Posts Tagged ‘reptiles’

A Flash of Blue

Friday, June 17th, 2011

During June and July, eggs of the Five-lined Skink (Plestiodon fasciatus) hatch, producing tiny black and white striped offspring with metallic blue tails. These small lizards are often common in yards, on logs in the forest, and on the sides of trees. When approached, they rapidly disappear into leaf litter or under a log. What we often see is just a blur of blue.

Juvenile Five-lined Skink

Juvenile Five-lined Skink

The black and white stripes fade as the skinks get older, and just after they reach sexual maturity, their tails fade to match the brown body coloration. Why are the juveniles so brightly colored in the first place, and why do they lose this coloration?

Adult female Five-lined Skink

Adult female Five-lined Skink

If you watch a young skink for a while, it will go in and out of leaf liter looking for small insects. When its body goes into the leaf litter, it will move the tail back and forth on the leaf litter. If a bird or other predator has been watching the lizard, the blue tail signals that the skink knows a predator is near and that it likely can escape if attacked. If the bird attacks anyway, it may get the tail but the lizard will escape and grow a new tail. Losing a tail doesn’t cost a young skink very much in terms of energy. So this is the answer to the first question. The bright coloration distracts a predator away form the body of the skink to the tail, which can be re-grown if lost.

As these skinks grow and lose their juvenile coloration, they tend to become cryptic. That is, they match the background colors of the forest and are much more difficult to see. They are also more experienced because they are older. Adults store fat in the tail, and that fat is used by males for reproductive related behavior, and by females, to produce eggs. As a result, losing a tail as an adult is expensive energetically and it can affect their ability to reproduce in a given year. They also can grow back their tails if they should lose them, but they might have to skip a year of reproduction. Consequently, the tail in adults is an important fat storage organ, so good reasons exist to not attract attention to it.

Small Yard Snakes

Friday, June 17th, 2011

Especially during Spring and Fall, we often see very small snakes, either on the sidewalks in morning or afternoon, or in our landscaping, often under rocks and other surface objects. We are talking about snakes about as big around as a pencil and usually less than one foot long. What the heck are they, and what are they doing in your yard?

The answer to the first question varies with where you live. In the immediate vicinity of Norman, Oklahoma and in most of the eastern half of the state, those small snakes are usually adults of several possible species. The first, and easiest to identify, is the Ring-necked Snake (Diadophis punctatus). It is dark gray or bluish on top with a narrow orange or yellow ring around its neck. If you bother it, it will coil its tail and turn it over exposing bright red to yellow underparts. The entire underside of the body is red to yellow with some black specks running down the belly. Ring-necked snakes eat small invertebrates, such as earthworms, spiders, and insect larvae, but they can take very small vertebrates.

Ring-necked Snake—note the obvious orange ring around the neck

Ring-necked Snake—note the obvious orange ring around the neck

If it is not a Ring-necked snake, the next thing to look for is some sort of pattern on the back of the body. If it has a pattern, then it most likely is a Brown or DeKay’s Snake (Storeria dekayi). Although the body color can vary from light tan to brown or even reddish, a lighter colored stripe will run down the midline of the back and the head will be darker than the rest of the body. However, look closely at the head and the tip of the tail, because the possibility exists that it may be a juvenile Pigmy Rattlesnake (Sistrurus miliarius). If the head is triangular shaped and it has a tiny rattle on the end of its tail, then is it a Pygmy Rattlesnake and you should leave it alone. Brown Snakes mostly eat earthworms.

Brown or DeKay's Snake

Brown or DeKay's Snake

This leaves two small snakes, both of which are solid gray on top, with no obvious markings. One will have a slightly flattened (but not diamond-shaped) head that is a tad darker than the body. It will also have very small, beady black eyes, and if you turn it over, it will have a pinkish belly. This is a Flat-headed Snake (Tantilla gracilis). These eat centipedes.

Black-headed Snake—look for the pink belly

Black-headed Snake—look for the pink belly

The last common small snake is the Rough Earthsnake (Virginia striatula). These can be very common, often several under a single rock. They are gray, brown, or reddish with no obvious markings and the belly is a light tan (never pink). These eat earthworms, slugs, and insect larvae.

Rough Earthsnake

Rough Earthsnake

So, the next time you see a small snake while working on your landscaping, give it a close look and then come back to this blog. You should be able to identify it and assure yourself that it is something that belongs in your yard. And remember, these are all about as big around as a pencil, or less!

“Kingsnakes”

Thursday, June 16th, 2011

Kingsnake is one of those snake words that is thrown around a lot. One of the most common things we hear about “kingsnakes is that they are cannibalistic because they eat other snakes. Technically speaking, kingsnakes are snakes in the genus Lampropeltis, and many species exist. They include Speckled Kingsnakes (L. getula), Prairie Kingsnakes (L. calligaster), California Mountain Kingsnakes (L. zonata), Arizona Mountain Kingsnakes (L. pyromelana) and even Milksnakes (L. triangulum).

Oklahoma has Speckled and Prairie Kingsnakes as well as Milksnakes, and all three occur across most of the state. Speckled Kingsnakes are black with yellow “speckles,” usually one on the back edge of each black scale. Prairie Kingsnakes have a background color of brown and have distinct blotches in the western part of Oklahoma but are often very drab with only a faint hint of blotches in eastern Oklahoma. Both of these can reach 3 feet in total length or more. Milksnakes have red, white, and black bands that do not extend across the belly. They usually do not exceed 2 feet in total length. These brief descriptions and the photographs in this blog, should make it rather easy for you to identify the three kingsnakes in the state.

An adult speckled kingsnake from eastern Oklahoma

An adult speckled kingsnake from eastern Oklahoma

An adult prairie kingsnake from central Oklahoma

An adult prairie kingsnake from central Oklahoma

A sub-adult milksnake from southeastern Oklahoma

A sub-adult milksnake from southeastern Oklahoma

So, what about cannibalism? It is the case that most kingsnakes eat other snakes as well as lizards, mice, and even frogs occasionally. However, the various species of “kingsnakes” usually do not eat their own species, so technically speaking, they are not cannibals any more than you or I are cannibals because we eat beef. All species of kingsnakes can discriminate between their own species and other snake species by use of a highly developed chemical sensing system. They touch other snakes with the tips of their forked tongue, bring chemicals into their mouths, and deposit those chemicals on the surface of a large and highly developed chemical sensing organ known as the vomeronasal or Jacobson’s organ. This organ transmits information to the snake brain (yes, snakes have a brain!), where the information is used to identify whether the other snake is a species that they want to eat or whether it is one of their own species. This same chemical sensing system is used to locate and identify mates during the breeding season.

Dodging Turtles

Tuesday, May 17th, 2011

With the days getting warmer, box turtles begin moving around, often finding themselves on paved highways as they search for mates and good areas to feed. Not to be confused with rocks, box turtles will squish when run over. Similar to most other reptiles (and, interestingly Opossums and Armadillos), box turtles are oblivious to traffic. This might seem surprising, considering that turtles in general have excellent sight. For example, if you try to sneak up to a bunch of sliders basking on a log in a pond, you will be lucky to get within 100 yards of the turtles before they “slide” into the water. Of course, box turtles cannot slide into the water because they spend most of their time on land. Nevertheless, they see you from a long distance when approaching. When a box turtle detects something moving within the range of its eyes, it remains perfectly still, with its head up in a periscope-like fashion as shown in the first photo below. Box turtles are difficult to detect in their natural habitats if they do not move. If you are lucky enough to see one, by the time you get your camera set to photograph it, the turtle will likely pull its head and legs into the shell and close it.

Ornate Box Turtle with head up, remaining motionless in an attempt to be overlooked.

Ornate Box Turtle with head up, remaining motionless in an attempt to be overlooked.

Oklahoma has two species of box turtles, the Ornate Box Turtle, which is most common in western Oklahoma, and the Three-toed or Eastern Box Turtle, which is common in central and eastern Oklahoma. Both species occur in central Oklahoma, but the Ornate Box Turtle is less common. Like most animals, box turtles usually know where they are going when they head out across a highway. Given that an adult box turtle might be 40 years old or older, the highway may not have even been there when it hatched from an egg. Even if the highway is older than the individual turtle, neither highways nor cars are in the evolutionary history of box turtles. From the perspective of a box turtle, a highway is just a strange piece of ground that they have to cross to get where they are going.

Three-Toed Box Turtle caught in the act of feeding on some vegetation along the edge of a small pond. Three-toed Box Turtles are highly variable in coloration.

Three-Toed Box Turtle caught in the act of feeding on some vegetation along the edge of a small pond. Three-toed Box Turtles are highly variable in coloration.

How can you help? The best thing that you can do to help box turtles, is to watch for them on roads when either driving or sitting in a car. When you see one, the first thing to do is avoid running over it. If there is no traffic, you can stop and help it across the road. If you do stop and move a turtle (of any kind) be sure to set it well off the road and on the side it was heading for. However, keep in mind that roads and highways are dangerous for people as well, and you should not stop if doing so puts you in harm’s way. Simply paying attention and doing your best to avoid running over turtles goes a long way in helping them out. In addition, tell everyone that you know to start watching for and avoiding turtles on the highway.

Three-toed Box Turtle upside down with the shell completely closed. The lower shell (plastron) has two hinges which allow the turtle to close itself in the shell. Most turtle species cannot completely close the shell. Box turtles close the shell immediately when first disturbed and often remain this way for an hour or more. When they do come back out, they first partially open the front of the shell and peek out to see if they are safe.

Three-toed Box Turtle upside down with the shell completely closed. The lower shell (plastron) has two hinges which allow the turtle to close itself in the shell. Most turtle species cannot completely close the shell. Box turtles close the shell immediately when first disturbed and often remain this way for an hour or more. When they do come back out, they first partially open the front of the shell and peek out to see if they are safe.

Why should we care about turtles? First and foremost, turtles are part of the natural biodiversity of the planet, and as such, they play important ecological roles as grazers on fruits and predators on certain insects and other invertebrates. Second, they were here first. The first turtle fossils appeared in the mid Triassic, about 225 million years ago. Box Turtles are in the family Emydidae, which also includes Sliders, Painted Turtles, and Map Turtles, to mention a few. The family Emydidae dates back to at least the late Cretaceous, some 75–80 million years ago. The family that we belong to, the Hominidae, dates back only about 15 million years, and modern man (Homo sapiens) as we know it, dates back less than 200,000 years. Box turtles certainly have been in Oklahoma long before the influx of Europeans and even long before Native Americans settled the land. So, as Woody Guthrie sang in 1940, “This land is your land, this land is my land…”—we share the land with box turtles and all other native animal and plant life, and we should do our best to maintain that relationship.

“Spreading Adders”

Thursday, April 29th, 2010

The hiss of an Eastern hog-nosed snake as it spreads its neck and acts like a cobra can be quite startling, but it is all bluff. Eastern hog -nosed snakes are completely harmless, and it is nearly impossible to get one to bite. It is no accident that they seem to show up when toads are active. Hog-nosed snakes specialize on toads, eating almost nothing else. Colors and patterns of hog-nosed snakes vary from nearly all black to reddish with various shaped markings, and younger hog-nosed snakes seem to be brighter in color than older and larger ones.

An adul;t (top) and juvenile (bottom) Eastern hog-nosed snake

An adult (top) and juvenile (bottom) Eastern hog-nosed snake

When first disturbed, hog-nosed snakes go through their hissing and spreading display, hence the nickname “spreading adder.” However, if they are bothered a bit more, they switch their behavior to a ridiculous series of movements in which they appear to act as though they have died, going so far as to roll over on their back, open their mouth, drag their tongue in the dirt and lay there motionless. If you wait a few minutes, they will roll their head over and look at you. If you roll them over so that they are upright, they quickly roll back over upside down. And, if you wait long enough, they roll over and crawl away. What could possibly be the advantage of doing this? One would think that simply lying there would make it easier for a predator to eat them.

Starting in the bottom left, follow clockwise, the deith-feigning sequence of a hog-nosed snake

Starting at the bottom left, follow clockwise, the death-feigning sequence of an Eastern hog-nosed snake

If you watch carefully when hog-nosed snakes first start rolling over, you will notice that they cover themselves with bodily wastes released from their cloaca as they twist and coil during their death feigning act. Recall that they eat toads, almost exclusively. Toads eat ants and beetles that produce chemicals (alkaloids) for defense, and toads in turn produce strong chemicals that are released from the large glands (paratoids) just in back of their head that make them very bad tasting and sometimes toxic (don’t lick a toad!). So, when Hog-nosed snakes eat toads, they are also eating a bunch of very bad-tasting chemicals. By covering themselves with excrement, Hog-nosed snakes make themselves very bad to eat. The “playing dead” likely keeps them from being injured while a predator determines that they are not as tasty as they first appeared to be when they were crawling along.

Threat display of an adult Eastern hog-nosed snake. Note the raised tail and the flattened neck, hence, "spreading adder."

Threat display of an adult Eastern hog-nosed snake. Note the raised tail and the flattened neck, hence, "spreading adder."

Mole salamanders

Wednesday, April 21st, 2010

In an earlier blog, we mentioned that Spotted salamanders (Ambystoma maculatum) were making their way into ponds to breed. We thought that we might tell you about not only Spotted salamanders but also about the family of salamanders that they belong to, the Ambystomatidae. These amphibians are collectively known as “mole” salamanders because they spend much of the year underground. This family is distributed throughout most of North America and contains 37 species. Oklahoma has six species.

Four of the six species of mole salamanders in Oklahoma

Four of the six species of mole salamanders in Oklahoma

Among the Oklahoma species of mole salamanders, some breed in late winter, like the Spotted salamander and the Small-mouthed salamander (A. texanum), some breed in fall, like the Marbled and Ringed salamanders (A. opacum and A. annulatum, respectively), and some breed in spring, like the Tiger and Mole salamanders (A. tigrinum and A. talpoideum, respectively). When they are breeding, many hundreds seem to appear from nowhere. Considering how many arrive at the breeding ponds, it seems that they could be found any time during the remainder of the year—not so! After adults breed in ponds, they leave the ponds and go underground, not to be seen until the next breeding event. Obviously, they must feed while underground in order to grow and save energy to reproduce next time, but very little is known about their underground activity. Some, like Tiger salamanders, are known to live in gopher burrows, often in large numbers, but for the rest, we know very little.

After the breeding events, eggs hatch in ponds, and thousands of tiny salamander larvae emerge. Larvae of all species of mole salamanders look superficially alike, and a bit of skill is required to identify the different species in larval form. They have external gills, a laterally compressed tail that aids in swimming, and when not slowly walking on the pond bottom, they swim with an undulating motion, similar to that of alligators. Temporary ponds are filled with tiny invertebrates, collectively called microinvertebrates, such as ostracods, copepods, and Daphnia (a genus of cladocerans). Larvae of mole salamanders vacuum up these tiny invertebrates by opening the mouth and expanding the throat at the same time. They close the mouth and expel the water out through the gill slits, but retain the prey items. Their diet includes nearly every kind of pond organism small enough to fit into their mouths.

Larvae of Mole salamanders grow rapidly, but should rain be scarce, their pond might dry up before they are large enough to transform into adults. Ponds are also filled with predators that eat salamander larvae, including watersnakes, bullfrogs, giant waterbugs, and larvae of dragonflies and predaceous diving beetles. Some species of birds also visit ponds and capture salamander larvae. As salamander larvae grow, it is less likely that they will be captured and eaten by an insect. Large larvae are particularly attractive to birds and snakes. Life in the pond is risky for salamander larvae, and the best thing to do is grow fast and leave the pond as quickly as possible.  Of the thousands of eggs that are deposited each year, some will survive to become adults and breed, and most won’t. Variation among individual offspring sets the stage for natural selection.

Larva of a Tiger salamander

Larva of a Tiger salamander

The First Spring Rains Bring Out Frogs and Salamanders

Wednesday, April 21st, 2010

Rains that occurred several weeks ago in southeastern Oklahoma brought out all of the early spring frogs, including Spring peepers (Pseudacris crucifer), Cajun chorus frogs (Pseudacris fouquettei), Pickerel frogs (Lithobates palustris), and Southern crawfish frogs (Lithobates areolata). Even Southern leopard frogs (Lithobates sphenocephala) and American toads (Anaxyrus americanus) were active. In addition to running our traps at our primary research site in Le Flore County, we spent time driving roads at night in both Le Flore and McCurtain Counties. Nearly every roadside pond contained some mix of the above frog species. The only two that did not occur together were Pickerel and Crawfish frogs.

An adult Cajon chorus frog

An adult Cajun chorus frog

A number of amphibian species in Oklahoma breed during late winter and early spring, and their nearly deafening choruses can be easily experienced by driving around in rural areas at night. Males congregate in ponds when rains first begin, and their calls attract females that have spent the fall and winter converting energy that they stored from spring, summer, and fall activity into eggs. Examination of ponds during the daytime usually reveals many egg masses attached to vegetation or floating on the pond surfaces.

In addition to frogs that reveal their presence by calling, salamanders are moving into ponds to breed. We found large numbers of Spotted salamanders (Ambystoma maculatum) moving across roads heading for ponds during rains, and we captured some in our traps. Unlike frogs, salamanders do not vocalize. Whereas female frogs are attracted to individual males by the quality of the call, female salamanders are attracted to individual males by the quality of their courtship behavior.

An adult Spotted salamander

An adult Spotted salamander

So, for those of you are interested in amphibians, drive around in rural areas when it begins to rain and listen for frog choruses.  With the windows cracked, you can hear choruses in breeding ponds along the roads.  If you find a chorus on public property, put on your boots, turn on your good flashlight or headlight (preferred), and see if you can locate individual frogs that are calling. Chorus frogs are tiny and usually call inside grass clumps at the surface of the water. A Chorus frog calling right at your feet can be difficult to locate and requires persistence. If you are lucky enough to hear the low snoring calls of Pickerel or Crawfish frogs, you will need to move slowly without sloshing the water.  Even slight movement of the water caused these wary frogs to stop calling and dive below the surface. If you stand quietly for ten minutes or so, males will reappear and begin calling.

Sirens galore!

Tuesday, April 20th, 2010

Several weeks ago, a group from the museum visited the ODWC’s Red Slough in search of some salamanders that only occur in swamps of the southeastern part of Oklahoma. We were able to trap more than 20 sirens, which are elongate, eel-shaped salamanders that live their lives in water. They are in their own family, the Sirenidae, and the species that occurs in Oklahoma is the Western lesser siren, Siren intermedia.

Adult Lesser siren

Adult Western lesser siren

Unlike eels, sirens have external gills and a pair of tiny front legs, that on first glance, appear useless. Believe it or not, they use these legs on rainy nights when they move short distances across land. These sirens can reach eight inches in length, but most are slightly smaller. In most salamanders that have aquatic larvae, external gills used for respiration in water are lost when the salamanders metamorphose into terrestrial adults. In sirens, no obvious metamorphosis takes place, with the adults looking exactly like the “larvae,” just larger in size. However, close examination of the internal morphology reveals that reproductive organs develop as the “larvae” increase in size and age. Consequently, they do “metamorphose” but retain some larval characteristics (external gills).

Sirens reach sexual maturity in about two years. They deposit from 100–200 eggs in cavities in mud at the bottom of swamps. One of the most interesting aspects of the biology of sirens is their ability to form a cocoon around their body when swamps dry up. They burrow into the mud and secrete mucous that forms the cocoon, the function of which is to prevent them from drying up. Sirens can remain inactive for as much as eight months in their cocoon until rains fill the swamps that they live in.

Although sirens are difficult to observe because they are under water, they can be easily trapped with minnow traps, and no bait is needed. If you should trap one to observe, be sure to keep it in water that contains oxygen and is not chlorinated. It might also be useful to drop a few dried pine needles or oak leaves into the aquarium as tannins released from needles and leaves can keep mold from attacking the skin of sirens and other aquatic amphibians and reptiles.

Head of Lesser siren showing external gills

Head of Western lesser siren showing external gills

Blog Readers, we are back!

Tuesday, April 20th, 2010

Just after our last blog, rains brought frogs and salamanders out all over the place, which sent us racing around different parts of southeastern Oklahoma. We also ran our drift fence traps at our field site in Le Flore County, trying to keep up with movements of amphibians. A brief trip to Florida to present a talk to one of the Florida herpetological societies in Gainesville interrupted our amphibian and reptile excursions in Oklahoma, but only for about a week. As a result, we have been so busy that we have not been able to keep up with our blog. However, as the title says, we are back, and we will try to catch you up on what we have been doing in the following series of blogs. We hope you will all stick with us, and many thanks for all of your kind comments.