Giving the Side Eye (or Neck)

A Small Turtle in Big Trouble

Naturally, I couldn’t do a season on endangered species without including at least one turtle. This is the Chaco side-necked turtle, Acanthochelys pallidipectoris. Its genus is known as the spiny swamp turtles and contains four species. The other three are all listed as Near Threatened, but the Chaco turtle is considered Endangered. Part of the reason for this is its relatively limited range (though not small enough to qualify based on range size like the dragonflies from last week). Acanthochelys pallidipectoris can only be found in an area called the Gran Chaco, a semi-arid lowland region stretching through parts of Bolivia, Paraguay, and Argentina. Because of the climate patterns in that area, this turtle will bury itself in the mud when streams run dry and it cannot find any natural pools.

Why did I choose to write about this turtle? There are a number of different reasons. Firstly, there are only 327 living turtle species. Since not all of them are Threatened and many that are (such as my favorites the sea turtles) would be considered ‘charismatic megafauna’ that I said I would stay away from this season, my options are somewhat limited. However, that does not mean that the Chaco turtle has no interesting features or stories. As evidenced by the full common name, this species retracts its neck sideways against its shell.

As the above picture shows, this is not a unique feature, but common to an entire taxonomic group of turtles known as the Pleurodira. These turtles are found only in the southern hemisphere and their neck-bending is accompanied by important differences in the structure of their spine and skull compared to the remaining turtles, the Cryptodira, whose necks retract straight backwards (sea turtles belong to that group even though they can no longer fully retract their heads into their shells).

There are several Pleurodiran turtles that are listed as one of the Threatened categories, but this particular species also has a new qualification that we haven’t explored yet: the third criterion for Endangered requires a population size of fewer than 2,500 individuals with continued declines. Those declines also qualify it under the first criterion involving a recent and ongoing decrease in population size. Current estimates for the Chaco side-necked turtle are a population size of less than 1,000 mature individuals.

There are multiple reasons for including the population size criteria for listing a species in one of the Threatened categories. Small total numbers exacerbate other factors. Small random disturbances can have a greater impact. The chances of inbreeding (the presence of genetic disorders caused by the mating of close relatives) increase as the size of the population decreases. These effects can sometimes create a feedback loop and a spiraling decline.

Finally, Acanthochelys pallidipectoris gives us a look at another common threat to species survival that we haven’t explored yet. It suffers from habitat loss and degradation similar to what we have mentioned before with the Witches Cauldron and Venus flytrap. In this case, much of their potential habitat is being converted to areas for grazing cattle or growing soybeans. However, in addition to this, it also suffers losses due to the pet trade, something that is unfortunately too common for at risk wildlife.

While this species is difficult to study in the wild, only being active during the four to six month rainy season, it is estimated to mature in approximately 15 years (the amount for other turtles of similar size, habitat, and life history). This makes it very slow to mature and with the likelihood that reproduction only occurs in years with optimal conditions, any removal of adults to be sold as pets can have a large impact on the species. This is especially true when total population size is so low to begin with.

I do not begrudge anyone their desire for an exotic pet reptile (though there are some choices that are less than wise). As a herpetology fan myself, I understand the appeal. However, please do your due diligence, just like you would for any other pet. There are plenty of pets that are not at risk. Purchasing such an animal likely means that you are also aiding criminal activity, as the import and export of Threatened species is heavily regulated in many countries.

The past two weeks, we’ve looked at the Endangered category. Species classified as such are already in great jeopardy. It is not a classification to be taken lightly. For next week, we are moving to the highest level category of Threatened: Critically Endangered. These are the species that are truly on the brink. Their risk of extinction is extreme and its likelihood high.