Why does my turtles shell look rusty?

Here in the Fraser Valley, Wildlife Preservation Canada, in association with the Greater Vancouver Zoo, is salvaging western painted turtle eggs from nests at high risk to  form the nucleus of a conservation breeding population. We continue to monitor the area to assess the health of population. But how do we recognise the individual turtles?  We are using three ways of individually identifying turtles. Andrea Gielens, Lead Biologist, explains.

Belly Pattern

Each turtle has a plastron (belly) pattern that is unique! Each and every turtle has this pattern from hatching. While the complexity of stripes within the pattern can get more complex as the turtle ages, the overall shape and distinctive features remain. Can you tell the difference? Sometimes siblings look similar to each other, sometimes not! Sometimes individuals have very distinctive patterns, like our guy named “Skeletor”, from the head starting program.

Pros: Individual and doesn’t change for entire life.

Cons: Hard to ID without a catalogue (ie computer) in the field…and going through so many photos for large populations.

Shell notching

We also notch all the wild turtles that we catch, either at nesting time or during monitoring (trapping) sessions. Each turtle gets a notch pattern on the left side of their shell that is a site code (each site has a different code). This marking allows us to track turtles moving between areas, either moving on their own or because of humans moving them (please don’t move turtles!) The right side has an individual notch, which differentiates turtles at each site. The shell is notched with clippers and a file. The clippings can be used for genetic work. The process is akin to getting an ear pierced, they can feel it, but its minor.

Pros: Individual ID, allows for quick reading in the field, allows for some tracking of animals based on site.

Cons: We can’t use this technique to mark small animals as growth will fill in the notch, damage to shell can make marks unreadable – this is why we backup with photo catalogues.

Pit tagging

These small microchips are the same chips used in your dog or cat. They contain a unique number and can be inserted under the skin. The chips are then scanable in the field. This gives each animal a unique ID that is invisible to the naked eye. Currently we are just using this for our head started released turtles. These turtles are too small for notching so this technique is more useful for them.

Pros: Individual, non-descript. Good for tracking turtles that are removed by poaching or pet trade, good for ID of turtle too young to be notched.

Cons: Need to be implanted in sterile environment and monitored for infection (not for field use), require all field biologists to have a scanner in the field (expensive) and the tags themselves have a cost.

Snapping turtles prefer to inhabit the muddy ponds, lakes and rivers throughout much of the United States. They spend most of their time in the water, but come ashore during June and July to lay their eggs. It is best to avoid contact with these turtles, as they have been known to attack humans. Two species of snapping turtles exist: the common snapping turtle and the alligator snapping turtle.

Skin and Shell Color

The shell of a snapping turtle can be brown, tan or olive green. Young snapping turtles showcase light brown shells. The color of their skin varies and is frequently yellow, brown, rusty orange or slightly red. Factors believed to affect skin color include diet, water quality and soil type. The throat, tail and limbs exhibit the most prominent skin pigmentation. Snapping turtles blend in with the environment. Algae frequently grows on their shell and the skin is usually saturated with mud.

Size Varies

Female common snapping turtles average 9.5 to 14.5 inches in length, with a shell size of 11 inches. Males are slightly larger at 9.5 to 15.5 inches with a shell size of 13.3 inches. Most common snapping turtles weigh between 35 and 45 pounds. They can grow as large as 18.5 inches in length and weigh up to 85 pounds. Freshly-hatched common snapping turtles are the size of a quarter. By 10 years of age, they are 7 inches long. At 25 years of age they average 11 inches in length. The alligator snapping turtle averages 15 to 26 inches in length and weighs between 35 and 150 pounds. Snapping turtles possess small shells, prohibiting them from tucking their head and limbs inside the shell if frightened or threatened.

Impressive Skills and Appearance

Snapping turtles possess powerful jaws that are yellow or cream in color. They do not have teeth, which is why they snap viciously at prey. Their neck is thick and can extend half the length of their body. A snapping turtle’s eyes are located on the side of his head. The eyes exhibit a pattern of black spots, resembling the shape of a cross. Alligator snapping turtles have thick, fleshy eyelashes, which are not found on the common snapping turtle. The alligator snapping turtle’s head is triangular, while the common snapping turtle has an oval-shaped head.

A Solid Build

Snapping turtles have webbed feet. The two front feet showcase five razor sharp nails and the back feet have four nails. In larger turtles, the feet can be the size of human hands. Legs are robust, solid and covered with scaly skin. Tails are long with a saw-like appearance. The shell of the alligator snapping turtle has three distinct ridges, which are most visible in young turtles. Common snapping turtles possess a smoother shell.

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