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Desert tortoises in the classroom

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My daughter just started Kindergarten this year, and like many schools in Tucson, they have adopted a Desert Tortoise. While I plan to utilize this wonderful resource in my own daughter’s classroom, other teachers or parents my not feel they have the expertise to use a live animal in their lessons. As a result, I put together the following information to give some suggestions to other parents and teachers. It is not necessary to be a biologist or tortoise expert to take advantage of this unique opportunity to teach children about desert wildlife and promote good stewardship of Nature. Most of the information was directly lifted from other sources (cited herein) and these are also excellent sources to find more information. Please disseminate this information to your local school and expand on it with your own ideas!
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SONORAN HERPETOLOGIST 26 (4) 2013 85
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Desert Tortoises in the Classroom
Prepared by Taylor Edwards, Tucson Herpetological Society ,Tuscon, AZ; taylore@email.arizona.edu
My daughter just started Kin-
dergarten this year, and like many
schools in Tucson, they have
adopted a Desert Tortoise. While
I plan to utilize this wonderful
resource in my own daughter’s
classroom, other teachers or
parents my not feel they have the
expertise to use a live animal in
their lessons. As a result, I put
together the following informa-
tion to give some suggestions to
other parents and teachers. It is
not necessary to be a biologist or
tortoise expert to take advan-
tage of this unique opportunity
to teach children about desert
wildlife and promote good stewardship of Nature.
Most of the information was directly lifted from other
sources (cited herein) and these are also excellent
sources to nd more information. Please disseminate
this information to your local school and expand on it
with your own ideas!
A school tortoise is an excellent classroom resource
and can be used as a teaching tool to:
1. Teach about the Sonoran Desert and its wildlife
2. Teach about science through the tortoise’s physical
attributes
3. Teach appreciation and stewardship of nature
4. Inspire creativity through art and writing
Natural History
What’s in a name?
A tortoise is a special type of turtle that has
evolved to live on land. Even though there are other
land turtles (e.g., box turtles) all tortoises share a com-
mon ancestor with each other and thus share similar
adaptations. You can say that, ‘All tortoises are turtles,
but not all turtles are tortoises.”
Look for the tortoise icon for classroom activities
EDUCATION
The type of Desert Tortoise native to the
Sonoran Desert in Arizona is Gopherus
morafkai. Photo by T. Edwards.
It is not neces-
sary to be a
biologist or tor-
toise expert to
take advantage
of this unique
opportunity to
teach children
about desert
wildlife and
promote good
stewardship of
Nature.
SONORAN HERPETOLOGIST 26 (4) 2013 86
The type of Desert Tortoise native to the Sonoran
Desert in Arizona is Gopherus morafkai. In the Mojave
Desert is a different species called Gopherus agassizii.
The word Gopherus is derived from the word gopher,
which in English is used to describe burrowing ani-
mals. All ve species of tortoise in the genus Gopherus
dig burrows. The other part of the scientic name (the
epithet) is named after a person: Dr. David Morafka.
Does the school tortoise use a burrow? How often?
What time of day/year? What can you nd out about
David Morafka? How about Jean Louis Rodolphe
Agassiz (1807-1873)? Note: Agassiz stated, “Study
nature, not books” and revolutionized natural science
education in the United States (See www.tortoise.org/
archives/gophname.html).
Morphology
Once mature, male and female tortoises can be
distinguished from each other by their physical ap-
pearance; called sexual dimorphism. Males have a
strong depression in the plastron that ts neatly onto
the convex carapace of the female. Males also have a
longer tail than females, and their gular horn is longer
and more curved. Males may also have prominent
chin glands that produce a secretion which aids in sex
recognition and often evokes combative behavior.
The mature female differs in having a at plastron, a
shorter tail, and an outward curve at the rear of the
carapace which probably provides a wider space for
egg laying.
Images from http://scienceray.com/biology/marine-
biology/turtle-anatomy/ and http://www.color2learn.com/
desert-tortoise-free-print-coloring-pages.html
Name the parts of the tortoises’ shell. Is the school
tortoise a male or female? How can you tell? Make
or draw a tortoise in the classroom that models their
anatomy; See http://blog.gummylump.com/2011/04/eric-
carle-inspired-foolish-tortoise.html
Behavior
Social behavior consists of a series of head bobs
for species and gender recognition, courtship, and
threat. Head bobbing normally precedes agonistic
(combative) behavior between males, although females
may also be aggressive. Male-to-male combat is most
intensive in spring and late summer in the Sonoran
Desert. During these encounters, each male stands
as high as possible, making short rushes toward his
adversary while attempting to use the gular horn at
the front of the plastron (undershell) to overturn the
other or drive him away. An overturned tortoise can
usually right itself using its head and a forelimb; if
not, the tortoise may overheat and die under the desert
sun. The Desert Tortoise produces a variety of sounds
(hisses, grunts, pops, whoops, huhs, echs, bips, etc.)
Carapace
which seem to be the most important when vocalized
to an unfamiliar tortoise.
Mating has been observed from early spring to
fall with the highest frequency in late summer in the
Sonoran Desert. Desert Tortoises normally construct
nests and lay eggs in May or June. The clutch size
varies from two to fourteen eggs with an average of
three to ve, although some eggs may not be fertile.
The eggs are hard-shelled, moisture proof, white, and
nearly spherical, about the size of a ping pong ball.
Ectothermy
Tortoises and other reptiles are ectothermic animals
which means that they control their temperature
behaviorally. This is also referred to as ‘cold-blooded’,
but this term has many negative connotations associ-
ated with it. In fact, ectothermy is a very efcient way
to regulate limited resources—tortoises are conserva-
tionists! This is one reason why reptiles are numerous
in the harsh and unpredictable desert environment.
SONORAN HERPETOLOGIST 26 (4) 2013 87
Use a temperature gun to take the temperature of
the tortoise (shell) and compare to the temperature of
its surroundings (den, shade, sun). How is the tem-
perature affecting the tortoise’s behavior? Note: Lasers
can be dangerous. Do NOT point the laser in the eyes
of the animal or people.
Brumation and Estivation
In the winter, Desert Tortoises brumate which is a
similar to hibernating except they can wake up to drink
water and return to “sleep”. They typically enter their
dens in October and emerge again in the spring. Es-
tivation is the counterpart to brumation but in warm
and dry conditions. Tortoises estivate by lowering their
metabolic rate to conserve energy during the hot, dry
season (May and June).
Have a school contest to see who can guess the
date that the tortoise emerges from its den after bru-
mation—like a groundhog day prediction of spring.
Lean sticks over the entrance that will fall down when
the tortoise exits. Note: In the Sonoran Desert, some
tortoises may not emerge until the monsoons (particu-
larly males). Tortoises may be ‘encouraged’ to emerge
earlier if there is available water and food. See http://
mojavemax.com/MojaveContest.html
In Arizona, tortoises are most active at the begin-
ning of the school year, August and September. By
about mid-October, their bodies are getting ready for
brumation, and they should not be disturbed. How-
ever, a tortoise can still be viewed in their burrow and
monitored by classes during brumation; use a hand-
held mirror to reect sunlight into the den to check
on a tortoise’s position, if it is awake, etc.). Activity is
less predictable in the spring, depending on tempera-
ture and rain. Once the tortoise exits its burrow in the
spring, it can be used in the classroom.
Age
Maturity in the wild is estimated to take 12-20 years.
Accurately determining the age of a wild or captive
tortoise is not possible because the size of the animal
depends upon growth rate and diet. However, age
can be estimated by counting the growth rings on the
tortoise’s scutes (or shields). Both wild and domesti-
cated tortoises develop roughly one growth ring on
each plate of the shell per year like the rings on a tree
stump (although in a given year they may add none to
several growth rings depending upon the quality and
quantity of food eaten). Eventually, rings wear and
weather. A tortoise with a smooth shell is considered
old. Tortoises live about as long as human beings.
Count the growth rings on the tortoises shell and
estimate the tortoise’s age. Students can make an
imprint with clay of the different scutes and compare
them. Does each scute have the same number? Does
each student count the same number or rings?
Diet
Desert Tortoises are herbivores and eat primarily
grasses; however, when available they will eat other
edible plants including spring and summer annual
wildowers, forbs, and cactus fruit. Desert Tortoises
derive some of their water intake from the plants they
eat. A large urinary bladder can store over 40% of the
tortoise’s body weight in water. During periods of suf-
cient rainfall tortoises drink copiously from tempo-
rary rain pools.
What does the school tortoise like to eat? What
plant species in the tortoises enclosure does the tor-
toise like or not like? Experiment with different desert
vegetation. Try globe mallow, cactus fruit, mesquite
pods, wildowers, native vs. exotic grasses, etc. Do
tortoises respond to different colored food? Note: this
should be a supervised activity, some common species
like oleander may be poisonous to tortoises.
Tortoise scat (or feces) can easily be found where
tortoises live. Breaking a dry scat open to see what the
tortoise eats is an excellent way to talk about tortoises
even if the animal is not active.
Predators
Although hatchling tortoises are preyed upon by
numerous predators, adult tortoises have few natural
predators (occasionally a desperate puma or coyote)
and have very low mortality rates. Their populations
are maintained by the fact that adults live a long time
and have many opportunities to reproduce over their
lifetimes. Unfortunately, increased mortality of adults
by human causes (hit by cars, etc.) can make it difcult
for natural populations to recover from a decline.
What about the shape of a tortoise’s shell makes it
a good defense against predators? The tortoise shell is
an excellent example of Nature’s architecture; arches,
buttresses, geodesic domes, keystones (See: http://
biocreativity.wordpress.com/2011/12/09/turtles-architecture).
Design a classroom experiment to test the strength
of arches using an egg shell. See: www.sciencebuddies.
org/science-fair-projects/project_ideas/MatlSci_p021.
shtml#summary
Desert Tortoises
are herbivores
and eat primar-
ily grasses;
however,
when available
they will eat
other edible
plants includ-
ing spring and
summer annual
wildowers,
forbs, and cac-
tus fruit. Desert
Tortoises derive
almost all their
water intake
from the plants
they eat.
SONORAN HERPETOLOGIST 26 (4) 2013 88
Conservation
Gopherus morafkai is currently a “candidate for list-
ing” under the U.S. Endangered Species Act. While
some remote populations appear to be stable, those
near urban or recreational centers have declined
signicantly. The Desert Tortoise is fully protected in
Arizona, and collection from the wild is strictly pro-
hibited without a permit issued by the Arizona Game
and Fish Department.
Threats to tortoises include loss and degradation of
the species’ habitat, through residential development,
drought, wildre, habitat destruction, fragmentation,
and invasion of exotic plant and wildlife species. Other
impacts on the species include removal of individuals
from the wild, vandalism, mortality from vehicles, ir-
responsible off-highway vehicle (OHV) use, release of
captive tortoises into the wild, and disease.
A common defensive behavior when molested or
handled is to empty the bladder, leaving the tortoise
at a considerable disadvantage in drier conditions. For
this reason, Desert Tortoises should not be handled
when encountered in the wild (unless moving out of
harm’s way, like on a road).
After learning about tortoises, have students take
the Tortoise Patrol Pledge:
As a proud member of the Tortoise Patrol, I prom-
ise to do these things to protect Desert Tortoises:
I will not take tortoises from the desert or hurt
their desert homes.
I will do my part to keep our deserts clean.
I will stay on the roads and trails when traveling
through the desert.
I will respect, protect, and enjoy our desert!
(See http://mojavemax.com/kids.html)
Tortoises as Pets
Thousands of tortoises are held in captivity in Ari-
zona. The Arizona-Sonora Desert Museum’s Tortoise
Adoption Program is sanctioned by the Arizona Game
and Fish Department. It was initiated to provide
appropriate care and custody for tortoises already
in captivity while vigorously discouraging the taking
of tortoises from the wild. Unfortunately, release of
captive tortoises is considered a high risk to existing
populations because of the potential to introduce
disease, disrupt population structure, and mix genetic
stock from different regions.
The Tortoise Adoption Program was established
to aid the welfare of tortoises already in captivity and
insure the preservation of wild tortoises. The program
serves Tucson and its surrounding suburbs but is
dedicated to the well-being and survival of the Desert
Tortoise throughout its range. In general, tortoises
can be adopted from April 1 through September 30
of each year, subject to availability. In Arizona, no one
“owns” a Desert Tortoise, but people may become
“custodians” to insure the welfare and longevity of
those already in captivity. Under Arizona law, one
tortoise per family member may be possessed if the
tortoises are obtained from a captive source and
properly documented. See: http://www.desertmuseum.org/
programs/tap.php
Inspiration
Appreciation of Nature is achieved through posi-
tive experiences. The school Desert Tortoise is an
excellent way to create an atmosphere for the students
where Nature, and particularly the act of discovery in
Nature, is fun. Facts can help foster appreciation but
you do not have to be an expert on tortoises to share
the wonderment of seeing a tortoise with students.
Begin by just letting the animal move around so the
students can watch. Only after the students have fo-
cused on the animal instead of me do I begin sharing
information about it. Another way to convey factual
information is through asking questions. Instead
of telling students that “this type of turtle lives in a
burrow”, ask them, “where do you think this tortoise
makes its home?” Encourage them to ask questions
about what interests them. As an interpreter, your role
is to develop curiosity and help them nd the answer.
Myths, stories, music, art, and literature are also
valuable ways in which people relate to the world
around them and can be extremely efcient in affect-
ing people’s perceptions. Once the class has returned
to the classroom, make an art project, read a book, or
sing a song about tortoises. Have students interpret
their experience however they see t; some may draw
a picture, while others may write a poem or reect on
the experience in a journal entry. Have the students
express their experience with the animals not by being
tested on the material, but by using their creativity to
express what they have learned in some imaginative
way. The students now have a personal experience
that they have manifested without outside inuence.
The experience will surely be positive and hopefully
unforgettable.
Use the coloring sheet (next page) to send kids
home with a conservation message about tortoises.
Other Sources of information:
Arizona Game and Fish Department website:
http://www.azgfd.gov/w_c/deserttortoisemanagement.shtml
Arizona-Sonora Desert Museum website:
www.desertmuseum.org/programs/tap_tortnathistory.php
Tucson Herpetological Society Website:
http://tucsonherpsociety.org/clrbk.html
The Sonoran Desert Tortoise: Natural History, Biology,
and Conservation edited by Thomas R. Van Devender.
Arizona-Sonora Desert Museum Studies in Natural
History; University of Arizona Press, 2006.
After handling
any animal,
children should
wash their
hands. A hand
sanitizer should
be provided if
soap and water
are not easily
accessible.
SONORAN HERPETOLOGIST 26 (4) 2013 89
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