Cicadas: What is up with that sound?

Around this time of the year, the woods of River Legacy start producing a very peculiar sound. It is loud and generally described as a high-pitched buzzing sound. The origin of this sound is one of the most intriguing and well-known inhabitants of River Legacy: the cicada. It is quite likely that you have heard this sound before. It forms an integral part of the summer experience in North America. Let’s delve more into cicadas and the sound they produce.

Cicadas are insects that belong to the order Hemiptera, a very big and diverse order of insects known collectively as the “true bugs and relatives.” This makes cicadas distant relatives to insects such as aphids, stink bugs, shield bugs, leafhoppers, and bed bugs–yes, those bed bugs! There are roughly 3,000 species of cicadas and they inhabit every continent except Antarctica. In North America, there are about 200 species of cicadas. The most common species of cicadas belong to the genera Tibicen, Megatibicen, Hadoa, and Diceroprocta and are known as the dog-day cicadas. These are considered to be annual cicadas.

This means that they have a life cycle that lasts anywhere from 2 to 5 years, in general. On the other hand, species belonging to the genus Magicicada are known as the periodic cicadas, because their life cycle is very different from the others. These cicadas have either a 13-year or 17-year life cycle, so broods can remain underground for years until it is time for them to emerge. The vast majority of these cicadas can be found east of the Mississippi River. Most of the cicadas in Texas are annual cicadas though there are some members of Magicicada found in counties along the Red River, bordering Oklahoma.

The cicada sound is essentially a mating call produced by the males in order to attract a female cicada. The sound can also be used to announce an individual’s territory. The origin of this sound can be traced back to a special organ that few insects have: the tymbal organ. The male cicadas possess 2 of these, which are circle-shaped ridged membranes found on the back and side of the 1st abdominal segment of the cicada. The muscle that attaches to the tymbals contracts and bends the tymbals, which creates a clicking sound. When the muscle relaxes, they go back to their previous form. The tymbals contract so frequently (120 to 480 times a second) that it appears as a long, continuous sound to the human ear. There are air sacs in Cicadas that amplify the sound to produce the iconic cicada buzzing sound!

Cicadas are very special insects with an amazing adaptation that has made them world famous. As you take a walk through the River Legacy this summer, remember how the cicada sounds are being made as they graciously cover the woods.

Sources:

  • Bauer, Patricia. “Why are cicadas so noisy?”. Encyclopedia Britannica, Invalid Date, https://www.britannica.com/story/why-are-cicadas-so-noisy. Accessed 9 May 2022.
  • Evans, Arthur. Field Guide to Insects and Spiders of North America. 1st ed., New York, Sterling Publishing Company, 2008.
  • Abbott, John, and Kendra Abbott. Common Insects of Texas and Surrounding States: A Field Guide. 1st ed., Austin, University of Texas Press, 2020.
  • Drees, Bastiaan, and John Jackman. A Field Guide to Common Texas Insects. 1st ed., Houston, Gulf Publishing Company, 1998.
  • Liebhold, A. M., Bohne, M. J., and R. L. Lilja. 2013. Active Periodical Cicada Broods of the United States. USDA Forest Service Northern Research Station, Northeastern Area State and Private Forestry.

How come there are no blue or green mammals?

Have you ever thought about this? Think about it for a minute. If you were to list 10 mammals off the top of your head – perhaps animals like your dog, cat, an elephant, rat, zebra, skunk, raccoon, opossum, bobcat, or even a coyote – you would quickly realize that the colors of these mammals lack blue and green hues. There are a couple of reasons as to why this is, and why other animals like insects, birds, amphibians, and reptiles exhibit these colors quite often.

The reason has to do with chemistry primarily. First off, let’s talk about what produces colors in living things. Pigments are chemical compounds that are responsible for producing color in the biological world. When pigments absorb light, they reflect back certain wavelengths, producing colors our eyes can perceive. Plants, for example, have many different kinds of pigments with all kinds of peculiar names, such as carotenoids, flavonoids, and anthocyanins. Thousands of these chemicals have been identified by scientists and this is the reason why plants can produce a vast array of colors – from the dominant green leaves, to different shades of bark on trees, to the orange color of a carrot, the colorful fruits and flowers there are and the beautiful foliage colors we see during autumn in temperate latitudes.

When it comes to animals however, things are a bit different. The vast majority of animals simply do not have the variety of pigments that plants do. Specifically, they are not able to genetically produce blue and green pigments. Then how come we still see animals that are those colors? There’s blue butterflies, green frogs, and peacocks are well-known for their blue feathers! Most of these animals produce this color through a phenomenon known as structural coloration, which is the optical illusion of a color, essentially. Small structures of the skin scatter and reflect back light in a way so that only the blue wavelengths reach our eyes. But, in reality, there is no blue pigment doing that. When it comes to green, usually there is a yellow pigment involved with a structural blue coloration.

For instance, when a rough green snake (Opheodrys aestivus), a common River Legacy snake, dies, it turns blue because the yellow pigment is no longer being produced but the structural color is still there. Another way animals are able to produce vibrant colors is by obtaining pigments from their environment, typically their diet. This is how flamingos develop their typical pink to red hue, by eating foods like algae, shrimp, and crabs that have these pigments in them. A similar phenomenon occurs with the northern cardinal (Cardinalis cardinalis), another River Legacy common sight.

Now, let’s go back to mammals. Mammals have not been able to evolve or have lost the ability to implement pigments obtained through their diet to the same extent as other animals have. It happens but not to the same degree. This is why eating something like beets can turn the toilet a certain color when we go to the bathroom but it does not turn our skin purple. When it comes to naturally-produced pigments, mammals really only produce one kind – melanin. Melanin is an important pigment that provides protection against the sun’s damaging UV rays but it also is responsible for the majority of colors in mammalian skin. It comes in two kinds – eumelanin (responsible for black and brown colors) and pheomelanin (responsible for yellow or reddish to brown colors). Very few mammals, like mandrills (a type of African monkey), are able to produce small amounts of blue color through structural coloration.

But, how come no other mammals can? Scientists are not really sure but it may have had to do with the evolutionary history of mammals. Early mammals survived during the Mesozoic era, the golden age of the dinosaurs, by basically not being around them too much in order to avoid becoming food or by not trying to compete with them for the same resources. It is believed that most dinosaurs were active during the day so it is most likely that mammals had to turn to a largely nocturnal lifestyle. This meant that mammals did not have the need to develop adaptations that were not necessary in the night, such as the ability to see a wide range of vibrant colors. If there was no selective pressure (i.e. need) for either evolving structural coloration, pigment formation, or the ability to obtain pigments through diet, then the genes that allowed for those traits disappeared from the mammalian gene pool. The majority of animals today, with the exception of most mammals, have stellar color vision. On the other hand, as a result of their evolutionary history, mammals tend to be color-blind when it comes to blue and green colors. The big exception to this are primates – the group to which humans and mandrills belong. Therefore, it is hypothesized that as a result of all of this, the vast majority of mammals lack green or blue colors on their skin or fur.

What an incredible and fascinating subject to be sure. Next time you take a hike in the River Legacy trails and you come across a mammal – whether it be a squirrel, bobcat, or rabbit – you will know why those creatures are not flashing blue and green at you!

Dinosaurs Did Not All Go Extinct. They’re Still Around and They’re Everywhere!

Have we been duped about dinosaur extinction? Well, it turns out that we pretty much have been. Since the very first time that paleontologists have found dinosaur fossils, people have known about the existence of these prehistoric, mesmerizing, and typically large creatures. Dinosaurs dominated the biosphere of our planet during what is called the Mesozoic Era, which spanned from roughly 250 million years ago to 66 million years ago. Dinosaurs especially thrived during the Jurassic (201 million years ago to about 145 million years ago) and Cretaceous (145 million years ago to about 65 million years ago) periods of this era until they all went extinct at the end of the Cretaceous, about 65 millions years ago, very likely due to an asteroid impact. With this tragedy, the impressive reign of the once mighty dinosaurs came to a close. Or, so we thought…

The fossil of Archaeopteryx, a feathered dinosaur from the Jurassic where the wings can be clearly seen.
Northern cardinal, a modern-day River Legacy dinosaur.

However, it turns out that not all dinosaurs went extinct! Around 150 millions years ago, during the Jurassic period, a group of small, feathered theropod dinosaurs (dinosaurs that are characterized by hollow bones and three toes and includes famous dinosaurs such as members of the genera Tyrannosaurus, Carnotaurus, Spinosaurus, and Velociraptor) evolved into a group of animals we are very much familiar with, the birds. That is exactly right. Your backyard northern cardinal, the woodpecker you saw on your last hike through River Legacy, and your pet parakeet are all very distant cousins of the T-Rex and raptors from those ancient times! The similarities between these enigmatic animals of the past and our feathered friends abound. For instance, the presence of feathers, a key feature of birds, in dinosaurs such as members of the genus Archaeopteryx has been long documented. Research has also shown similarities between dinosaur and bird skeletons, particularly in the neck, pelvic, and pectoral areas. Behavioral similarities between birds and dinosaurs have been documented as well, ranging from brooding and caring for offspring, to similar sleeping posture, to the ingestion of gizzard stones which are stones that aid in digestion in birds and other animals. In 2008, another proof of the link between dinosaurs and birds emerged: the discovery pointing to the presence of air sacs, another key characteristic of birds, in the genus Aerosteon, a theropod dinosaur from Argentina.

Southern cassowary, a modern-day Australian dinosaur, that is more reminiscent of a Velociraptor.
Tyrannosaurus
Velociraptor

Even as the mighty dinosaurs took their last breath in the aftermath of the late Cretaceous impact event, a small but persistent group of theropod dinosaurs managed to escape catastrophe, survived the extinction event, and eventually flourished and evolved into an amazing diversity of roughly 10,000 bird species found today, from the wild turkey to the turkey vulture, from the hummingbird to the ostrich, from the blue jay to the mallard duck.


Do you and your family want to experience more of the world of dinosaurs, birds’ long-extinct distant cousins? River Legacy Nature Center is excited to present Dinosaur Safari, a traveling exhibit that is open NOW and will run through February 12th, 2022. Come immerse yourself back in the Mesozoic as you learn more about our prehistoric past and experience life-sized dinosaur models, while children get hands-on experience in investigating the clues these animals left behind. Click here to learn more about this limited time exhibit.

Dinosaur Safari is created by Omaha Children’s Museum.

Autumn is Here and So Are the Birds!

Autumn is in full swing at River Legacy and life in the forest is experiencing some changes. We have covered in previous posts what some of those are. Today, we will primarily focus on the fall bird migration and the species you can enjoy seeing!

Autumn migration typically starts in late summer, around the middle to end of the month of August. The reason why many species migrate during this time is their need to find suitable temperatures and food sources in order to survive. North America is slowly entering the coldest part of the year and many species would not do well in that type of condition. Food becomes scarce so birds are forced to go back to warmer, more rich places in the southernmost parts of the U.S. (including northern Texas), Mexico, Central America, or even South America. River Legacy is fortunate to be located right in the middle of the Central Flyway, a migratory route that spans a wide swath of the central United States, Canada, and Mexico.

So what are some of the species that people can start to see this autumn and are expected to stay through the remainder of autumn and winter?

Several waterfowl are included in this group. Species such as the Canada goose (Branta canadensis), wood duck (Aix sponsa), blue-winged teal (Anas discors), and northern shoveler (Spatula clypeata) are fairly common sights.

Another group with several autumn and winter representatives are the sparrows. Some of those are the white-throated sparrow (Zonotrichia albicollis), the white-crowned sparrow (Zonotrichia leucophrys), the eastern towhee (Pipilo erythrophthalmus), and the dark-eyed junco (Junco hyemalis), among many.

Some woodpeckers, birds of prey, and other song birds also start to appear this time of year. These include, but are not in any way limited to, the yellow-bellied sapsucker (Sphyrapicus varius), the red-headed woodpecker (Melanerpes erythrocephalus), the northern flicker (Colaptes auratus), the ruby-crowned kinglet (Regulus calendula), the cedar waxwing (Bombycilla cedrorum), the brown thrasher (Toxostoma rufum), and the sharp-shinned hawk (Accipiter striatus).

Lastly, in addition to these birds moving in, you can still enjoy some of the birds that live at River Legacy all year-round. Among the common year-round species that live here are the northern cardinal (Cardinalis cardinalis), the northern mockingbird (Mimus polyglottos), the red-winged blackbird (Agelaius phoeniceus), the red-shouldered hawk (Buteo lineatus), the barred owl (Strix varia), the great horned owl (Bubo virginianus), the Bewick’s wren (Thryomanes bewickii), the eastern phoebe (Sayornis phoebe), the downy woodpecker (Dryobates pubescens), the red-bellied woodpecker (Melanerpes carolinus), the mallard (Anas platyrhynchos), and the Carolina chickadee (Poecile carolinensis).

Have you had some exciting bird sightings around River Legacy Park? Snap a picture and show us what you’ve seen by tagging us on Facebook @riverlegacyparks or on Instagram @livingsciencecenter!

Cedar waxwing (Bombycilla cedrorum)
Eastern towhee (Pipilo erythrophthalmus)
Blue-winged teal (Anas discors)

Great Backyard Bird Count

Do you have 15 minutes to spare? If you answered yes you can help scientists collect data on the distribution and abundance of birds through the Great Backyard Bird Count (GBBC). The GBBC started in 1998 by Cornell Lab of Ornithology and National Audubon Society. This year (2020) the GBBC is February 14-17. Participants can count from any location around the world and for any amount of time no less than 15 minutes. All you need to do is create a tally of the different birds observed. Not to worry if you’re not an expert birder; all levels are welcome! 

Bird populations are forever changing, which makes it important for scientists to track their numbers. This is a huge and difficult task for a handful of people to conquer. That is why scientists need the help of citizens to collect information. The data collected from the GBBC can help scientists understand if certain bird species are increasing or decreasing over time. Any big changes are indicators of environmental changes that are affecting the birds. GBBC information also provides a snapshot of the different kinds of birds that live in different areas. In 2019, GBBC participants from 100 countries helped to count over 6,800 species on more than 200,000 checklists.

If you’re interested in participating and need more information on how to create an account and how to submit observations visit the link here: https://gbbc.birdcount.org/get-started/ 

River Legacy will be holding a GBBC festival on February 15th from 10 am – 2 pm. Come join us for guided family bird walks/group counts, live animal presentations and plenty of owl-some crafts and activities! We will also have some im-peck-able exhibitors such as Fort Worth Audubon Society, U.S. Fish and Wildlife and Fal-Tech Inc. with live birds! Come and fla-mingle with us. We hoot to see you there!

Shedding Snakes

Most animals (including humans!) shed their skin. As humans, we usually shed our skin in small pieces and we hardly ever notice it, but snakes sometimes shed theirs in one piece – kind of like how we take off our socks! As humans grow, our skin stretches with us and continues to grow as well. As a snake grows, it’s skin stays the same size and eventually, new growth is not possible and the snake is forced to shed. Snakes also shed their skin to get rid of any parasites on their skin. Parasites are organisms that steal their food from the organism they are living on or inside of. 

How can you tell when a snake is going to shed? A snake’s eyes will turn a blue/milky color when they are ready to shed. Why do their eyes turn this color? Snakes have a protective scale over their eye and when the old eye scale starts to separate from the newly formed scale it has fluid buildup and causes the blue/milky color we see (Image 1). During this time period at River Legacy, we try not to handle our snakes because they cannot see and this can sometimes cause distress in the snake. When snakes are in the wild and are close to shedding they usually hide to avoid being attacked by predators. 

Snakes shed for their whole life, but as they get older it slows down. How often a snake sheds depends on the type of snake as well as their age. Young snakes may shed 1 to 2 times a month and older snakes may only shed 2 times a year. If you’re interested in learning more about snakes, please join us for our Spring Break Activities: Reptile Day, during the week of March 9-13! Stay tuned for more information about specific times.

This post was written by Samantha King, River Legacy Living Science Center naturalist.

Image 1. Raj, the corn snake with blue/milky eyes

Beautiful Beetles

Beetles. Everyone is familiar with them. From the time most of us start hearing about bugs and insects, beetles usually come up among the first groups we learn about. This makes perfect sense as there are roughly 400,000 species of them worldwide. To put this in perspective, this means that about 40% of all insect species, and 25% of all animal species are beetles!

River Legacy Parks is home to countless beetle species, but there is a group of them that is particularly intriguing and special. These are the bess beetles, which belong to the Family Passalidae. They are a bright dark color and usually measure about 1 1/2 inches in length. Though most bess beetles are found in the tropics, there are some North American representatives. The River Legacy woods are among the places where they can be found in Texas. Bess beetles can be found inside of rotting logs or stumps. They are found there for two main reasons: 1. They consume decaying wood as part of their diet and 2. the females have to get into those tunnels and lay their eggs.

One of the most fascinating things about these beetles is they take care of their offspring. Bess beetles are considered to be presocial. This means that they exhibit some aspects of a social structure beyond just mating, but are not fully social insects in the same way as ants, bees, wasps, and termites. The vast majority of insects do not take care of their offspring so this aspect sets the bess beetles apart.

Due to their color, sometimes they are hard to spot. But, if you look closely around a decaying log, you might be able to spot them. Any time of the year is a good time because decomposition is happening all the time! However, several have been spotted lately by our River Legacy staff. See if you can find them as well!

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Are Some River Legacy Trees Haunted?

After a brief late summer hiatus, we are back! Fall is fast approaching and one of the many things people anticipate with fall is Halloween! Though it is only September, if you walk around the trails of River Legacy, you might notice that some trees look like they are covered in spider webs, and a lot of them. Is the forest getting ready for October 31st? While we would like to think so, these webs are a really cool natural phenomenon.

 

Often confused with spider webs, these webs are actually made by the caterpillar of the fall webworm moth (Hyphantria cunea). These caterpillars can produce webs that sometimes cover huge swaths of trees. They measure about 1 inch long and start eating leaves immediately after they hatch from an egg mass. The web is produced to form a cover on the areas where they are feeding. Host trees include mulberry trees, oak trees, pecans, sweetgum, redbud, willow, and many other fruit-bearing trees. This can be seen in late summer and early fall, but it can depend on the location. For example, trees in the southern part of Texas start appearing with these webs as early as April.

 

Right now, the easiest place to find these webs are in areas alongside Snider Creek on the eastern side of the trail adjacent to our new parking lot on Margaret Drive, at the main entrance to River Legacy Parks. But keep your eyes open, because they have appeared in many other parts of our forest in previous years. So, while you might think these trees are Halloween decorations, they are just mother nature’s work for all of us to marvel and learn!

 

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Baby Praying Mantis!

Students in 3rd and 4th grades will be learning some amazing facts about insects in our Insect Investigators Summer Class this July! Did you know that summer is a very important time for the life cycle of many insects, especially the praying mantis.

Baby mantis seen against the backdrop of a leaf

Mantises (order Mantodea), first lay their eggs in autumn, which start to hatch in the spring. Late spring and summer, the nymphs (baby mantises) are in a period of growth and development and they tend to be seen more often because of this.  The babies hatch from an egg sac that is produced by the mother mantis using a special secretion from her abdomen. This egg sac is known as the ootheca. Color typically varies, but babies tend to be a different color than the adults. As the nymphs keep growing, they molt their exoskeleton. Depending on the species, some mantises can live from about 4 to 6 months but smaller species average a lifespan of only about 4 to 8 weeks.

When you visit the Science Center, look around the Turk’s cap plants on the outside terrace. Nymphs will tend to be underneath leaves or sitting on stems and they are fairly difficult to find due to their size and great camouflage. Nevertheless, with some patience, it is very possible that you will come across one. In addition, if you have children that would be interested in learning more about mantises and other amazing insects, our Insect Investigators summer class from July 15th to the 19th still has some open spots. Call 817.860.6752, ext. 102 to register or visit our website!

Spectacular Spiders: The Dark Fishing Spider

Dark fishing spider (Dolomedes tenebrosus)

River Legacy Park is home to hundreds of spider species. One very common spider species is the dark fishing spider (Dolomedes tenebrosus). This spider is primarily found on trees and it is most often seen in the month of May, although it can also be spotted all the way until September. Despite the fact that it is called a “fishing spider,” it does not live near water or fish. It is in fact, the most terrestrial, of the fishing spiders. It is quite big: females can measure anywhere from 15 to 26 millimeters whereas the males tend to be smaller, from 7 to 13 millimeters. The female produces egg sacs that can contain up to 1,000 baby spiders inside!

Spiders serve many purposes in the ecosystem at River Legacy, mainly prey control. It is estimated that all of the world’s spiders consume about 400 to 800 tons of prey each year! Spiders are also a great group of organisms for learning a wide array of concepts: predation, invertebrate biology,  how venom works, the amazing design abilities of the animal kingdom, etc.. Learning about spiders can help in reducing arachnophobia.

During our Spectacular Spiders Summer Class, students will learn all about spiders and why they are cool and interesting. Space is filling up quickly though so visit our website to sign up and learn more information. We hope to see your child there!