Beaver dams are amazing constructions of wood, rocks, and mud that dwarf their makers. Apart from termite mounds they may be the tallest structures made by animals other than humans. Unfortunately there aren't many measured records of dam-building champs to rely on. I've heard reports of and found dams that were about 12 feet (about 3.7 meters) tall but I've never seen a study describing dam dimensions and the folks at the Guiness Book of World Records don't seem to be too interested in beaver dams.
The photo with this post shows a tall beaver dam from Algonquin Park in Ontario. Using Norma as a guide (she's 64" tall) and considering she's not standing at the lowest base of the dam I estimate this dam is pretty close to 10 feet tall.
This fall marked the 4th year of my annual fall beaver feeding program. I do this to reduce damage that the beavers do to trees that people don't necessarily want to lose, and to ensure that the beaver colony doesn't eat all their food supply. And the feeding program creates a great opportunity to see the beavers at their food gathering best. Despite the free food, the beavers cut quite a few trees of their own this fall. I'm going to count them and make that into the subject of a future post.
This year I gave the beavers 32 pickup loads of aspen and balsam poplar branches. The photos show one load. It might not seem like much, but the aspen saplings shown in the lake are about 5 m long. That's a lot of branches for me to haul. What's truly amazing though is the removal rate by the beavers. This particular load was dropped off in the late afternoon and it was entirely gone the next morning. Working through the night, the beavers cut up and hauled off the entire load, floating the loot about 300 m from the depot to the food cache they built beside the lodge. Of course all that work takes lots of energy, so the beavers are eating a lot of food as well. What amazes me though is how they take 32 loads like this and make them into one pile at the lodge. The underwater architecture of that pile must be amazing to cram so much into such a small space.
I'm the originator and the biggest fan of the Beaver Boardwalk. Check out the main website at http://beaverboardwalk.ca/index2.html
Click on "comment" at the end of each post if you'd like to leave a comment