River Otter

All posts tagged River Otter

By Jason Beale, Manager, Abbott’s Mill Nature Center

I set out to the Delaware Nature Society’s newest natural area, the Isaacs-Greene Preserve, with the intention of getting some photos of deer scrapes and rubs to write about their annual breeding season, the  rut.  However, as it often happens in nature, other discoveries present themselves as well.

Line of buck rubs. Look closely to see another rub in the upper left corner.

I did indeed find signs of the rut.  Rubs are found on small trees where bucks have used their antlers to remove strips of bark.  This serves two purposes.  It helps the buck shed the remaining velvet from his antlers and deposit scent from glands on the head to mark his territory.

Buck scrape. Notice overhanging vegetation above the scrape, a common association.

Scrapes are areas on the ground, usually a few feet in diameter, where a buck clears the ground and urinates to leave his scent.  Bucks often thrash the vegetation overhead and may use low hanging twigs to deposit scent from their pre-orbital glands in the corner of their eyes.  Does visit scrapes and urinate in them to let bucks know that they are ready to mate.  Both rubs and scrapes are often found along a well-used trail and are checked frequently by the attending buck.

This beaver made frequent tail slaps and "swim-bys" while I was in the area.

I next stopped by the Beaver Pond which was originally an irrigation pond created by damming Johnson’s Branch.  I was greeted by a loud tail slap, possibly a way to warn other beavers and animals of my approach.  The beaver then proceeded to swim toward me in a repeating crossing pattern punctuated by more tail slaps.  Beavers are often regarded as nocturnal or crepuscular (active around dawn and dusk), but where human contact is uncommon, they may be diurnal.

Otter scat containing fish scales and crayfish on


I followed the edge of the pond and came to a River Otter “haul-out” site. These are areas that otters frequent, usually along an open bank, to deposit scat, make scent mounds, and roll around.  This area has shown steady use for the few years that I’ve visited the site.

Northern River Otters at Reynolds Pond. Photo by Trevor Metz.


We’ll continue to maintain the Isaacs-Greene Preserve as a private conservation area, but we will begin offering forays by foot and canoe to the public starting in the spring.  However, we have already added the site into the Abbott’s Mill Nature Center Weekly Walk rotation.  We meet at the center parking lot every Thursday at 8am and hope you can join us.

By Derek Stoner, Conservation Project Coordinator

Paddling the placid waters of Dragon Run Marsh. July 31, 2010. Image by Derek Stoner.

Grab your favorite paddle and come along with us for a canoe trip to Dragon Run– no life preservers necessary!

After driving past the looming bulk of glowing metal towers at the Delaware City petroleum refinery, we hang a hard right on Clarks Corner Road and head south.  A mile later and we are at the put-in spot for our canoe adventure.  Many hands make light the work of unloading our watercraft, and soon we are underway.

A small flock of Little Blue Herons flies toward their roost on Pea Patch Island. July 31, 2010. Image by Derek Stoner.

Dragon Run is a vibrant freshwater marsh that has a narrow channel (run) carved through the dense aquatic vegetation.  The vast marsh is connected to the Delaware River one mile from our launching point,  and the water flows slowly in an eastward direction. As we paddle along, flocks of wading birds pass overhead: Little Blue Herons, Snowy Egrets, Glossy Ibis, and occassional Great Blue Herons and Great Egrets.  These elegant waterbirds are headed to their night-time roost on Pea Patch Island, in the middle of the river just below the Dragon Run outlet.

A pink Marsh Mallow glows in the late evening light at Dragon Run. July 31, 2010. Image by Derek Stoner.

We are visiting at the best time of year to view the spectacular blooms of aquatic wildflowers: white Lizardtail and Smartweed, purple Pickerelweed, pink Swamp Rose and Water Willow, and Marsh Mallows, a spectacular producer of plate-sized pink and white blooms.  A member of the Hibiscus family, the roots of the Marsh Mallow were utilized by English sweetmeat-makers to prepare a confectionary paste said to be of curative value in treating coughs and hoarseness. The ‘Marshmallows’  sold by confectioners today are the modern equivalent of this recipe (a mixture of flour, gum, and egg albumin), but no longer contain mallow root.

A Beaver lodge sits along Dragon Run, tucked amidst the Marsh Mallows. July 31, 2010. Image by Derek Stoner.

Besides the bounty of blooms, we are also hoping to spot another Dragon Run specialty: aquatic mammals!  This locale may be the best place to see the trifecta of American Beaver, River Otter and Muskrat, the only truly aquatic freshwater mammals in Delaware.  During a paddle of less than a mile, we encounter at least six active beaver lodges, and see the muddy platforms along the edge where the beavers and muskrats sit and chew aquatic vegetation.  A few slick “mud slides” are indications that the otters are around and taking advantage of the good fishing here, as bass, bluegill, and pickerel abound.  The canoes at the head of the group spot a few muskrats paddling along, and as we round a bend, an enormous beaver raises its tail and slaps the water with a resounding thwack!   Since they are not easy to see well in their underwater habitats, any encounter with these unique mammals is always thrilling.  

An evening paddle at Dragon Run is rewarded with a spectacular sunset. July 31, 2010. Image by Derek Stoner.

Towards dusk, we turn the canoes around and head back, into the setting sun.  A steady stream of Tree and Barn Swallows fly overhead, and we watch the twisting flight of Wood Ducks as they head to their night-time gathering place.  The western sky is lit up in orange and red hues, and the views are spectacular.   

For the whole trip, we’ve not seen or heard any other humans.  Quiet and solitude prevail, and the sense of being in a wild area is real.  Tucked away in a corner of bustling New Castle County, in the shadow of a major industrial plant, the delightful Dragon Run always manages to surprise and delight the visitors to her waters.

The Delaware Nature Society is leading another canoe trip meandering through the Dragon Run but under the light of August’s full moon!  Tuesday, August 24, leaving Ashland at 6:30; members can register on-line, non-members (can join on-line) or call in to sign up (239-2334.) No canoeing experience is necessary.    Listen to the sounds of nature while enjoying the unique experience of nighttime canoeing!

By Jason Beale, Abbott’s Mill Nature Center Manager

Many mammals “see” the world through their sense of smell, much more than humans.  Despite our use of perfumes and colognes in our mating rituals, we generally refrain from advertising or marking our territories through the use of smelly bodily substances (urine, feces, etc.)  However, for many mammals, especially those with large territories or low population densities, scent marking is extremely important.  In this case, we’ll look at some Northern River Otter scent marks.


Scent mounds are usually placed at or near prominent landmarks, natural or otherwise.  This dock along Abbott's Pond is a reliable spot to look for River Otter and American Beaver sign throughout the year

Scent mounds are usually placed at or near prominent landmarks, natural or otherwise. This dock along Abbott's Pond is a reliable spot to look for River Otter and American Beaver sign throughout the year

We encountered the above leaf and debris mounds during our weekly Thursday walk on January 7th.  You can see the scrapes where the vegetation was removed to form the loose mounds.  Close inspection shows piles of scat, featuring numerous fish scales.

Otter scats vary in shape, but are usually loose piles of fish scale

Otter scats vary in shape, but are usually loose piles of fish scale

Otters are members of the Mustelidae (Weasel family) which are closely related to the Mephitidae (Skunk family).  While the skunks are renowned for their highly developed anal scent glands, weasels also possess them and may use them when disturbed and to mark territories.  The following photo shows the yellowish-white secretions that Otters often mark sites with.

Otter secretions look very similar to the American Beaver's castoreum deposits which they use to mark their own territories.  Beaver mounds are generally constructed from mud and aquatic debris and can be quite large after multiple uses.

Otter secretions look similar to the American Beaver’s castoreum deposits.  Beaver scent mounds are generally constructed from mud and aquatic debris and can be quite large after multiple uses, up to 2′ high.  As both species use the same habitats, look for other clues to aid in identification.

Scent mound in front.  Note the scraped area beyond.
Scent mound in front. Note the scraped area in the upper left.

Have fun exploring outdoors and trying to make “scents” out of what’s going on.  Feel free to attend our weekly, free Thursday birding and nature walk at Abbott’s Mill Nature Center in Milford.  We meet at 8:00 a.m.