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!

Beautiful Autumn Colors

As we welcome December, the end of fall is fast approaching. In fact, there are only 17 days left of autumn. While River Legacy and North Texas in general do not see much traditional autumn foliage, there are a few trees that exhibit some fall hues. By now, most of the leaves have begun to fall to the ground, but there are still some trees with their green, orange, brown, red, or yellow foliage.

But, what drives the leaf color change? It has to do with the chemistry inside the leaves and how it responds to seasonal changes. Leaves contain many pigments, including chlorophyll as well as carotenes, xanthophyll and others. Chlorophyll is probably the one most of us are familiar with. This is the pigment that gives leaves their green color. When a plant undergoes photosynthesis, the process by which it creates its own food, chlorophyll takes center stage. It absorbs energy from the sun’s rays to be used in creating this food. As autumn approaches, the temperature gets cooler and the length of sunlight the leaves receive shortens. This causes chlorophyll to break down, making the green color go away. So, leaves are left with the other pigments and these become visible. Carotenes and the other pigments give leaves their yellow to orange colors in the fall. There are other chemical processes at work that add the red hues that are commonly seen as well.

Eventually, the leaves break off the tree. Since trees will no longer be able to make their food during the winter, they go into a state of dormancy where their metabolism slows down. It is a process that is very similar to animal hibernation. The trees are not dead during this time, contrary to what it might seem.

Before all of the leaves fall in a few days, come take a walk at River Legacy to catch a glimpse of some of the beautiful tree color changes in the park and Science Center grounds.

 

Amphibians of River Legacy

River Legacy is home to a wide variety of animals. Though big mammals and such as armadillos, bobcats, raccoons and others are among the most iconic inhabitants of River Legacy, several equally-awesome amphibian species make this park their home.

But, first, what are amphibians? Amphibians are a class of vertebrates (animals with a backbone) that are cold-blooded, live semi-aquatic lifestyles, and have a moist and scale-less skin. There are three kinds of amphibians in the world: frogs and toads; salamanders; and caecilians.

Gulf Coast Toad

Here,  only two of those kinds can be found – frogs and toads and salamanders.

Frogs and Toads

Several frog species can be found in our forest. Frogs and toads will usually be found near or in a body of water or a moist area. Some can be seen hopping by the trails or in our pond. Here are some of the most common species: Gulf coast toads (Incilius valliceps) are native to Central America but they have become established in North-Central Texas, including River Legacy. Other common species include the southern leopard frog (Lithobates sphenocephalus) and the American bullfrog (Lithobates catesbeianus). Additional species include the Texas toad (Anaxyrus specious), green tree frog (Hyla cinerea), gray tree frog

Blanchard’s Cricket Frog

(Hyla versicolor), and the Blanchard’s cricket frog (Acris crepitant blanchardi).

Salamanders

Salamanders look like lizards but they are not covered in scales. They are less diverse and common than frogs and toads. One of the common species found in River Legacy is the barred tiger salamander (Ambystoma mavortium).  River Legacy is part of the range of other species, but no records have been reported.

Visit River Legacy Living Science Center to see the amphibians in our animal exhibits!

Why Do Nocturnal Animals Come Out at Night?

As with most animal behavior, it comes down to survival. Whether it’s avoiding being eaten by another animal or being able to find food, nocturnal animals have plenty of good reasons to sleep during the day and hunt at night.

Temperature

Many reptiles sleep during the day to avoid the hot afternoon temperatures. For example, Copperhead snakes spend much of the daytime sleeping under logs and leaf litter. Then they forage for cicadas and small rodents at night.

Predators

Animals such as mice are nocturnal because many of their predators are out during the day. While there are also predators at night, these small animals have a better chance of going unnoticed as they forage for food and water. During the day they can rest safe and sound within their burrows and at night they can search for food.

Prey

Some animals also come out at night because their prey comes out at night. For example, owls hunt for mice at night, which also happen to be nocturnal. Catching prey at night can be more difficult, but nocturnal predators are equipped with adaptations like great hearing and eyesight.

Competition

Animals are nocturnal because there is too much competition during the day. For example, bobcats might hunt during the daylight so coyotes hunt at night. This allows each species the chance to hunt for food without constantly fighting each other.

The coyote picture shown above is from one of our night trail cameras at the Science Center which captures still photographs. Trail cameras are predominately used to watch and track wildlife. They are perfect to place in a remote location and see what wildlife is in the area. It is surprising what you will see and how much wildlife is around us at night.

 

Bobcat Sighting

This beautiful bobcat was spotted earlier this week near River Legacy Living Science Center. We only got this quick glimpse before it sauntered back off into the woods.

If you should see a bobcat along the trails of River Legacy Park, this is what you should do:

  • Quietly watch or photograph the animal from a distance.
  • Make sure the bobcat has an “escape route” and do not try to corner it,  approach it or throw anything at the animal.
  • Never approach a mother bobcat that has cubs. She will try to protect them if she feels you might be a threat.
  • Never feed bobcats or any wild animal. They have plenty of natural food sources (rodents,  squirrels, birds) in River Legacy Park.
  • Enjoy the experience! Bobcats are solitary animals with a territory of up to 25 square miles. They are usually well camouflaged and avoid human contact so you are privileged to see this remarkable animal in the wild.

The bobcat’s most distinctive characteristics are a tuft of fur on each ear and a bobbed tail.

Let us know of your cool bobcat sightings!

Snake Sightings on the Rise

No alarm needed, just a dose of caution,  if you spot a snake on the park trails or even in your own backyard. Like most wild animals, snakes are more afraid of you than you are of them.

Just like checking weather conditions and packing enough water are necessary steps to prepare for any outdoor outing, so should being aware of the wildlife you may encounter. The first thing to keep in mind is that these are wild animals, and wild animals need space. If you encounter a snake along a trail, be sure to observe from a distance. Most snakes will move quickly off the path while others might stay as still as possible. If you can, walk around the snake, giving it a wide berth.

The best course of action is to leave it alone and observe or take pictures from a distance. Most snake bites occur when people try to pick up, move or kill a snake, all of which are unnecessary. Another way to avoid snake bites is to always be mindful of where you are stepping or placing your hands while hiking a trail that is either paved or off-the-beaten path. Be sure to look where you are walking and never reach down to grab something unless you have complete visibility.

Many snakes, like copperheads, like to bask in the sunlight and can be found doing so stretched across a trail, log, or parking lot. Copperheads are venomous but are not aggressive. Rat snakes are another common snake spotted in this area. Rat snakes are non-venomous, help control the rodent population and have excellent camouflage. They are typically spotted climbing trees or sliding across your backyard or trail.

Learn more about snakes common to our area at River Legacy Living Science Center and check out our exhibit of snakes, as well as other wildlife native to River Legacy Parks.