Cane, Bridgerland Audubon Society https://www.bridgerlandaudubon.org

Additional Reading:

Black-capped Chickadee, All About Birds, Cornell Lab of Ornithology, https://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Black-capped_Chickadee.html

Red-breasted Nuthatch, All About Birds, Cornell Lab of Ornithology, https://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Red-breasted_Nuthatch.html

Townsend’s Solitaire, All About Birds, Cornell Lab of Ornithology, https://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Townsends_Solitaire.html