Turtles are among the most recognizable and iconic of animals. Any animal with a shell and a backbone is a turtle whether they are called turtles, tortoises, or terrapins. In fact, terrapin is an Algonquian Native American name for turtle. Worldwide there are 356 turtle species on all continents except for Antarctica. The United States has more species than any other country with about 62 currently recognized. Mexico is in second place with 49 species, making North America a global hotspot for turtle biodiversity, especially in the southeastern United States. Unfortunately, turtles are now the most imperiled major group of vertebrates (animals with backbones) with about 60% of modern turtles already extinct or threatened. Reasons for their declining status include habitat destruction and overexploitation for the pet trade and as food. Turtles play important ecological roles in their environments that are diminished as their populations decline. I have been studying turtles worldwide for over 35 years and that research continues. Due to the longevity of many turtle species, long-term studies are necessary to document changes in populations
Background & Importance
Resource managers are concerned about the declining status of many of the world’s turtle species, especially those that are listed as threatened or endangered under the Endangered Species Act. In addition, many species are data deficient: we simply don’t know enough about their biology or abundance to effectively manage turtle populations. Research conducted by U.S. Geological Survey scientists provides resource managers with information that allows them to make knowledgeable decisions that affect conservation and management of turtles.
General Methods
Field techniques vary according to the objectives of each project. Generally, turtles are captured in the field, and marked with unique and permanent notches on their shell that allow researchers to identify individuals at subsequent captures to measure growth, movements, etc. Individual turtles are measured, weighed and sex is determined by examining shell shape and tail size. In some studies, a small sample of turtles are outfitted with radio transmitters that allow scientists to find them on subsequent visits to the field site. In other studies, adult females are X-rayed to determine clutch size, clutch frequency and egg width to determine reproductive potential. Previous published research by the Principal Investigator determined that this technique poses minimal risk to females and embryos. Small blood samples are occasionally taken to obtain DNA used to compare genetic differences between populations. Detailed measurements and DNA samples are used to determine the taxonomic status of poorly-studied species. To date the Principal Investigator has discovered and described four new species of turtles: one in southern Japan (Ryukyu yellow-margined box turtle) and three in the United States (Escambia map turtle, Pascagoula map turtle, Pearl River map turtle).
Important Results
This research summary does not include projects on desert tortoises or western pond turtles. Those species are covered on separate web pages. The Principal Investigator started turtle research in the eastern United States in 1980. Highlights of the research program are given under regional subheadings below:
Pennsylvania – Dr. Carl Ernst, formerly of George Mason University, started research on the ecology of a community of six species of turtles in Lancaster County, Pennsylvania in 1965. Collaboration with Dr. Ernst lead to the publication of several papers on the growth of wood turtles and bog turtles and a long-term study of overwintering behavior in hatchling turtles. The latter study demonstrated that some turtle species hibernate in their nest after emerging from the egg while others emerge the same year as the nest was constructed. Some species do both depending on seasonal precipitation.
Alabama – The Principal Investigator has long been interested in the diversity of map turtles in the southeastern United States. Fourteen species are currently recognized from the Apalachicola River of Florida to the Guadalupe River of Texas. Early research resulted in the description of two new species in the Escambia and Pascagoula Rivers of Alabama and Mississippi. In 2009 another species was described from the Pearl River of Mississippi and Louisiana. More recently, a hybrid swarm of Barbour’s map turtles and Escambia Map turtles was identified using DNA analysis in the Choctawhatchee and Pea Rivers of Alabama and Florida.
Arizona – USGS scientists are working with Montezuma Castle National Monument to study the Sonora mud turtle population at Montezuma Well, a large natural spring in central Arizona. Sonora mud turtles are found in Arizona, New Mexico and Mexico. They disappeared from California in the 1960s likely from habitat modification due to the effects of river regulation from dams. Montezuma Well was a popular site for releasing unwanted pet red-eared slider turtles. USGS scientists removed all the non-native turtle species as part of an experiment to see if the population of Sonora mud turtles would benefit by removing competitor species. That research is ongoing and has resulted in several publications. It is one of only a few examples where invasive species were completely removed from inside an area administered by the National Park Service.
South Carolina – A great deal of research has been concentrated on the yellow-bellied slider turtle, a common species throughout the southeastern United States. Additional research is focused on the diamond-backed terrapin, the only turtle in the world that spends its entire life in brackish tidal marshes at the interface of freshwater and marine environments. Diamond-backed terrapins are found in the United States, from Cape Cod, Massachusetts, to Corpus Christi, Texas, with an isolated population in Bermuda. The Principal Investigator is a key partner in the longest running study in the world, now in its 35th year at Kiawah Island, South Carolina. Terrapins have decreased throughout their range, and a major cause of the decline is drowning in commercial and recreational crab traps. Terrapins were once the most economically important reptile in the world due to their popularity as gourmet food in the late 1800s and early 1900s. Modern threats to their continued survival also include habitat modification and destruction.
New Mexico – In collaboration with the New Mexico Department of Game and Fish, the Principal Investigator is monitoring the reproductive biology of turtles in the Rio Grande and the Pecos rivers since 2012. That research is providing basic information on poorly-studied species, especially the Rio Grande cooter.
Morocco – In 2008, the Principal Investigator received a Fulbright scholarship to conduct research in Morocco. During that time he trained faculty and students at Cady Ayaad University in Marrakech in basic techniques for turtle research resulting in publications and ongoing collaboration. Students subsequently received advanced degrees as a result of their research.
Japan – In 2014, the Principal Investigator was invited to be the Keynote speaker at the second Japanese Freshwater Turtle Symposium in Kobe, Japan. The invitation was a result of his expertise with the biology of slider turtles that are an invasive species in Japan and a perceived threat to the survival of several native Japanese turtles. Collaboration is ongoing and publications are resulting. After the visit to Japan, his collaborators came to the United States to film a movie that included the Principal Investigator and his research on turtles in Arizona and California that later aired in Japan. The Principal Investigator has a long history of research on Asian turtles.
Galápagos – Because of the Principal Investigator’s expertise with turtles and tortoises, in 2012, he was invited by the Galápagos Conservancy to attend a workshop in the Galápagos to develop a ten year strategy for restoration and repatriation of Galápagos tortoises to all islands in the archipelago.
Below are other science projects associated with this project.
The Gemini Solar Project
Below are publications associated with this project.
Graptemys pearlensis Ennen, Lovich, Kreiser, Selman, and Qualls 2010 – Pearl River Map Turtle
Interdrainage morphological and genetic differentiation in the Escambia Map Turtle, Graptemys ernsti
Using climate, energy, and spatial-based hypotheses to interpret macroecological patterns of North America chelonians
A morphological review of subspecies of the Asian box turtle, Cuora amboinensis (Testudines, Geomydidae)
Relationships of maternal body size and morphology with egg and clutch size in the diamondback terrapin, Malaclemys terrapin (Testudines: Emydidae)
Interanal seam loss in Asian turtles of the Cuora flavomarginata complex (Testudines, Geoemydidae)
Intersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles, Graptemys oculifera and Graptemys flavimaculata
Hybridization of two megacephalic map turtles (testudines: emydidae: Graptemys) in the Choctawhatchee River drainage of Alabama and Florida
A 21-year study of seasonal and interspecific variation of hatchling emergence in a nearctic freshwater turtle community: to overwinter or not to overwinter?
Graptemys gibbonsi Lovich and McCoy -- Pascagoula Map Turtle
Traditional cultural use as a tool for inferring biogeography and provenance: a case study involving painted turtles (Chrysemys picta) and Hopi Native American culture in Arizona, USA
Clinal variation or validation of a subspecies? A case study of the Graptemys nigrinoda complex (Testudines: Emydidae)
Below are partners associated with this project.
- Overview
Turtles are among the most recognizable and iconic of animals. Any animal with a shell and a backbone is a turtle whether they are called turtles, tortoises, or terrapins. In fact, terrapin is an Algonquian Native American name for turtle. Worldwide there are 356 turtle species on all continents except for Antarctica. The United States has more species than any other country with about 62 currently recognized. Mexico is in second place with 49 species, making North America a global hotspot for turtle biodiversity, especially in the southeastern United States. Unfortunately, turtles are now the most imperiled major group of vertebrates (animals with backbones) with about 60% of modern turtles already extinct or threatened. Reasons for their declining status include habitat destruction and overexploitation for the pet trade and as food. Turtles play important ecological roles in their environments that are diminished as their populations decline. I have been studying turtles worldwide for over 35 years and that research continues. Due to the longevity of many turtle species, long-term studies are necessary to document changes in populations
Background & Importance
Resource managers are concerned about the declining status of many of the world’s turtle species, especially those that are listed as threatened or endangered under the Endangered Species Act. In addition, many species are data deficient: we simply don’t know enough about their biology or abundance to effectively manage turtle populations. Research conducted by U.S. Geological Survey scientists provides resource managers with information that allows them to make knowledgeable decisions that affect conservation and management of turtles.
Terrapin (Credit: Jeff Lovich, USGS. Public domain.) General Methods
Field techniques vary according to the objectives of each project. Generally, turtles are captured in the field, and marked with unique and permanent notches on their shell that allow researchers to identify individuals at subsequent captures to measure growth, movements, etc. Individual turtles are measured, weighed and sex is determined by examining shell shape and tail size. In some studies, a small sample of turtles are outfitted with radio transmitters that allow scientists to find them on subsequent visits to the field site. In other studies, adult females are X-rayed to determine clutch size, clutch frequency and egg width to determine reproductive potential. Previous published research by the Principal Investigator determined that this technique poses minimal risk to females and embryos. Small blood samples are occasionally taken to obtain DNA used to compare genetic differences between populations. Detailed measurements and DNA samples are used to determine the taxonomic status of poorly-studied species. To date the Principal Investigator has discovered and described four new species of turtles: one in southern Japan (Ryukyu yellow-margined box turtle) and three in the United States (Escambia map turtle, Pascagoula map turtle, Pearl River map turtle).
Important Results
This research summary does not include projects on desert tortoises or western pond turtles. Those species are covered on separate web pages. The Principal Investigator started turtle research in the eastern United States in 1980. Highlights of the research program are given under regional subheadings below:
Pennsylvania – Dr. Carl Ernst, formerly of George Mason University, started research on the ecology of a community of six species of turtles in Lancaster County, Pennsylvania in 1965. Collaboration with Dr. Ernst lead to the publication of several papers on the growth of wood turtles and bog turtles and a long-term study of overwintering behavior in hatchling turtles. The latter study demonstrated that some turtle species hibernate in their nest after emerging from the egg while others emerge the same year as the nest was constructed. Some species do both depending on seasonal precipitation.
Partially submerged Moroccan turtle. (Credit: Jeff Lovich, USGS. Public domain.) Alabama – The Principal Investigator has long been interested in the diversity of map turtles in the southeastern United States. Fourteen species are currently recognized from the Apalachicola River of Florida to the Guadalupe River of Texas. Early research resulted in the description of two new species in the Escambia and Pascagoula Rivers of Alabama and Mississippi. In 2009 another species was described from the Pearl River of Mississippi and Louisiana. More recently, a hybrid swarm of Barbour’s map turtles and Escambia Map turtles was identified using DNA analysis in the Choctawhatchee and Pea Rivers of Alabama and Florida.
Arizona – USGS scientists are working with Montezuma Castle National Monument to study the Sonora mud turtle population at Montezuma Well, a large natural spring in central Arizona. Sonora mud turtles are found in Arizona, New Mexico and Mexico. They disappeared from California in the 1960s likely from habitat modification due to the effects of river regulation from dams. Montezuma Well was a popular site for releasing unwanted pet red-eared slider turtles. USGS scientists removed all the non-native turtle species as part of an experiment to see if the population of Sonora mud turtles would benefit by removing competitor species. That research is ongoing and has resulted in several publications. It is one of only a few examples where invasive species were completely removed from inside an area administered by the National Park Service.
South Carolina – A great deal of research has been concentrated on the yellow-bellied slider turtle, a common species throughout the southeastern United States. Additional research is focused on the diamond-backed terrapin, the only turtle in the world that spends its entire life in brackish tidal marshes at the interface of freshwater and marine environments. Diamond-backed terrapins are found in the United States, from Cape Cod, Massachusetts, to Corpus Christi, Texas, with an isolated population in Bermuda. The Principal Investigator is a key partner in the longest running study in the world, now in its 35th year at Kiawah Island, South Carolina. Terrapins have decreased throughout their range, and a major cause of the decline is drowning in commercial and recreational crab traps. Terrapins were once the most economically important reptile in the world due to their popularity as gourmet food in the late 1800s and early 1900s. Modern threats to their continued survival also include habitat modification and destruction.
New Mexico – In collaboration with the New Mexico Department of Game and Fish, the Principal Investigator is monitoring the reproductive biology of turtles in the Rio Grande and the Pecos rivers since 2012. That research is providing basic information on poorly-studied species, especially the Rio Grande cooter.
Morocco – In 2008, the Principal Investigator received a Fulbright scholarship to conduct research in Morocco. During that time he trained faculty and students at Cady Ayaad University in Marrakech in basic techniques for turtle research resulting in publications and ongoing collaboration. Students subsequently received advanced degrees as a result of their research.
Jeff Lovich's Japanese collaborators in Kobe, Japan.(Credit: Jeff Lovich, USGS. Public domain.) Japan – In 2014, the Principal Investigator was invited to be the Keynote speaker at the second Japanese Freshwater Turtle Symposium in Kobe, Japan. The invitation was a result of his expertise with the biology of slider turtles that are an invasive species in Japan and a perceived threat to the survival of several native Japanese turtles. Collaboration is ongoing and publications are resulting. After the visit to Japan, his collaborators came to the United States to film a movie that included the Principal Investigator and his research on turtles in Arizona and California that later aired in Japan. The Principal Investigator has a long history of research on Asian turtles.
Galápagos – Because of the Principal Investigator’s expertise with turtles and tortoises, in 2012, he was invited by the Galápagos Conservancy to attend a workshop in the Galápagos to develop a ten year strategy for restoration and repatriation of Galápagos tortoises to all islands in the archipelago.
- Science
Below are other science projects associated with this project.
The Gemini Solar Project
The United States is developing renewable energy resources, especially solar, at a rapid rate. Although renewable energy development is widely perceived by the public as “green technology,” construction, operation, maintenance, and eventual decommissioning of facilities all have known and potential negative impacts to natural resources, including plant communities and wildlife. This is especially... - Publications
Below are publications associated with this project.
Filter Total Items: 18Graptemys pearlensis Ennen, Lovich, Kreiser, Selman, and Qualls 2010 – Pearl River Map Turtle
The Pearl River Map Turtle, Graptemys pearlensis (Family Emydidae), is a moderate-sized aquatic turtle endemic to the Pearl River drainage of Louisiana and Mississippi. This taxon has long been a cryptic species, as it was considered part of G. pulchra before 1992 and part of G. gibbonsi until 2010. Graptemys pearlensis exhibits sexual dimorphism, with adult females being considerably larger (caraAuthorsJoshua R. Ennen, Jeffrey E. Lovich, Robert L. JonesInterdrainage morphological and genetic differentiation in the Escambia Map Turtle, Graptemys ernsti
Graptemys ernsti, the Escambia Map Turtle, inhabits the Escambia/Conecuh River, the adjacent Yellow River, and the Pea River further to the east, all of which have been distinct drainage systems since the Pleistocene. We used continuous and meristic morphological and genetic data to compare populations of G. ernsti and found evidence of differences among the three drainages. Frequency of occurrencAuthorsJoshua R. Ennen, James Godwin, Jeffrey E. Lovich, Brian R. Kreiser, Brian Folt, Sarah HazardUsing climate, energy, and spatial-based hypotheses to interpret macroecological patterns of North America chelonians
Our study investigates how factors, such as latitude, productivity, and several environmental variables, influence contemporary patterns of the species richness in North American turtles. In particular, we test several hypotheses explaining broad-scale species richness patterns on several species richness data sets: (i) total turtles, (ii) freshwater turtles only, (iii) aquatic turtles, (iv) terreAuthorsJoshua R. Ennen, Mickey Agha, Wilfredo A. Matamoros, Sarah C. Hazzard, Jeffrey E. LovichA morphological review of subspecies of the Asian box turtle, Cuora amboinensis (Testudines, Geomydidae)
The turtle Cuora amboinensis has an extensive distribution covering most of southern mainland Asia, Indonesia, and extending to the Philippine Islands. Unlike many species, C. amboinensis occurs on both sides of Wallace's Line separating Asian and Australian flora and fauna. Four subspecies are currently recognized; Cuora a. kamaroma (southern continental Asia, Java and the northern Philippines [iAuthorsCarl H. Ernst, Arndt F. Laemmerzahl, Jeffrey E. LovichRelationships of maternal body size and morphology with egg and clutch size in the diamondback terrapin, Malaclemys terrapin (Testudines: Emydidae)
Because resources are finite, female animals face trade-offs between the size and number of offspring they are able to produce during a single reproductive event. Optimal egg size (OES) theory predicts that any increase in resources allocated to reproduction should increase clutch size with minimal effects on egg size. Variations of OES predict that egg size should be optimized, although not necesAuthorsMaximilian M. Kern, Jacquelyn C. Guzy, Jeffrey E. Lovich, J. Whitfield Gibbons, Michael E. DorcasInteranal seam loss in Asian turtles of the Cuora flavomarginata complex (Testudines, Geoemydidae)
The taxonomy of Asian box turtles of the genus Cuora is complicated by the description of numerous valid and invalid taxa over the last several decades. However, some characteristics used to differentiate species are questionable. Members of the C. flavomarginata complex are defined by some, but not all, taxonomists as having reduced interanal seam lengths relative to other species. We examined thAuthorsCarl H. Ernst, Jeffrey E. LovichIntersexual allometry differences and ontogenetic shifts of coloration patterns in two aquatic turtles, Graptemys oculifera and Graptemys flavimaculata
Coloration can play critical roles in a species' biology. The allometry of color patterns may be useful for elucidating the evolutionary mechanisms responsible for shaping the traits. We measured characteristics relating to eight aspects of color patterns from Graptemys oculifera and G. flavimaculata to investigate the allometric differences among male, female, and unsexed juvenile specimens. AddiAuthorsJoshua R. Ennen, Peter V. Lindeman, Jeffrey E. LovichHybridization of two megacephalic map turtles (testudines: emydidae: Graptemys) in the Choctawhatchee River drainage of Alabama and Florida
Map turtles of the genus Graptemys are highly aquatic and rarely undergo terrestrial movements, and limited dispersal among drainages has been hypothesized to drive drainage-specific endemism and high species richness of this group in the southeastern United States. Until recently, two members of the megacephalic “pulchra clade,” Graptemys barbouri andGraptemys ernsti, were presumed to be allopatrAuthorsJames Godwin, Jeffrey E. Lovich, Joshua R. Ennen, Brian R. Kreiser, Brian Folt, Chris LechowiczA 21-year study of seasonal and interspecific variation of hatchling emergence in a nearctic freshwater turtle community: to overwinter or not to overwinter?
Hatchling emergence patterns were studied in a community of six species of freshwater turtles in Lancaster County, Pennsylvania, U.S.A. including: Chelydra serpentina, Chrysemys picta, Clemmys guttata, Glyptemys insculpta, G. muhlenbergii, and Sternotherus odoratus. Data were collected every year from 1965 to 1985 on estimated date of emergence, carapace length, April – May precipitation, August –AuthorsJeffrey E. Lovich, Carl H. Ernst, Evelyn M. Ernst, Julia L. RileyGraptemys gibbonsi Lovich and McCoy -- Pascagoula Map Turtle
DEFINITION. The Pascagoula Map Turtle, Graptemys gibbonsi, is a large riverine species that exhibits pronounced sexual dimorphism, where females attain a maximum carapace length (CL) of 295 mm and males a maximum of 141 mm (Lovich et al. 2009). Mean adult female CL (248 mm) can be well over twice the mean CL of adult males (104 mm; Gibbons and Lovich 1990, Lovich et al. 2009). In addition, femalesAuthorsJeffrey E. Lovich, Joshua R. EnnenTraditional cultural use as a tool for inferring biogeography and provenance: a case study involving painted turtles (Chrysemys picta) and Hopi Native American culture in Arizona, USA
Inferring the natural distribution and native status of organisms is complicated by the role of ancient and modern humans in utilization and translocation. Archaeological data and traditional cultural use provide tools for resolving these issues. Although the painted turtle (Chrysemys picta) has a transcontinental range in the United States, populations in the Desert Southwest are scattered and isAuthorsJeffrey E. Lovich, Charles T. LaRue, Charles A. Drost, Terence R. ArundelClinal variation or validation of a subspecies? A case study of the Graptemys nigrinoda complex (Testudines: Emydidae)
Widely distributed species often display intraspecific morphological variation due to the abiotic and biotic gradients experienced across their ranges. Historically, in many vertebrate taxa, such as birds and reptiles, these morphological differences within a species were used to delimit subspecies. Graptemys nigrinoda is an aquatic turtle species endemic to the Mobile Bay Basin. Colour pattern anAuthorsJoshua R. Ennen, Marley E. Kalis, Adam L. Patterson, Brian R. Kreiser, Jeffrey E. Lovich, James Godwin, Carl P. Qualls - Partners
Below are partners associated with this project.