Species Spotlight-The Native Beaver and the Invasive Phragmites

February 18, 2021

By Kaitlyn Skees, SUNY New Paltz Student/ Intern



The Native Beaver

We had a great opportunity to write about beavers (castor canadensis) this month, especially because they have been New York State’s official state animal since 1975. They helped New York City’s development due to their abundance in that area, which caught the attention of traders and trappers. Many issues such as hunting beavers, over-trapping, deforestation, and habitat loss (which were brought about by the increasing human populations in the area) led to the decline of the beaver population. They were close to extinction around the 1840s. However, efforts in the early 1900s were taken to try and increase the population, such as reintroducing the beaver population in the Adirondack Mountains. The efforts were very successful because the beavers in the areas increased within a few decades, and they continue to do well.

Beavers have a variety of impressive biologic features, such as sharp teeth, front feet that are adapted to land, back feet that are adapted to water, fur that is waterproof and provides insulation, facial features that help them while they’re underwater, and a dynamic tail that helps them both in water and on land. They build dams to create ponds and wetlands, as well as lodges either in the bank or in the middle of the pond to create their unique living environment.

Beaver Chew

Beaver chew on tree with ants on the fresh sap found in Mill Brook Preserve

Signs of beaver activity can be observed in New Paltz’s own Mill Brook Preserve (MBP), which is open to the public. The Wallkill Valley Land Trust holds conservation easements on the property to protect the land from development by humans forever. The beavers are able to continue their activities and hikers can witness the signs of beaver activity. The MBP includes land around the Mill Brook Stream where there are a variety of canals that are filled with branches and surrounded by trees. This makes a perfect place for beavers to settle because they have access to both the aquatic and land habitat. Beavers tend to be more active at night, when the MBP is closed. Therefore, it is best to just keep an eye out for traces of their activities such as trees that have been felled by the beavers and branches that have been chewed on for food. Within the MBP, the best place to observe signs of beaver activity is in the wetland area where the blue trail meets the green and yellow trails.

To help beavers thrive, some tips are: avoid interacting with dams, keep your distance, protect wildlife, preserve wetland habitats, and report beaver sightings. Reporting sightings of beavers is particularly helpful in areas like New York City because it helps with managing properties and planning for expansion.

For more information on how to report sightings, you can visit this link: https://www.dec.ny.gov/animals/30770.html.

Felled Beaver Tree

A felled tree from a beaver in New Hampshire


The Invasive Phragmite

The Phragmite (phragmites australis) is a subspecies of the common reed and is actually native to the Middle East and Europe. However, it has found its way into many areas of the United States. Phragmites came to this country from Europe in the late 1700s or early 1800s, most likely by accident as plant fragments in ship ballast tanks. They spread throughout the 20th century due to the construction of railroads and major roadways, habitat disturbance, shoreline development, pollution and eutrophication. This grass is a tall one, as they reach a height of about 3.3-11.5 feet (1-3.5 meters) and possibly up to 18 feet. In appearance, the phragmite has stems that are stout, unbranched, and hollow, long and flat leaves on one or two sides, and fluffy seed heads. Plumed flower spikes are produced in August or September, and will last through the winter.

Phragmites Phragmite Plumes

Phragmites are found wet and/or flooded areas, such as marshes, ponds, lakes, ditches, streams and rivers. This means that they are often growing in wetlands, which is where many animals, such as beavers, live. The Phragmite can get to these areas through spreading its rhizomes and stolons (which are different stem fragments) via water, machinery, humans, and animals.

Part of the reason the Phragmites are so disruptive to the natural wetland ecosystem is because they form dense, extensive, high-biomass colonies which will choke native species out. They also have underground mats that are formed by the rhizomes. This aspect of the species can be harmful because they can modify soil, vegetation, and take nutrients that native species would need.

Although dense patches of Phragmites can negatively impact our wetland habitat and the native species that rely on that habitat by altering the landscape, they can also be helpful in certain situations. The thick root masses help to trap sediment during high erosion events and will absorb pollutants from the water. For this reason, Phragmites have been used in tertiary wastewater treatment facilities. When the plant escapes into the native environment, it can prematurely dry up wetlands that would take thousands of years to fill, leaving the native species such as our beloved state animal, the beaver, without a proper habitat. A lack of wetlands also leads to increased flooding events and decreased groundwater recharge as the area is no longer able to act like a sponge during high water situations, making it unable to soak up the increased discharge and allow the water to slowly infiltrate the groundwater.

There are some ways to try and manage the species, such as repeating the process of mowing or burning for several years, the costly physical removal of the actual species, the targeted use of specific herbicides, or a combination of techniques. Researchers are working to come up with a biologic control to Phragmites which could help the invasive plant naturalize, meaning it would blend into the local ecosystems rather than take over and control those systems. With the plant being so widespread, a biocontrol may be the best way to tame this invasive species and protect our important natural resources.





“Beaver.” Smithsonian’s National Zoo & Conservation Biology Institute,



“Beavers.” WildlifeNYC, www1.nyc.gov/site/wildlifenyc/animals/beavers.page.


“Common Reed.” Invasive.orgwww.invasive.org/alien/pubs/midatlantic/phau.htm.


“Facts About Beavers In The Adirondacks.” Adirondack.net,



“Phragmites Australis.” Lower Hudson Prism, www.lhprism.org/species/phragmites-australis.


“Phragmites: Questions and Answers.” United States Fish and Wildlife Service,



Quinn, Erin. “Beavers Help Shape New Paltz’s Mill Brook Preserve.” Hudson Valley One, 8 Dec.

2020, hudsonvalleyone.com/2020/12/03/beavers-help-shape-new-paltzs-mill-brook-preserve/.


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