More Biology of the Northern Prairie Skink
| By Errol J. Bredin | (Click links for more images.) |
Habitat and Home Range
Skinks tend to "colonize" around an area supplying some form
of surface cover. If one is sighted chances are good there's more
in the immediate area. The size of a colony depends on the amount
of surface cover available. In a purely natural setting this cover
is usually a piece of fallen tree, and the colony quite small,
three or four adults. In other instances, small concentrations
of skinks have been observed inhabiting small excavations under
a thin layer of topsoil. I have found individuals in shallow burrows
under a piece of bark or a decaying tree branch.
It seems that humans have an inherent ability to "litter" the landscape. This highly questionable practice has actually aided Manitoba skinks along with some of our other reptile species. Skinks are quickly drawn to junk scattered about on the surface. If this refuse happens to be flat boards, bits of sheet tin, even cardboard, then skinks are sure to set up housekeeping immediately upon finding it. They seem to prefer man-made surface cover. Some of the largest concentrations of skinks I have found are in litter piles and places where old buildings have been torn down, with boards and roofing tin left lying about. In one instance I routinely checked a single piece of tin 1 m square over a period of four summers and captured, marked, and released 16 skinks that were sheltered under it.
A study area in Carberry Hills.
Skinks, once settled, tend to stay in close proximity to their chosen cover and spend a substantial amount of time under it, lying quietly in small excavations. Over a period of three months I regularly checked a plank 3 m long by .25 m wide. This plank was home to four skinks that I marked for easy identification. Not once did I see one of these skinks out on the surface, but each time I lifted the plank I recaptured all four individuals. There was other suitable cover a meter away, but it was seldom, if ever, used. They do forage for food, but the evidence indicates that they don't venture very far away from their protective cover. In many instances food likely comes to them, in the form of crickets seeking shelter.
During the summer of 1981, I monitored eight colonies of skinks on the CFB Shilo ranges. Individuals were captured, measured, marked, and released. One of the reasons skinks were marked was that, when recaptured, data could be compared and movements determined. In all but two instances there was no noticeable movement, with recaptures occurring within 1.5 m of the point of original capture. However, some individuals do move and can cover considerable distances. As with some humankind, certain skinks succumb to "wanderlust" and set off in search of adventure. Others are forced to leave familiar surroundings when the structure of a colony changes. Perhaps an old male is set upon by a young successor. Territorial fighting is common during the breeding season with the loser forced to relocate. Hatchlings are very active and before reaching sexual maturity seem to travel about in search of a permanent home. Forced relocation can also occur. I noted one instance when, during the winter, an area of scattered litter was cleaned up by military personnel. When skinks emerged from hibernation in the spring they found their familiar cover gone and were forced to move. Late that summer I located one member of this abandoned colony under a piece of plywood 156 m away from the cleaned-up site.
Food
Skinks have a preferred diet, and it includes crickets, grasshoppers, and spiders. Other insects and insect larvae are second choice foods. Ants, a readily available food source, are for the most part abhorred. Cannibalism does occur, with adult skinks preying on their own young.
Watch "Feeding Time"
Protective Adaptation
The Northern Prairie Skink has an interesting protective adaptation. When pursued by a predator, the skink will arch it's long tail and vibrate it vigorously. The attacking animal pounces on this "decoy" and the tail is quickly dropped off, while the skink scurries for cover. This is one reason care must be taken in the handling of skinks, for the tail is easily lost. I have often observed that the tail can be whipped off without being forcefully grabbed. It is amazing to watch as the tail literally leaps and bounds while vibrating vigorously. This nerve action can last ten to fifteen minutes, ample time for the skink to escape while the predator is thoroughly distracted. After losing a tail, the exposed flesh soon heals over and a new tail begins to grow again. A regenerated tail is more complete in young skinks. When an old adult loses a tail the resulting growth is usually quite short and sharply tapered.
Watch "Why NOT to pick up a Prairie Skink!"
Because of their secretive nature and lightning-like speed when disturbed, I don't think any great numbers of skinks are lost annually to predation. However, studies indicate that natural predators include the Western Hognose Snake, hawks, owls, raccoons, skunks, mice, and shrews. Mice appear to be the most serious threat as adult skinks often are found with scaring indicative of attacks by a small mammal. I often find Deer Mice resting under a piece of cover where I've sighted skinks. At times they force the skinks out, or perhaps they kill them outright.
Final Thoughts
Standing high atop a ridge, I have been fortunate enough to witness another sunrise deep within the heart of the Carberry Sandhills. The thick mists have risen and evaporated from over the tamarack bog as I turn and head down the steep slope to the undulating mixed-grass prairie. There's work to do. I currently have 20 reptile-monitoring sites on the CFB Shilo ranges and my little, lifelong friends await my visits.
People ask me: " Why this interest in skinks?" Granted, they seem to have neither a harmful or beneficial effect on overall human affairs or economy. Nevertheless, there may be various unsuspected relationships, and I cannot forget a passage read some time ago: "Everything that lives has something of value to share with you - whenever you are ready for the experience."
Thanks for learning about the Northern Prairie Skink! Bye for now!
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For More on Manitoba's lone lizard visit:
The Save our Skinks website in NatureNorth.com
For more on reptiles in NatureNorth.com check out these articles:
Garter Snakes | Garter Snakes in the Class Room | The Manitoba Herps Atlas
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