Do Beavers Eat Fish? (Here’s What They Do)

American beaver eating bark
Seney Natural History Association / Flickr / CC BY SA 2.0

Beavers have a special relationship with the water. Not only do they live in wetlands, but they actually build dams and water lodges and swim for most of the day. Their semi-aquatic nature makes many people believe that beavers eat fish. But do they?

Do Beavers Eat Fish?

No, beavers do not eat fish. They are strict vegetarians and don’t eat any type of meat or animal-derived foods, such as birds’ eggs or honey. A beaver’s diet consists of soft vegetation in summer and tree bark in winter. This semiaquatic mammal lives in lodges built on the water to stay out of the reach of predators. 

Beavers are the largest rodents in North America and Eurasia. When thinking of them, most people envision either a laid-back mammal floating or swimming in ponds or a terrible pest that uses its teeth to cut down trees.

It is the relationship with the water and the beaver’s resemblance to the otter that makes some people believe that beavers eat fish.

However, beavers do not eat fish or other types of meat. They are strict vegetarians, which means they only eat plants. In a modern understanding, we might say that beavers are vegan (although they could ingest insects or larvae resting on the leaves that they eat; thus, they are considered vegetarians).

Otters are a carnivorous species that often lives in the beaver habitat, taking advantage of the abundance of fish in the dams. They are also semiaquatic and can be mistaken for beavers from a distance. This is why some people believe that beavers eat fish.

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How Do Beaver Dams Affect Fish?

Although beavers are vegetarians and never eat fish, the rodents interact with native fish populations through their dams. 

For a long time, it has been believed that these dams have a negative impact on native fish species. However, the contrary is true.

Beaver dams built on rivers create artificial ponds that increase the diversity of the river habitat. For numerous fish species, including bass, trout, and salmon, beaver dams are nothing but safe havens that provide both food and shelter and that turn out to be ideal nurseries for juvenile fish.

Most native fish species have coexisted with beavers for hundreds if not thousands of years. 

Thus, the sediment accumulation resulting from the damming activity has little to no impact on the fish egg development. 

In fact, native fish generally lay their eggs on the downstream sides of the beaver dams. This location is strategic, as the sediment is less likely to accumulate on this side, and the water is richer in oxygen, allowing the fish to develop inside the eggs and hatch.

The upstream side of the dam blocks the rapid flow of the river and creates a tranquil habitat for adults and juveniles alike. Native fish gather in these ponds thanks to the abundance of nutrients. This is why otters often establish their dens near beaver dams or occupy abandoned beaver lodges.

Do Beaver Dams Stop Fish Migration?

As explained above, native fish take advantage of the habitats created by beaver dams and know how to coexist with these rodents. 

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Most fish living in the same habitat as beavers are trout and salmon. Both species are known to leap over obstacles. They have also been seen swimming over beaver dams in both directions. Thus, scientists concluded that beaver dams are not acting as movement barriers for native fish, nor do they impede dispersion. 

Things are different in the case of non-native species introduced to re-colonize rivers. Fish species that have not coexisted with beavers might not have the strategies to overcome the physical barrier. Dams may also create impediments to downstream fish migration during droughts. 

Overall, though, beaver-induced habitat modifications have more positive than negative effects. Specialists also observed regional differences in the beaver and fish interactions, with a mostly positive impact in North America and slight negative effects in some European areas.

What Do Beavers Eat?

As you have noticed, beavers interact with native fish species, but they don’t eat fish. So, what do beavers eat?

Here is a list of foods beavers consume: 

  • Tree bark 
  • Leaves 
  • Twigs
  • Grass
  • Fern
  • Aquatic plants
  • Shrubs 
  • Some crops

Like most herbivores, beavers prefer soft vegetation. Their summer diet consists of grass, aquatic plants, leaves, ferns, and green twigs. In fall, beavers start to prepare for winter and eat more to build up fat deposits. Their autumn diet often includes berries, acorns, nuts, and seeds, alongside twigs and leaves. In winter, they mostly eat tree bark but can be seen foraging when the weather is warm enough. If they get access to a garden or orchard, beavers will also eat carrots, potatoes, or apples.

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Read More About Beavers:

  1. What Do Beavers Eat?
  2. Do Beavers Eat Meat?
  3. Do Beavers Eat Wood?
  4. What Eats Beavers?
  5. Do Beavers Hibernate or Migrate In Winter?

James Ball

James has had a lifelong passion for animals and nature, tracing back to his childhood where he first began fostering intimate knowledge and connection with pet frogs and snakes. He has since honed this interest into a career as a trained Wildlife Biologist, specializing in Biogeography, sustainability and conservation. In addition to his professional pursuits, James maintains an active lifestyle, regularly indulging in outdoor activities such as hiking, and musical pursuits like playing piano and swimming.

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