Thursday, 21 April 2011

What is the big deal with beavers anyway?

Why are beavers a problem to cottagers?

     If you have beavers near your property, you may have an all too familiar understanding of the term "nuisance beavers," but if beavers have not colonized near your property it may not be so apparent why they could be such a major problem. The most obvious issue with neighbouring beavers is the danger and damage from falling trees; however, the more pressing issue is actually flooding!

Could a beaver dam lead to this?

Cool Beaver Fact #2

The largest beaver dam in the world can be seen from space!

      The phrase busy beavers comes from the fact that beavers are compulsive dam builders. Beavers are always working, cutting down new trees and fixing their dam. Scientists believe that the trigger for this obsession is the sound of running water and possibly even the sight of running water. When loudspeakers playing running water noises are placed near a beaver dam the beavers will continue to gather wood and add to their dam even though it is clearly finished.
     In other blog posts we've briefly described why beaver dams are very important to ecosystems, but why are beaver dams important to beavers? For one thing, a dam creates a reservoir of water that beavers can use as a home. While beavers are good swimmers, they are much worse on land, so a large pond is very preferable for moving around, finding food, and creating new opportunities for food.

      When a number of beaver colonies stay in the same place for a long period of time, beaver dams have the potential to become enormous. Spotted on Google Earth, the largest beaver dam stretches almost a kilometer! Located in Wood Buffalo National Park in Alberta, the dam is 850 m long and has been under construction for over 40 years; however, oddly enough, nobody knew it existed until 2007. The old record holder was a 652 m dam in Three Forks, Montana.

 Behold! The world's largest beaver dam:

The Environmental Role of Beavers

Apart from being Canada’s national symbol and the face of the nickel, the beaver is an ingenious ecosystem engineer that plays a specific role in shaping the unique rural environment that Canadians take pride in: 

1) Keystone Species: The beaver is considered a keystone species, and its ability to beneficially reshape and modify the ecosystem surrounding its habitat renders this species one of the largest contributors to Canada’s aquatic environments. Their removal would upset the balance of the ecosystem, causing collapse. 

2) Ecosystem Functioning: Beavers ensure productive ecosystem functioning, which creates and upholds the natural beauty and species diversity of southern Ontario. 
  •  alterations in hydrology, biogeochemistry, vegetation and ecosystem productivity 
  • beaver damming promotes sediment accumulation, water conservation and provides ideal colonization sites for herbaceous and riparian vegetation 

3) Habitat Provisioning: Habitat modifications by beavers benefit a large number of wildlife species that depend on aquatic, wetland and riparian habitat. 
  • feeding, breeding, wintering and migration habitats for waterbirds, songbirds, wild turkey, etc. 
  • increased prey and forage resources for mammals like mink, muskrats, moose and deer 
  • improvements in water quality and habitat area for multiple fish species

Mutualistic Relationships Between Beavers and Other Species

A) Invertebrates:
-Beaver damming increases invertebrate abundance and changes the invertebrate assemblage in the surrounding habitat by increasing microhabitats
-Typical assemblages of aquatic invertebrates following beaver damming include predatory dragonflies, sludge worms, filtering mussels, midges, water beetles and chironomids
-Typical assemblages of terrestrial invertebrates in a beaver pond include fruit flies, weevils, leaf beetles and bark beetles
-Aquatic invertebrates provide a good food source for fish, while both aquatic and terrestrial invertebrate species provide protein- and calcium-rich food for birds

B) Birds:

-Beaver ponds create important feeding, breeding, wintering and migration habitats for waterfowl and other water bird species (wood ducks in particular for southern Ontario regions)
-The ponds and aquatic vegetation associated with beaver habitats provide courtship areas, nesting cover and travel lanes for birds
-The cutting of trees around beaver habitat during initial colonization opens the forest canopy and improves habitat for edge and woodland species like wild turkey and numerous songbird species
-Dead and decaying trees in flooded beaver ponds may provide nesting and feeding sites for woodpeckers, and when the woodpeckers abandon their nests (because they use a different nest each breeding season) they become used by other birds like flycatchers, tree swallows, tits, wood ducks, owls and kestrels
-Herons, kingfishers, cormorants and egrets use beaver ponds as foraging grounds

C) Mammals:
-Beaver dams increase prey and foraging resources for semi-aquatic mammal species like the North American mink, muskrats, water voles and otters
-Terrestrial mammals like elk, deer and moose benefit from beaver activity through increases in vegetation (bark and branches of felled trees, riparian vegetation)
-Beaver dams also create habitats for mice, gophers, rabbits and hares
-Increases in fish abundance also creates an optimal foraging area for different bear species in the summer

D) Fish:
-Beaver damming improves the habitat for fish species by improving water quality, reducing erosion and reducing seasonal fluctuations in flow
-The increased water levels caused by damming may also improve overwinter fish survival, or create an important winter habitat for fish lacking deep pools, by providing cover and resting habitat and reducing temperature fluctuations
-For salmon, beaver dams maintain the clean gravel required for spawning through reductions in flow rate and decreasing in the silt load in the water
-Fish species including brown trout, sockeye salmon, brook charr, minnows and rainbow trout have been found to be larger in beaver ponds

E) Amphibians and Reptiles:
-Frogs, toads and tailed amphibians (like salamanders) often use the shallow waters of beaver ponds to breed and lay eggs
-This is important because amphibians are becoming increasingly threatened due to habitat degradation, pollution and climate change, and it is crucial that breeding areas be preserved
-Turtles and water snakes may utilize beaver ponds because the habitat provides shallow, slow-moving water with abundant vegetation and soft organic substrates that these species prefer

Wednesday, 20 April 2011

The Role of the Beaver on the Physiochemical Characteristics of Aquatic Ecosystems

There are strong and continuous interactions between hydrology, geomorphology, water chemistry and temperature in aquatic ecosystems, and they are all significant factors that influence aquatic organisms, and can be modified by beaver activity.

A) Hydrological Effects of the Beaver:
-Reduction of stream velocity (slows down the flow rate in streams)
-Decreased peak discharge and stream velocity during a run-off event, thereby reducing the potential for erosion
-Reductions in the sediment-carrying capacity of the stream, which causes sediment accumulation, which can protect areas from erosive perturbations
-Increases in the area of riparian habitat, which act as buffers against aquatic contamination
-Recharged groundwater due to elevated water table
-Enhanced water conservation due to decreased run-off efficiency

B) Water Chemistry:
-Beavers may exert considerable influence on the productivity of fresh waters by altering nutrient levels
-Naiman & Melillo (1984) found that beaver ponds stored approximately 1000 times more nitrogen (N) in sediments, per linear metre of stream channel, than riffle areas and that this was solely a function of the amount of sediment accumulated in the different habitats
-Fallen wood from trees killed by inundation and wood used in dams and lodges represent input sources of organic matter that are important to phosphorus and nitrogen dynamics of the aquatic ecosystem and represent a long-term source of nutrients to the pond water and outflow
-The anaerobic zones (without oxygen) in the sediment interstitial waters of beaver ponds may be enriched in dissolved nutrients, which stimulates increased primary production (e.g. higher algae levels were found in streams that housed beaver dams compared to streams without beavers)
-Beavers may play an important role in modifying water chemistry in regions where inputs of strong acids from atmospheric pollution are relatively high
-Smith et al. (1991) found that pH, acid neutralizing capacity (ANC), dissolved organic carbon (DOC), iron (Fe2+) and manganese (Mn2+) values were elevated, while sulphate (SO42–) and ionic forms of aluminium (Aln+) were decreased following passage of water through a beaver impoundment
-Beaver ponds also act as net annual sinks for inlet nitrate (NO3–) and silica (H4SiO4) and a net annual sources of ammonium ions (NH4+)

C) Water Temperature:
-The role of beaver dams on water temperature are somewhat inconclusive, but some patterns have been identified
-Studies have found that beaver dams in large ponds act as thermal buffers, raising downstream water temperatures slightly, and they also decrease daily fluctuations in water temperature to create a more stable environment

The Loss of Wetlands in Southern Ontario


       Wetland decline is a serious issue in southern Ontario that is resulting in rapid and significant biodiversity loss. Many people are unaware that this issue extends right into the backyards of many Ontario residents. In 2010, Ducks Unlimited Canada (a wetland and wildlife conservation organization) released a report indicating that 72% of southern Ontario's large inland wetlands have been lost or converted to other land uses, and that this loss is continuing at an alarming rate. The decline to the wetland base has been most drastic in southwestern Ontario, parts of eastern Ontario, Niagara and the greater Toronto area, where in some regions the loss is greater than 90%. Kingston is one region in particular that has lost a substantial amount of wetland ecosystem, with an estimated 65% loss by 2002. The year 2002 also marks the loss of 1.4 of the original 2.0 million hectares of wetland habitat that was present in southern Ontario prior to European settlement. However, what is even more concerning is that this loss represents only large inland wetlands greater than 10 hectares in size. If the research investigated the loss of all wetlands in Ontario, the percentage of loss would be even higher.
        Wetlands are a vital part of Ontario’s environmental and economic sustainability. They provide many benefits, such as enhancing water quality, ground water recharge, flood, drought and erosion prevention and mitigating the impacts of climate change. Wetlands are important habitat for wildlife and species at risk, offer ecotourism opportunities and provide important social and cultural benefits to the people of Ontario and to all Canadians. A downloadable version of the Southern Ontario Wetland Conversion Analysis by Ducks Unlimited Canada can be found at

Despite this rapid decline in wetlands, all hope is not lost, and the beaver is one solution to help mitigate the problem. The construction of beaver dams can actually restore and/or create wetlands by expanding the saturated surface area of the riparian zone, which causes the surrounding terrestrial community to be converted into an aquatic community.

How To Humanely Relocate Beavers

The Beaver Baffler:

The beaver baffler is an effective long-term solution for discouraging beavers from using your property, or areas adjacent to your property, for the construction of their dams. This device is made from one or two large-diameter drain pipes (7.5 to 10 cm) that are installed through the dam, with one end in the deep part of the pond and the other downstream, far away from the dam. The water flows through the dam into the downstream region, lowering the water level in the area surrounding the beaver dam. The distance between the dam and the drain outlet is important because beavers are attracted to the sound of running water and are compelled by instinct to dam it up. The farther the distance from the dam, the greater the success in confusing the beaver. Because the drain is under the surface of the water, the beavers are unlikely to discover why they can’t control the water level in the pond and eventually they will become discouraged and move on, leaving behind a small pond. Over time new beavers may move in, but they will not stay long if they can’t increase the depth of the pond. Periodic maintenance of the baffler is required. Installation is sometimes done with the help of local naturalist or hunter groups who have an interest in maintaining ponds as wildlife habitat.

Saturday, 16 April 2011

How To Deal With Beavers That Cause Flooding

The Clemson Beaver Pond Leveler:

The Clemson Beaver Pond Leveler (Figure 1) was developed to meet two goals: 1) The need to suppress the problem of flooding of agricultural and timber lands and 2) To maintain or improve some of the benefits derived from beaver ponds and associated plant communities while preventing extensive flood damage. The Clemson Beaver Pond Leveler device should help reduce flooding, manipulate pond levels and solve road culvert plugging problems. The device consists of perforated PVC pipe that is encased in heavy gauge hog wire. This part is placed upstream of the dam or blocked culvert, in the main run or deepest part of the stream. It is connected to non-perforated sections of PVC pipe which are run through the dam or culvert to a water control structure downstream. It is effective because the beavers cannot detect the sound of flowing water as the pond or culvert drains and therefore they won't try to plug the pipe.

10' section, 10" diameter. PVC pipe
PVC cap for 10" diameter. PVC pipe
10" x 8" PVC pipe reducer coupling
86" sections, 3/4" diameter plastic roll pipe (water pipe), 160 psi grade
1/4" metal couplings for roll pipe
1⁄4" x 2" galvanized eyebolts
1⁄4" galvanized nuts
1⁄4" galvanized washers
16" sections, 8 gauge galvanized wire (medium hardness)
96" sections, 2" x 4" 12 1⁄2 gauge galvanized welded wire
Crab trap clamps (fasteners)
2 lbs

Figure 1. Diagram of the Clemson Beaver Pond Leveler. 

Friday, 15 April 2011

How To Deal With Beavers That Destroy Personal Property

1) Fencing: Trees can be protected by wrapping heavy mesh hardware cloth, sheet metal or a few layers of chicken wire around the base of a tree to a height of one metre, to prevent winter snow chewing. The fence generally does not need to be anchored to the ground, and the bottom can be cut to fit a sloping ground, or to protect prominent roots from chewing. Leaving a few inches of space between the tree and the wire allows for tree trunk growth. Replace as needed with a larger diameter cylinder to allow for trunk expansion.

2) Homemade Repellents:

a) Abrasive Tree Paint (Textual Repellent): It is advisable to make only in small batches of the paint at a time on the day you are going to apply it. Using too much sand will cause the mixture to roll off the tree. Apply paint to bottom three to four feet of tree trunk. For best results, do not paint every tree, leaving some for beaver food. This formula does not work for saplings, so protect them with wire fencing. To reduce the conspicuousness of the repellent, it is usually possible to get the paint tinted to match the colour of the tree if you bring a sample of the tree bark to your local hardware store.

Paint: Exterior Latex (choose a color to match the bark) 
Mason Sand (30 mil or 70 mil) 
Formula Mix 5 oz sand per quart of paint, or 
Mix 20 oz sand per gallon of paint, or 
Mix 140 gm sand per liter of paint
    b) Aversive Taste Repellents: Cayenne Pepper: Vegetable or mineral oil infused with cayenne pepper and then painted on the tree trunks has also been reported as an effective means of preventing beaver chewing.

    Pesky Beavers?!

    Have beavers been trampling on your cottage or your home? Have they been destroying your trees and flower beds? Do you feel compelled to trap...or even shoot them? Don't.

    Yes there are laws and acts in Ontario, British Columbia and other areas of Canada that allow private landowners the right to abolish them, but the downstream effects of killing beavers are disastrous!

    This blog will inform you of the numerous benefits of beavers, the downside of eradicating beavers, major conservation issues related to beavers, and numerous economical and sustainable ways to live harmoniously with beavers! Check back from time to time to learn more about beavers!

    If there are any questions or comments feel free to comment below any blogposts!


    Beavers are Master Builders!

    Beavers are enablers! They provide numerous ecosystem services through dam building - such as altering water and soil chemistry, providing habitat for other organisms and allow sedimentation. This video accurately depicts the beaver's ability to expand ponds and create vast channels to create and sustain habitats.

    An Inside Look into the Life of the Beaver

    This video is a great tool for anyone who wishes to gain more information about the fascinating lifestyle of beavers and the amount of work that is put into dam construction. Beavers truly are Canada's most iconic rodents!

    Cool Beaver Fact #1

    The beaver was once classified as a fish

    While the beaver is certainly an agile swimmer and is at home in the water, it is most definitely not a fish. In fact, there are some reptilian ancestors… and then some amphibian ancestors in between beavers and fish.


    This is a tree of vertebrates and shows which classes have common ancestors. Beavers are mammals and would fall under the category of “Rodents and rabbits” in this tree. To get truly specific, the North American beaver is of the order Rodentia, the family Castoridae and the genus Castor and the species is called canadensis. This means that the North American beaver is a castorid rodent (of which only two species survive today), that we call Castor canadensis. Their closest relatives are squirrels and marmots.

    Regardless of the beaver's true position in the tree of life, in 1760 the College of Physicians and the Faculty of Divinity in Paris declared the beaver to be a fish! The logic behind this classification goes something like this:  fish have scales, beavers have scaly tails, therefore the beaver must be a fish. Though, beaver tails are actually just leathery, not scaly like a fishes scales. The motive for this classification was really so that beavers could be eaten during lent. Meat (but not fish meat) is prohibited during Fridays in Lent, but if beavers were fish it would not be a sin to eat them. Similarly, in the 16th century, the pope declared the largest rodent in the world, the capybara, to also be a fish. During this period, every year 400 tons of capybara was eaten during Lent.

    Lastly, here is a new (possibly?) beaver inspired movie: