Doug Von Gausig (see previous post and comment), who is an accomplished photographer and nature recordist, sent me a video of a patch-nosed snake (Salvadora hexalepsis) excavating a burrow (watch the video). In this video, you can see some fascinating behavior. The snake goes into the burrow, apparently loops its body around some sandy soil, emerges holding on to the soil with a coil of its body, and releases the soil away from the burrow. This is an elegant solution to excavation. I have often wondered how snakes manage to dig burrows without having hands. Now I know.
As I was watching the video, I was reminded of watching Sphecid wasps (genus Ammophila) excavating burrows. A wasp would go into the burrow, apparently use its legs to scrape up some dirt, put the dirt between the coxae of her hind legs, back out of the burrow, fly up into the air for about one meter, and release the dirt, which blew away in the wind as a fine plume. The wasp would do this over and over, making sure that no dirt was piled up at the entrance to the burrow as a tell-tale sign of activity for predators and parasites to notice.
I tried to photograph this activity. I found a wasp that was just starting to dig her nest and set up my camera. After a few of her forays in dropping the dirt, I realized that I had a better camera angle if I moved around to the other side of the burrow. I set up the camera again and waited for the wasp to emerge. She did, and instead of flying back, she flew around on the other side of me and started searching for her burrow. At first I was puzzled, but then I remembered the classic Tinbergen experiments with wasps and pine cones. She was using me as a landmark to find her burrow, and did not realize that the landmark had moved. So she was completely disoriented. Needless to say, I moved back to my original position, and she promptly found her burrow.
But back to the patch-nosed snake. I found it very interested that after emerging, the snake spent some time looking around, apparently watching for potential predators. Digging burrows must be a dangerous activity for snakes. A predatory bird or mammal could sneak up on the snake when its head was inside the burrow and grab it before it had a chance to react.
Watching animals like this is an excellent way of reconnecting with nature. Not only do you get a sense of what their behavior is like, but you also can get a sense of what might be important in their lives. And then you can ask yourself the question, are similar problems important to your life?
I agree that snake watching can be fascinating, but I noticed that many country and suburban folks in northern VA (where I used to live) were horrified of snakes. One of their common experiences was finding the blacksnake demurely looking out of their bluebird box just before fledging time. It usually takes a herpetologist to be philosophical under such circumstances. But one good way to overcome fear of wasps is to build a wasp farm -- as described by Howard Ensign Evans in his book by that name. Harry Homeowner can rejoice in the wasps' predatory feats by counting the caterpillars in the wasp nests, and knowing that his garden is being rid of pests organically and free-of-charge.
Posted by: Chris Wemmer | June 16, 2007 at 08:44 AM