Colorado Box Turtle Project
13941 Elmore Road
Longmont, CO 80504
A preliminary report on the status of the ornate box turtle
(Terrapene ornata) in the sandhills of eastern Colorado
Eric Gangloff, Ann-Elizabeth Nash, & Jonathan Scupin
The ornate box turtle (Terrapene ornata) dwells primarily in the grasslands of the Great Plains,
with a range extending across central North America from the Mississippi River basin to the
foothills of the Rocky Mountains. In Colorado, as in Nebraska (Converse et al. 2005), the ornate
box turtle lives in sandhills and prairie ecosystems. Traditionally, the range of the ornate box
turtle extends across the eastern third of the state, from the Platte River in the north to the Front
Range of the Rocky Mountains in the west to the state’s eastern and southern borders with Kansas,
Oklahoma, and New Mexico. Despite laws prohibiting commercial collecting and sale in Colorado,
these activities continue to be common practice. Anecdotal information indicates that this species,
once abundant, is much less common throughout this range. Despite their listing in Appendix II of
the Convention on International Trade of Endangered Species (CITES) of Wild Fauna and Flora,
no comprehensive studies of T. ornata population dynamics or behavior have been conducted in
Colorado to date. Studies of T. ornata in the sandhills of Nebraska indicate that human impact is
directly responsible for declining numbers and recommend that conservation measures be taken
(Converse et al. 2005). Additionally, a 2006 USDA Forest Service report indicates that data on
this species are incomplete and outdated and call for future studies to establish population viability
and conservation needs, claiming that “It is especially important that surveys be conducted in
areas where ornate box turtles were
known to be abundant both recently
and historically, as well as in areas
likely to be affected by human activity
in the future” (Redder et al. 2006).
The Colorado Box Turtle Project will
provide information vital to assessing
the status and conservation needs of
this familiar species.
Our goal for the summer of 2007
was to identify a study site that
contained what appeared to be a viable
population of box turtles and where
we could gain landowner permission
to conduct a study. By mid-June,
a site was identified that met both
criteria. A ranching and farming family
generously gave us free access to their
land – approximately 15.5 km2 of cattle
ranching and mixed farming on the A turtle-eye view of typical habitat and vegtation.
sandhills of eastern Colorado. Dirt roads are used primarily by trucks to access oil and natural gas
wells on the property. The vegetation is both native and non-native, including a variety of grasses,
with significant populations of common ragweed (Ambrosia artemisiifolia), sand sagebrush
(Artemisia filifolia), great plains yucca (Yucca glauca), kochia (Kochia scoparia) and plains
pricklypear (Opuntia polycantha). Trees and standing water are scarce amongst the rolling hills
and friable soil.
Between June 15 and October 7, a group of volunteer researchers located and collected data on 33
live and 7 deceased turtles through visual surveys over an area of approximately 50ha of sandhills,
used only sporadically for cattle grazing. Each turtle was notched using a three-letter code as
found in Somers and Matthews (2006). A variety
of data were collected for each sighting, including
GPS coordinates, mass, carapace and plastron
dimensions, air and ground temperatures, activity,
weather, and shell abnormalities. Additionally,
each turtle was photographed from dorsal and
ventral aspects, as well as in situ. Of the live turtles
found, 16 were adult females, 12 adult males, and
5 juveniles. The mass range was 16g to 442g and
the straight carapace length range was 40.4mm to
128.0mm. Incidentally, GPS data were collected on
sightings of the great plains toad (Bufo cognatus),
western rattlesnake (Crotalus viridis), bullsnake
(Pituophis catenifer), and western hognose
snake (Heterodon nasicus) for future analysis or
Observations Dorsal view of carapace, turtle MNO.
The nearest standing water on the site is overflow from a wind-powered stock tank used for cattle.
The closest turtle found to the water was 113m away, while the vast majority of turtles found
were over 500m from this water source. Home range size estimates conducted on populations of
T. ornata in Iowa, New Mexico, Texas, Wisconsin, Nebraska, and Kansas (Berstein et al. 2007;
Nieuwolt 1996; Blair 1976; Doroff and Keith 1990; Trail 1995; Metcalf and Metcalf 1970) are much
smaller than those necessary to include this standing water source in normal annual activities. Our
findings support Rose’s (1984) assertion that “It is not necessary for a box turtle to have a home
range with a permanent source of surface water.” This is supported by our observations of turtles
drinking from ephemeral rain puddles and turtles consuming succulent plants, such as the fruit
of the plains pricklypear (Opuntia polyacantha). Further studies and observations are needed to
ascertain how often box turtles use these water sources and to what extent they are available.
Another noteworthy finding was that 4 of 5
juveniles (the largest with a straight carapace
length of 62.5mm) emitted a strong musk odor
when handled. There is little literature available
on this behavior and its purpose. Neill (1948)
reports finding an odor in juvenile eastern box
turtles (Terrapene carolina carolina) more
pungent than that of the musk turtle (Sternotherus
odoratus). He postulates that the ability to emit
this odor ends at the same stage in growth when
the plastron hinge is fully developed. Dodd (2001)
conjunctures that musking may serve a social
function and/or as a predator deterrent. Further
Turtle OVW, a musking juvenile.
Figure 1: GPS coordinates of turtle locations overlaid on an aerial photograph of the sandhills.
Turtle NWX soaking and drinking in an ephemeral puddle.
studies and observations are needed to determine
the purpose of musking in juvenile Terrapene
Size and Mass
Data on natural size of these turtles has useful
husbandry applications in terms of creating
normative ratios of size to mass. These data,
such as that presented in the “Straight Carapace
Length/Mass Ratio vs Straight Carapace Length”
graph, allows caretakers of captive animals the
means to assess a turtle’s relative weight and
determine when a turtle is malnourished or obese.
While further data need to be collected to create
an accurate depiction of turtle growth curves,
preliminary data do point to an approximate 0.3
mm/g straight carapace length to mass ratio as
turtles reach maturity.
Turtle JOV beside pricklypear fruit it was
Figure 2: Plot of the
straight carapace length
to mass ratio divided by
straight carapace length.
This has been a successful first year in what will be a long-term study of ornate box turtles. In the
summer of 2008, we hope to receive funding to attach iButtons and radiotransmitters to turtles,
which will provide valuable data about temperature preferences, thermoregulation, micro- and
macrohabitat use, home range size, and water sources. Additionally, observation of day-to-day
box turtle activities, including thread trailing and direct observation, will provide data about
water and food sources, locomotion, travel preferences, and reproduction. These data will be
collected by intensive observations over short periods of time (e.g., watching one turtle for a 24-
hour period) and by long-term tracking. These data will be invaluable in assessing the box turtle’s
status on the eastern plains and sandhills of Colorado and in developing conservation measures,
should any be necessary. This is especially prescient given that the eastern plains of Colorado are
under enormous pressure from human development and all signs indicate that this will increase
in the years to come. The proposed Prairie Falcon Parkway Express (the “Super-Slab” toll road)
would have an enormous impact on Terrapene ornata and other plains-dwelling fauna and flora,
essentially extending the suburban development of the Front Range several hundred miles east.
Beginning in the summer of 2009, we hope to
add an additional element to the study: blood
and DNA sampling. With a veterinarian or
university partnership, these data could be
used to establish population migrations over
time, genetic drift in isolated populations,
displacement of individuals from human
intervention, level of genetic diversity and
hence extinction probability in fragmented
populations, and other information necessary
to understand how a population remains
viable over time. Establishing blood level
norms, like the size to mass ratio discussed
above, has useful applications for those of
us who care for these animals in captivity; Turtle NWX.
current knowledge and methods often indicate
an illness only after it is beyond treatment.
These field observations are labor intensive. This year, we successfully arranged a partnership
with P.S. 1 Charter School, a small urban middle and high school in Denver. A group of 21 students
spent two days in the field, locating turtles and recording observations. Such a large number
of eyes conducting visual surveys increased efficiency greatly. Additionally, such partnerships
promote environmental awareness and instill responsible stewardship attitudes in young people.
We intend for this partnership to expand in the coming years, thus allowing the project to serve the
double purposes of the collection of scientific data and educational outreach.
The current status of T. ornata is unknown in Colorado; anecdotal evidence and trends in other
locations indicate a dire need to conduct studies so that its status, and protection if needed, can
be established. The Colorado Box Turtle Project intends to provide some of these data as well as
spearhead conservation efforts.
We would like to thank John Iverson, PhD, at Earlham College, Mike Jones and Liz Willey at
the University of Massachusetts Amherst, and Stephen Mackessey, PhD, at the University of
Northern Colorado for access to data, allowing us to visit their field sites, feedback on our project,
and enthusiastic support. We also extend gratitude to the eager young scientists at P.S. 1 Charter
School in Denver, Jen O’Connor, Rebecca Taylor, and Joy Gary for their excellent fieldwork. Thank
you to the Sater family for allowing us generous access to their land.
Bernstein, N.P., R.J. Richtsmeier, R.W. Black, B.R Montgomery. 2007. Home Range
and Philopatry in the Ornate Box Turtle, Terrapene ornata ornata, in Iowa. The
American Midland Naturalist 157(1): 162–174.
Blair, W.F. 1976. Some aspects of the biology of the ornate box turtle, Terrapene
ornata. Southwest Naturalist 21: 89-104.
Converse, S.A., J.B. Iverson, and J.A. Savidge. 2005. Demographics of an Ornate Box Turtle
Population Experiencing Minimal Human-Induced Disturbances. Ecological Applications
Doroff, A.M. and L.B. Keith. 1990. Demography and ecology of an ornate box turtle (Terrapene
ornata) population in south-central Wisconsin. Copeia 1990: 387-399.
Dodd, C.K., Jr. 2001. North American Box Turtles: A Natural History. Norman, OK: University of
Oklahoma Press. 256 pp.
Metcalf, E. and A.L. Metcalf. 1970. Observations on ornate box turtles (Terrapene ornata ornata
Agassiz). Transactions of the Kansas Academy of Science 73: 96-117.
Neill, W.T. 1948. Odor of Young Box Turtles. Copeia 1948: 130.
Nieuwolt, P.M. 1996. Movement, activity, and microhabitat selection in the western box turtle,
Terrapene ornata luteola, in New Mexico. Herpetologica 52: 487-495.
Redder, A.J., C.K. Dodd, Jr., and D. Keinath. 2006. Ornate Box Turtle (Terrapene ornata ornata):
a technical conservation assessment. USDA Forest Service, Rocky Mountain Region.
Rose, R.G. 1984. An Ecological Study of Terrapene ornata in Kansas. Unpublished Master’s Thesis,
Emporia State University.
Somers, A.B. and C.E. Matthews. 2006. The Box Turtle Connection: A passageway into the natural
world. University of North Carolina Greensboro. <http://www.uncg.edu/~absomers/
Trail, C.D. 1995. Natural history and habitat use of the ornate box turtle Terrapene ornata ornata
at a mixed-grass prairie in southwest Nebraska. Unpublished Master’s thesis, University of
November 4, 2007.