Reptiles at Risk

Spruce Woods Provincial Park and the Spirit Sands

Posted by Jeff Hathaway on July 28, 2006 at 2:36 PM

We've been operating out of Spruce Woods for the last couple of days, doing programs at local public libraries. This region is one of our major target areas, since it is home to two very cool reptiles, the northern prairie skink and the western hognose snake. Hognose snakes are also found farther west, in Saskatchewan and Alberta (and the eastern hognose snake is found in Ontario, too). The prairie skink, however, is only found around here, in the sandy area known as the Carberry Sand Hills.

This interesting formation is the result of glacial runoff thousands of years ago. As the last glaciers retreated, the meltwater carried vast quantities of sand and gravel with it into the newly created Assiniboine River valley. The sand was carried along all the way to a giant lake, Lake Agassiz, where it was deposited on the lake bottom to create a huge delta. Eventually, the lake shrank away, leaving a large area of sand, which was sculpted by the wind into a landscape of dunes and hills. It is this sandy landscape that the prairie skink and hognose snake depend on, as both creatures burrow into the loose sand to survive.

We took a short hike into an area of the park called the Spirit Sands, to see what is looks like firsthand. Beautiful, to say the least! Also, very hot and dry! More drinking water required, next time! A picture of the area is at http://www.flickr.com/photos/scisnake/199803372/, and we did also catch a glimpse of a prairie skink! See if you can find its striped body in the picture at http://www.flickr.com/photos/scisnake/199803373/

Of course, nothing in nature is static. Bare sand dunes gradually get colonized by hardy plants, usually grasses such as little bluestem. These pioneers help to stabilize the sand, and this allows other plants to take hold. Eventually trees such as trembling aspen get established. This vegetation, which covers the sand and holds it all together with root networks, prevents the prairie skink (and to a lesser extent, the hognose snake) from being able to use the habitat.

This succession of the landscape is a significant reason why prairie skinks are a species at risk, but it's not all nature's fault! The changes humans have brought to the area are accelerating the loss of habitat. Significant areas where skinks used to live have been converted to farmland.

Also, the trees and plants used to be controlled by fires, which would often burn across the dry landscape in the summer. While the hardy grasses would often survive such fires, the trees would not, so large areas of new prairie skink habitat would be created quite regularly. Now, we control such fires, so that they don't threaten people's homes and farms. As a result, there are only small areas remaining that area suitable for the skinks to live, and these are often disconnected from each other.

These small areas are also threatened by an exotic invader- a plant called leafy spurge! This plant quickly forms a dense mat over the sand and renders it unusable for the skinks. At least three areas where skinks used to live have been overtaken by leafy spurge.

Spruce Woods park is using fire in a controlled way to help create more habitat- this is called a 'prescribed burn', but more of these will need to be done in the future, especially on lands outside of the park itself, if we want to have the prairie skink around in Manitoba in the future!

So, what can you do to help the prairie skink? If you live in this area, try to keep patches of bare sand exposed and prevent the spread of aspen trees and especially leafy spurge! You can also put out 'cover boards' for the skinks to hide and nest under. These can be old pieces of lumber or plywood, but logs (especially split ones) also work, as does anything else that will sit on the ground and create a spot for a skink!