Frog Calls Newsletter of Crosstimbers Connection Volume 1, No. 3
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July, 2013
The Search for Summer Frogs With Nolan High School Students at Fort Worth Nature Center & Refuge
Heidi examines a toadlet
On June 22, Crosstimbers Connection teamed up with the Fort
Then we moved on to the bottomland woods at the north end of
Worth Nature Center & Refuge to provide some students a wet-
the marsh. Hopping across the trail was a very small toadlet,
land outing in search of frogs and toads. Five biology students
which was a toad that had just metamorphosed from a tadpole
from Nolan Catholic High School, along with teacher Bill Richer-
and was still small enough to sit on your fingernail, if we could
son, came to learn about local anurans (frogs and toads) and
just get it to sit still. We also found a couple of little brown skinks
their calls. We showed pictures of lots of these amphibians and
slithering around in the leaf litter with their tiny legs and long
listened to recordings of their calls.
bodies. Exploring around a dry place where running water had previously made clumps of branches and leaves, we found a
Afterwards, we visited several places on the refuge, starting with the marsh boardwalk. In the gravelly area near the parking lot we spotted a six-lined racerunner, an alert and fast lizard with stripes down its back and a beautiful wash of yellow-green on its shoulders and head. On the boardwalk we saw and heard insects, birds, and fish, and though we looked for green treefrogs, we did not see any.
white-footed mouse. This mouse, with white fur along its underparts and big dark eyes, paused for a photograph before scampering off. There were a number of invertebrates to find, including a beautiful underwing moth on a big tree trunk. At one point, Debbie spotted a three-toed box turtle wandering through the woods in the late afternoon shadows.
Frog Calls
July, 2013
The Search for Summer Frogs (continued)
We took a walk on Greer Island at the end, as the light of day was failing and it was time to use our flashlights to find our way. We started hearing the “wank-wankwank” of green treefrogs, and by the time it was fully dark, on the causeway off the island, the reeds to our left were loud with the choruses of these beautiful green frogs. White-footed mouse The students had been great, and we thanked each other for a good time before they boarded the bus for home. One girl said she appreciated our showing her
Underwing moth
this place, saying that she really had not had this kind of experience before. And this made our day – Mark, Debbie, and Michael went home very happy to have had a hand in sharing this place with these great kids.
Speaking of Green Treefrogs… We went on two "herp walks" on May 25th at Ft. Worth Nature Center & Refuge - each with a family with a couple of young children. We had fun checking out the boardwalk, talking about green treefrogs and then seeing them (and in one case getting to watch him call with his distended throat pouch). We showed one family a small leopard frog that they were thrilled with. They were equally thrilled with the five lined skink we got a glimpse of, the red-winged blackbird in the marsh, the various snails, and the kids loved the "roly-polys." Young kids have Green treefrog
a wonderful ability to see amazing things in some of the smallest creatures!
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Frog Calls
July, 2013
A Water Snake Copes with Summer Heat By Michael Smith
“It’s really getting hot” I said as we waded through shallow
will die. How do they manage to stay within a certain range of
pools under a blistering sun. The white limestone reflected
temperatures, if they are “cold-blooded”?
sunlight back up from the ground, making a sort of natural Let’s look at one of the water snakes living in that creek. While
oven with heat radiating from all directions.
it could hunt and move about easily in the morning when the “Yeah,” my friend answered, “Where are the deeper and cooler temperature was in the 80s, later in the day it would make pools in this creek?” Not only was it a fairly shallow creek, but
more and more use of shelters from the heat. As the rocks
the sun was also drying the pools and making them shallower.
became hot to the touch, the snake could find spaces under-
As a result, the water in some places was getting close to the
neath some of the bigger rocks where it was cool. Although it
temperature you would want for a good soak in the bathtub.
could not sweat in order to cool off, its body would lose heat to the cooler underneath side of the rock. Back within its best
There we were, making our way along a very hot creek while
temperature range, the snake would venture out to one of the
trying to maintain our optimum body temperature of Blotched water snake
98.6˚F. Our bodies have a very narrow range in which they can function well, so we have to have ways of warming when it’s cold and cooling when it’s hot. We are endotherms, meaning that we generate body heat to keep warm and use other strategies to keep cool, maintaining a nearly constant temperature. Getting too hot may result in “heat exhaustion,” with such symptoms as dizziness, nausea, and feeling faint. If we get even more overheated, our body’s ability to regulate temperature may fail so that we stop sweating, become very hot, and may die. In the field on hot days, we need to be careful to bring water and make use of shade and rest so that we avoid heat illnesses.
pools and hunt for fish, but the pool of warming water and the
So what about the snakes, turtles, and frogs we were looking
bright sunshine might gradually drive the snake’s temperature
for? Can they suffer from the heat? Absolutely! Reptiles and
back up. At some point it might find a ledge along the edge of
amphibians are ectotherms, meaning that they generate little heat within their bodies and their temperatures tend to match their surroundings. They can do OK within a range of temperatures, but they cannot function well if their body temperature gets outside that range. And if it is too hot or too cold, they
the water, or a tunnel back into the cool earth, escaping the heat again. During the hottest part of the summer, the water snake may rest within such tunnels or deep crevices throughout the day, coming out only at night to hunt food.
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Frog Calls
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A Water Snake Copes with Summer Heat (continued) In the mild Texas winters, the snake could have been active
ly “yes.” Think about the energy that is required for our bod-
from time to time on warmer days. Early in the morning, that
ies to do what they do. Muscle movement takes energy, as
snake might poke its head out from its hiding place and into
does the activity of all the internal organs. Our bodies are
the sun, to begin warming. The snake would be cool – not
like little engines that are constantly breaking down the food
dangerously cold but cool enough that it might be sluggish
that we eat in chemical reactions that provide us with ener-
in hunting and unable to shift into high speed to get away
gy. These chemical reactions are our metabolism. As endo-
from a predator. As the sun warmed the snake’s head, the
therms, our engines are running at a pretty high rate all the
circulating blood would carry heat to other parts of its body
time because we not only need energy for activity, we need
until it warmed enough to emerge into
it to maintain our internal temperature.
the sun. The little reptile might flatten
Reptiles, amphibians, and other ectotherms
its body, exposing more of its surface
use food energy primarily for activity, and
to the sun and warming further. In this
they can use sunlight and warmth from
way, it reaches a temperature that still
their surroundings to maintain a workable
might feel cool to us, but would be
body temperature. Our water snake used
warm enough to move quickly and use
the sun to raise its temperature when it was
its reptilian brain to interpret cues in its
active, and when inactive in a shelter it did
environment and decide where to go
not need to use its internal energy reserves
and what to do.
because it did not need to stay warm. During nighttime activity it still indirectly made
Reptiles have a variety of ways to regu-
use of the sun’s energy, getting warmth
late their temperature, including using
from the rocks and water that were
the sun to warm themselves and get-
warmed by the sun the previous day. A
ting away from the sun to cool. Some snakes shiver (use
human might need ten times more energy than the water
muscle contractions) to raise body temperature just a little bit while coiled around a clutch of eggs. Some reptiles can shift
snake, meaning that the reptile can get by on much less food than the mammal.
their color to become darker and absorb more sunlight. Once warmed, they may shift to a lighter color so that more
As we finished our day at the creek, we turned a big rock
of the sun’s energy is reflected away. If they become stressed and found a blotched water snake coiled beneath. He was in extreme heat, many reptiles may pant, bringing cooler air
not pleased about being caught and examined, and he let us
across the moist tissues of the mouth and losing some heat
know just how displeased by the usual tactics of biting and
that way.
discharging musk (they are nonvenomous and the bites just leave small scratches; the musk, however, is a bad smell that
Even though reptiles have a number of creative ways to regulate their temperature, they are still limited in what they can do during very hot or cold times and must rely on environments that offer lots of shelters and places to warm up. Is
stays with you much longer than the pain of the bites!). Knowing how hot it was, we replaced the rock and made sure to release the snake back into his cool refuge. Even a bad-tempered water snake should not have to flee for its life
there anything good about being an ectotherm? Does cold-
over hot limestone rocks.
bloodedness have some advantages? The answer is definite-
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How to go on a free outing with us: Contact us to plan an individualized outing We work with small groups, schools, clubs, or families to plan a specific date and location for an unforgettable experience in nature. Just contact us at: contact@crosstimbersconnection.org
The Skink Refuge This five-lined skink made good use of a hollowed-out section of a support post along the marsh boardwalk at the Fort Worth Nature Center & Refuge. This young lizard would retreat back into the post anytime someone came near, but at other times would emerge into the sunlight, heating up and getting ready to hunt for its next meal.
Crosstimbers Connection - Connecting People with Nature in North Texas We take people out into the woods and prairies, looking for reptiles, amphibians, and other wildlife, learning and having fun. And we do it without charging anything (but we gladly accept tax-deductible contributions to keep us going). We are a 501(c)(3) nonprofit organization - please visit us on the web at: http://crosstimbersconnection.org. Michael Smith, President - michael@crosstimbersconnection.org Mark Pyle, Vice President - markpyle@crosstimbersconnection.org Debbie Dorman, Secretary/Treasurer - ddorman@crosstimbersconnection.org Rob Denkhaus, Board Member
P.O. Box 151882
v
Arlington, Texas 76015
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