Sunday, February 3, 2013

Recent Dam Collapse is a Serious Problem for our Beaver Colony

Julia surveys the area around the now exposed food cache
Our beaver colony has already had their share of bad luck over the past year, and now they are faced with a new daunting challenge. Late Wednesday night or early Thursday morning, heavy rain fall combined with already high water from a rapid snow melt, burst the dam at Secret Pond. Since Secret Pond is where the beavers’ food cache and main lodge are, this disaster presents a major threat to the colony.

Secret Pond is now down by over 3 feet
Water flows freely out  of the 12 foot gap in the dam
They made a start at repairing the 12 foot gap in the dam, but they appear to in a losing race against time. If they can’t manage to get the water levels up above their stored food supplies before the pond freezes over, those reserves may become inaccessible. As a rule, the beavers’ food reserves or "food cache" is kept below water. They do this so the supplies can be drawn on after the pond freezes over, and food on shore becomes unobtainable.

Repairs begun on the dam are unlikely to be completed any time soon
The entire food cache is now exposed  and  subject to being covered with snow and ice
As far as I know, no beavers were injured by this dam rupture, though I have yet to account one or 2 of the younger beavers. Certainly the scale of the dam collapse was not as large as the one that happened back in June. Back then, their main pond (Sarah’s Pond) was quite large and held at least 20 times the water volume of Secret Pond.4 beavers including the colony’s patriarch were not seen again following the June collapse.

Towing building materials meant for the lodge, Blueberry heads up the  exposed stream channel 
At least 3 feet of water level loss at Secret Pond has left all entrances to the beaver lodge above the water line, which has essentially rendered the lodge uninhabitable as far as the beavers are concerned. As a rule, lodge entrances are kept well below water –this effectively keeps out predators and other creatures that may prey on young beavers or seek to use the lodge as their own den site.
With its entrances now above water, the lodge at Secret Pond is abandoned

Directly beneath the lodge entrances are piles of peeled branches - leftovers from  many dinners
The beavers have now moved into a lodge at an adjacent pond (May Pond). This particular lodge is not in good shape, but its entrances ways are at least submerged. Lodges that beavers use as their winter dwellings are normally plastered over with a thick coat of mud. This winterizing effort, plus any accumulating layers of snow and ice, helps to keep the temperature inside the lodge much warmer than the outside ambient temperature. The beavers perform this task in the fall before the snow flies and the ponds freeze. Now, however, our beavers have been forced into a lodge that has not been prepared in any way for winter.
The beavers have moved into the old  dilapidated lodge at May Pond
The most serious part of this situation is the fact that the beavers may now be effectively isolated from their food supplies. If they are forced to remain at May Pond, and the water there freezes up tight, they will not be able to leave that pond to search for food. Of course, my hope is that they will be able to repair the dam at Secret Pond, and once again gain access to their food reserves and their winterized lodge. This is probably a tall order since during the winter it’s generally more difficult to come up with all of the building materials needed for a large scale building project. However, one thing I've learned from 13 years studying this colony, is that where there’s a beaver, there’s a way.

3 beavers swim together  at May Pond
Of course, I will help them out wherever I can. I can certainly lug food over to May Pond and cut holes in the ice, but repairing Secret Pond is something that only the beavers can do. Whatever way we look at it seems that the beavers will have a difficult period to get through. I’ll be sure to keep close tabs on them.
Blueberry swims by one of last year's kits
Julia comes in close to see if I brought anything
We've had only 3 major dam collapses in the 13 ½ year history of this beaver colony. None of them have happened in the winter.


  1. hi Matt, I was hoping for an update on the beavers. Maybe next week?

  2. 2/11 Update: The beavers gave up on trying to repair the lodge at Secret Pond a few days after the dam collapse. Perhaps they will resume work when the snow is gone and when warmer temperatures prevail. For now, they are still residing at the dilapidated lodge at May Pond. They haven’t been trying to make a new food cache – this is something that beavers rarely do at this time of the year. The beavers are also not attempting to access the food cache at Secret Pond – which is now covered with plenty of snow and ice. However, they have been taking full advantage of the poplar trees that I've been dragging over to them. Certainly, we will continue to help them through this rough patch. I've managed to account for all 7 members of the colony and they all seem healthy.