Beavers are the kings of the North American and Eurasian semi-aquatic rodents. Beavers weigh over 60 pounds once they are full grown and are rarely messed with by other animals. Beavers construct dams out of logs, trees, leaves and mud that are very effective at stopping up water flow in a small stream or pond. Their dens are a part of this dam and can only be accessed by underwater entrances. Beavers live in family units, much like a human family and there will be several family units in a single area. Beavers are not dangerous creatures, but they can be territorial of their dam, their dens and their young.
Beavers are not usually considered nuisances because they are essential parts of our ecosystem. While building dams and felling trees may be annoying to us, this is an important function for new growth in wooded areas and water flow for aquatic life. However, it is because of these traits, that they are considered pests. Beavers cut down a lot of trees for food and for their dams which can make your property unattractive and cost you money.
Beavers can also disrupt the flow of lakes, rivers, streams, etc. that may flood certain areas of your property or disrupt the flow of drinking water. Another problem with beavers is that they carry diseases. Beavers carry diseases like rabies which they can pass by biting your pets, but this is not an issue usually. What is really dangerous about beavers is that they can give you Giardia which is no fun, and also carry parasites that can cause blindness, lymph gland problems and liver and lung failure.