Wednesday, January 6, 2016
The Mystery of the Riparian Trees
Suppose you crossed paths with the stick in the picture above. But let's say it was laying in a pile of its bark-less kind well up the bank of a medium-sized creek, only a few feet from a hole horizontal to the flowing water. What is that pattern on the bark-less end? The stick was the snack of a now full beaver. Beavers have a unique method of survival that revolves completely around two elements: Water and Trees. Contrary to popular belief, beavers do not eat fish, nor do they eat wood. Beavers eat a layer of a tree trunk or branch between the bark and wood called cambium. The mystery branch in the picture was a small snack for a beaver, or the beaver was interrupted during its meal. This is evident because there is still un-stripped bark on one end of the stick. So now that we know about this stick, let's talk about beavers. The American Beaver (Castor canadensis) is an enormous, crepuscular and semiaquatic rodent, in fact, the largest rodent in North America. It is characterized by its enormous flapjack-shaped and hairless tail, its large size, and its habit of swimming with sticks in its mouth. In the water, or when it is wet, the beaver's fur looks black and glossy, not at all furry. This makes the animal look somewhat reptilian and it dives with a reverberating smack of its tail on the water's surface when alarmed. It makes this noise to alert other active beavers in the area that danger is approaching. The tail is also used to deal with dirt and mud for construction. A beaver's teeth are brown or yellow, but it is not because they are dirty. The discoloring is found in many rodents and it is apparent because of the extreme calcium build in their teeth, for they have to chew on hard things their whole life. In fact, rodent teeth never stop growing so they need to wear them down on hard materials to chew. Beavers can live in two environments; fast-moving rivers and streams or slow lakes, reservoirs and calm water. These two different environments have two distinct beavers, each with a unique behavior. The beavers that live in quick rivers and streams have to be intelligent builders. They will chop down full-sized trees (See picture gallery below) and sometimes you will find fresh chews with mulch-like chips scattered around the base. These trees are managed and chewed into smaller logs and are used to build a dam and a lodge. A beaver first builds a dam (See picture gallery below) out of sticks and mud. It takes a family of beavers around thirty-three days to build a dam, weaving sticks and securing them with mud placed by their tails. At first look, the beaver dam resembles a pile of brush that washed down the river and then stuck in a narrow spot. But behind the dam, there should be a large, flooded and still pond, called "beaver pond", and has only a little trickle on the other side. It is used to make a calm area where the beavers can swim and work. After beavers leave and the beaver pond gets lower, it makes a grassy, fertile clearing called a "beaver meadow". This dam is held together with mud carried and placed by the beaver's tail. A lodge (See picture gallery) is a formidable dome that's sun-dried and bark-less logs have discolored and reflective affects in the sun. The lodge also has no ground door, instead it has multiple plunge-holes in the floating stick floor that lead to underwater exits. Three generations of beavers live in a beaver lodge. The oldest is the breeding pair, which build the lodge and stay there for years, sometimes until they die. The next generation is made up of two or three young non-breeding beavers from last year's offspring. These beavers help with some lighter work and will leave the next season. The newest generation is the baby beavers or kits. Beaver kits squeak so loudly you can hear them if you walk by the lodge. They need to be supervised in the lodge by another older beaver to protect them from predators. Baby beavers don't exit the lodge during this time, and become a non-breeding lodge resident mostly by the next year.
The beavers that live in slow water are unofficially known as "Bank Beavers" and don't normally chew down full-sized trees. Bank Beavers normally just eat cambium from sticks and saplings. Bank Beavers will use eroded caves, old muskrat holes or just an overhang in the bank for shelter, sometimes digging their own holes. These beavers don't build with sticks, but swim carelessly for their lives and normally never breed. If they decide to breed, they will pair up and move to smaller rivers and streams to build a dam and lodge.
Beavers have a saddening but great history relating to humans. In the 1700's to 1800's, there was a fur craze. In response to this, the Hudson Bay Company sent many men across the United States to trap and hunt beaver. Most were Iroquois trappers, "half-breeds" (an old term for a Native American with a white parent) or poor white men who had to look west for hope. These trappers, or "beaver men" took cruel-looking steel jaw traps and some western Native Americans who joined the Company on the way used spears. These traps were set in a precise and complicated process underwater. Many men died of hypothermia, cougar and bear attacks, as well as many other dangers related to the wilderness. However, large amounts of money were made by turning all of the U.S.'s beavers into coats and top hats. But at what cost? Once the Company realized the one snag in their plan, it was too late. The beavers were gone, "trapped out". All of the trappers went back east or started to farm. The whole fiasco was over. However, many beavers that had retreated silently to their holes in the riverbank started to rebuild. Now, with the help of conservationists and naturalists, beavers have recovered not only in the west, but almost all over the U.S. Today, small amounts of money are obtained by trapping beavers, but regulations have been declared so this tragedy will hopefully never happen again.
Oh, and one more thing. Northern River Otters (Lontra canadensis) are the sworn enemy of beavers. Otters sneak up on the beavers by swimming gracefully through the underwater entrance and stealthily assaulting the young beavers and beaver kits, sometimes even taking adult beavers. Otter tracks are good signs that beavers are in danger. Sometimes, if you are lucky, you may get to watch an otter play in the water or one long slides of snow or mud during the darker hours of the day. Otters are diurnal (active in the day) if not disturbed by human activity. Otter dens look like bank beaver or muskrat holes, and are called "holts". Otter droppings are known as "spraints" and are found in large latrines and are totally made up of fish scales and crayfish parts. Like the beaver, otters too were trapped out, and have made another remarkable comeback due to reintroduction. Both the beaver and the otter are now considered pests to the lumber and the fishing industry.
(A "beaver chew" on a large tree. Note worn ground and wood chips. Also notice the little hemlock sapling in the far left corner. Hemlocks may be gone from these mountains in a few years.)
(A small beaver dam that has recently been through a flood. Note bark, leaves and small twigs that have been unintentionally placed by rushing water. Walking across a beaver dam makes you feel like one of the "beaver men" of old, and makes you marvel at how beavers can build such strong structures.)
(A large beaver lodge in late fall)
(Beaver tracks; front leg tracks in the middle, back leg tracks at the edges.)
(Bank Beaver chews on one of the strongest trees, the Black Locust. This tree is prized for fencing, so someone trying to salvage these trees for later use may get angry with the beavers. These trees aren't full-sized, so they were probably only used as food.)
(A trail cut by extensive use by beavers, otters, snapping turtles and other aquatic and semiaquatic animals. It leads to forested land, so a beaver may use it to access his or her favorite foods.)
One more thing, beavers hate the sound of running water. They can't stand it; likely because it customarily means that their home is in danger of flooding. Happy Trails, Critter Cade