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.
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.
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.
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.