Naturally Curious about Beavers

Naturally Curious: Ecosystem Engineers

Wetlands are crucial — roughly 85 percent of all native North American wildlife relies on them — and throughout most of North America wetlands are highly correlated with beavers.

 When the beaver population plummeted due to fur trade in the 18th and 19th centuries, the number of beaver wetlands did as well. Today, beavers number around 6 million to 12 million, and the number of ponds is estimated to be between 1.5 million and 7.7 million. This had an enormous impact on the flora and fauna in and around these wetlands, changing the distribution and abundance of many plants and animals.

If you want to know why the state of New Hampshire is having such positive public support for beavers, it’s entirely because of articles like this. Mary Holland is a talented author and breathtaking photographer who donated generously to our silent auction in the past. She likes to write about beavers sometimes, but this is the most glowing advocacy I’ve seen from her yet. I’m hoping that we influenced her work in some small way. There is so much I want to share I can barely pick and chose. Make sure you click on her article  just so she gets credit for this remarkable work. Here’s a treasure hunt for motivation: there is one thing she got wrong. But only one. See if you can find it.

Vegetation

 Studies have shown that by increasing the diversity of habitats, beavers increase the number of species of herbaceous plants. By expanding wetland habitat, beavers provide an ecological opportunity for new plant species. The riparian vegetation — plants on a pond’s banks — not only increases in number of species, but the vegetation becomes denser as a result of beaver activity.

Insects

A beaver dam slows the current of a stream and increases deposition of nutrient-rich sediment and organic material in the water. This plays a key role in the development of insect life. The variety and density of species increases, providing more food for fish, birds and mammals.  Although one would think that the presence of a beaver pond might increase

Fish

 As one would expect, there is a shift in fish species, just as there is in insect species, as the rapidly flow ing stream is converted to the stillness and increased warmth of a pond. Studies have shown that fish species richness increases with the size of a pond, but even very small beaver ponds can have higher than expected richness compared to ponds of a similar size not impounded by beaver dams.

 Contrary to popular belief, beaver ponds have been shown to have a beneficial effect on trout and salmon populations. Loss of beaver ponds has been correlated with a significant reduction in salmon production. Beaver dams are typically not barriers to fish — they find ways of passing through them, except when stream levels are very low.

Amphibians and Reptiles

 Beaver ponds create an ideal habitat for amphibians. Reptiles also fare well in beaver ponds, especially older beaver ponds. There is greater species diversity of snakes and turtles in older ponds than younger ones, but even younger beaver ponds usually have more species than undammed streams.

 Mammals

 A wide variety and number of mammals uses the lush vegetation around beaver ponds as food and cover. An increased production of woody plants (vigorous shoot growth at beaver-cut stumps) and aquatic vegetation attracts browsing moose and deer. Water-loving muskrats, otters, raccoons and mink frequent beaver ponds for food and shelter.

 Birds

 The creation of an aquatic habitat necessarily will attract different species of birds than a forest habitat. Significantly more bird species have been found at active beaver ponds than abandoned beaver ponds and control sites with no history of beaver occupation. Waterfowl use beaver ponds for nesting and rearing young, and as stopover sites during migration.

Mary’s Closing argument:

Humans may disagree about the advantages and disadvantages of having beavers as neighbors, but there is no disputing the fact that beavers play an important role in preserving biological diversity.

And THAT’s what the New York Times SHOULD have said. (By the way I just heard that the NYT beaver article is tracking as the 6th most emailed!)

Thank you so much Mary for singing beaver praises with such passion and timbre! We are grateful for your eloquence, talent and veracity. I’m sorry the grey lady pushed your work out of the spotlight for a whole day, but I am so thrilled to promote your work now!

And if you need a little more illustration to the argument that beavers create habitat, here’s some recent footage from Rusty Cohn in Napa showing an unexpected visitor to the beaver dam. He wondered, fox or coyote? So I sent it to the expert. This morning Camila wrote back: COYOTE!

We have been so inspired by his work we tried our own trail cam last night for the first time, but all we got was the “Lesser-spotted-Moses” hard at working cleaning up a tree so the city wouldn’t be annoyed at the beavers. Recognize this species?