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A Guide to the Amphibians
and Reptiles of California





Identifying California Turtles

 






California Turtles:




observation link

 
This is not a detailed key to identifying turtles found in California, just a simple guide for someone who wants to identify a turtle by color, pattern, and other physical characteristics as well as by geographical location within the state. You can read more information about each turtle by clicking on the blue name links.

Besides sea turtles, there are only three species of native California turtles, and four non-natives which have established themselves with breeding populations in the state, mostly around populated areas.

A turtle found in the wild in California may not be a native turtle or even one of the established non-natives seen here. In populated areas, especially in ponds and lakes in city parks, you will often find exotic turtles which have been released by irresponsible pet owners. These turtles may be similar in appearance to the turtles shown here. In order to identify them you will need a comprehensive guide to turtles of the world, since these pet turtles can originate from just about anywhere.

When identifying a turtle here, it is good idea to start by looking at the California Turtles Range Maps to see which turtles occur in the area where the turtle was found. To compare the general appearance of all of the established California turtles, you can look at the California Turtles Photo Index. You can also start by looking at a few basic field marks that are found on some California turtles.

If you cannot find a turtle here, you can also look at our page of Escaped Pets which lists some common pet herps which have been reported to me.
A few diagnostic field marks to look for

Large legs shaped like flippers, with no toes.

turtle

Sea Turtles
Red stripe on head.
Rear of shell serrated.

turtle

Red-eared Slider
Yellow stripes on head.
Red coloring on shell.

turtle

Western Painted Turtle
Large size, jagged shell
barely covering body

turtle

Snapping Turtle
LInes radiating on
shell scales

turtle

Pacific Pond Turtle

Smooth Flat Shell


turtle

Spiny Softshell
Long thin snout


turtle

Spiny Softshell
HIgh domed shell with prominent growh lines.

turtle

Desert Tortoise



Most Commonly-seen Freshwater Turtles in California

There are very few species of turtles found in California, so if you see one at the edge of a pond or stream in the majority of the state, it is almost always one of the following three species. From a distance, these three species all look pretty much the same, with a fairly low, smooth shell with no keel along the top, that often appears a solid dark color when seen at a distance.

If you can get a good look at the head, that should be all you need to do to differentiate them, but there are some characteristics of the shells which can help also.


Red-eared Slider
Trachemys scripta elegans

(Alien Species)
Western Painted Turtle
Chrysemys picta bellii
(Alien Species)
Pacific Pond Turtle
Actinemys marmorata
turtle

turtle pond turtle
turtle turtle
turtle turtle turtle
Red stripes behind the eyes will identify this turtle. Yellow stripes on the head with no red will identify this turtle. Mottled dark markings on the head without stripes will identify this turtle.
turtle turtle turtle
Rear edge of shell is serrated, not marked with red. Rear edge of shell is smooth, not serrated, and usually marked with red. Rear edge of shell is smooth, not serrated, not marked with red.
turtle turtle turtle
Shell usually has a network of yellow lines, though often they are not visible.
There is no red coloring on the shell or plastron.
The front edge of the shields are bordered with red or yellow. Red is usually seen on the underside and edges of the shell. A pattern of spots or lines radiates from the centers of the scutes on the shell.
There is no red coloring on the shell or plastron.
turtle turtle turtle
The plastron has no red. The plastron is red with a large dark marking in the center. The plastron has no red.
map map map
Red: Distribution in California
of alien Red-eared Slider
Red: Distribution in California
of alien Western Painted Turtle
Red: Distribution in California
of Pacific Pond Turtle
(Click on maps for a larger view)

The location in California where you see a turtle can also help to identify it, since most species have a limited distribution in the state, but beware that the non-native turtles can show up near almost any water source, including areas not shown on these maps, especially near populated areas.

Take Care Distinguishing Between old Red-eared Sliders and Western Pond Turtles
turtle turtle turtle
Melanistic adult Red-eared slider - Trachemys scripta elegans, (without red on the head) Riverside County. © Bob Parkard

Introduced melanistic sliders and old sliders whose red "ears" have faded, are often difficult to distinguish from the California native Pacific Pond Turtles - Actinemys marmorata, especially at a distance in the field, and even in hand. According to Bob Packard, with the Western Riverside County MSHCP Biological Monitoring Program, they confirm the identification based on the presence of large inguinal and axillary scutes on the sliders, which are absent on the pond turtles, and by an interesting behavioral clue: the majority of sliders tend to be aggressive, biting readily, while pond turtles are far more reluctant to bite. Of course, to use either of these identification clues, you need to have the turtle in hand, so take caution when identifying a turtle at a distance that has no red on the sides of the head.
red-eared slider
 
Red-eared Slider
A useful way to differentiate Pacific Pond Turtles from Red-eared Sliders, according to wildlife biologist Brandon Stidum, "...is to look at the marginal scutes 8-12 (...the scutes above the tail, or back scutes). Sliders have bifid or slightly forked scutes, where Western Pond Turtles do not; theirs are all smooth and do not split (except for traumatic injuries, but it’s usually only one or a few, not all scutes). The forking in the tail gives red-eared sliders the appearance that the tail is serrated or split in appearance.  While looking for the presence and size of inguinal and axillary scutes is the best way to differentiate between the 2 once you have them in hand, a good way to do it from a distance is to look at the back scutes of the turtles." 




These next four turtles should be fairly easy to differentiate since they are all significantly distinct in appearance, range, habitat, or behavior from any other established California turtle.


Snapping Turtle - Chelydra serpentina (Alien Species)

This non-native turtle can be identified by its heavily serrated shell, massive head, tail with a sawtoothed crest, and its large shell which looks like it is too small for the body. This turtle is rarely seen since it does not usually bask outside the water, and its range is not widespread. The map shows some general locations where this turtle has been seen, but probably not all of them.

snapping turtle snapping turtle head snapper
Heavily serrated shell - adult Massive head without strong colored stripes or dark mottling - adult
 
Heavily serrated shell - juvenile Massive head without strong colored stripes or dark mottling - juvenile
 
map
Red: Alien Snapping Turtles have been found in these locations in California, and may be found elsewhere



Desert Mud Turtle - Kinosternon sonoriense sonoriense   (No longer found in California)

This small native turtle (formerly named the Sonora Mud Turtle) was once found along the Colorado River, but after the river was significantly altered by agriculture and dams, it has not been seen in the area and can be considered either extinct or at best extremely rare in the state.

It can be identified by its small size, its elongated domed carapace, its mottled head, and its range. There are no other turtles with a similar appearance in its area. A plastron with 11 scutes and two hinges are also unique among similar California turtles which have 12 scutes on an unhinged plastron.

turtle turtle turtle
Elongated domed shell Mottled head with nipple-like projections on the throat. Hinged plastron with 11 scutes.
map
Red: Historic California distribution of Desert Mud Turtles



Texas Spiny Softshell - Apalone spiniera emoryi  (Alien Species)

The non-native Texas Spiny Softshell has been introduced and established along the Colorado River and the Imperial Valley, and in San Diego County. It has also been reported from other scattered locations, but most likely it has not been established in these areas. This turtle can be easily identified by its very flat, smooth, shell, it's long snout, and its range.

     
turtle turtle turtle
Flat, olive-gray shell with no visible plates or scutes Long thin snout with nostrils at the end
map
Red: Caifornia distribution of alien Texas Spiny Softshells



Mohave Desert Tortoise - Gopherus agassizii

This native tortoise is limited to hot dry desert regions. It can be identified by its terrestrial lifestyle, its large unwebbed limbs, its high domed shell with prominent growth lines on the scutes, its unwebbed toes and elephant-like skin, and by its occuance in the desert away from water sources. Nevertheless, it was once a popular pet and released animals can be found anywhere. (I saw one at a golf course in San Francisco.)


turtle turtle turtle
  Head is unmarked, with large scales.  
turtle turtle turtle
Some adults and juveniles have light patches on the scutes. High domed shell. Growth lines on the scutes.
map
Red: Historic California distribution of Mohave Desert Tortoise





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