Category: River Critters

River Otter (Lontra canadensis)

by A. Karuna Lohmann

The Narrow River Preservation Association chooses a different organism as its mascot annually to depict on the logo of the Narrow River Turnaround Swim T-Shirt. This year it is a North American River Otter (scientific name Lontra canadensis). Although the River Otter is abundant in Rhode Island, it is rarely seen because it is shy and lives mainly on land. A good indication of its presence, however, are the piles of shells and fish scales it leaves scattered on rocks and banks (Reid 471).

If you have seen a photo of an otter before, an image may come to mind of a cute creature swimming on its back, head above water. This image would be of a Sea Otter (scientific name Enhydra lutris), not a River Otter because the habit of swimming on its back is a key characteristic that distinguishes the Sea Otter from the River Otter (“River Otters | Seattle Aquarium”). Although both species are members of the weasel family Mustelidae, they can be distinguished in numerous ways. Most importantly, unlike the Sea Otter, the River Otter predominantly lives on land. In winter it uses water bodies including iced-over lakes to find food (“River Otters | Seattle Aquarium”) and breathes using air pockets under the ice (“River Otter Wildlife Note”). It also has a playful habit of sliding and galloping across ice. The two otter species also differ in size and coloration. The Sea Otter lives only in the Pacific Ocean (“Scientific Classification”).

Here’s a video of an otter in South Kingstown, RI. Many thanks to Elise Torello for the use of her video.

The River Otter is large, with a body spanning 26-31 inches. As a semi-aquatic animal, it has a thick tapered tail, broad webbed feet, and a streamlined form that makes it well-adapted to both land and water. In contrast, the Sea Otter is three times as large and has a narrower tail. The River Otter’s sleek coat is rich brown with a silvery underbelly and its pale orange eyes have a bright eyeshine (Reid 471). The sensitive whiskers on its muzzle are used to hunt various fish, which are an important part of its diet. The River Otter also preys on shellfish, amphibians, reptiles, insects, birds, and other mammals.

The River Otter is native to North America. It is found in the Eastern United States, Alaska, and large swaths of Canada. In these regions, the River Otter’s primary habitat is land near marine and freshwater bodies of water, such as Narrow River and Narragansett Bay, where it lives in above or below-water dens or abandoned shelters of other animals (“River Otters | Seattle Aquarium”). Breeding occurs in the spring. Females normally have a litter of 2-4 pups that they raise alone (Brown 3).

Although the River Otter population has declined in America in the past due to the pollution of its habitat, protection of the species and water quality monitoring have slowly aided their comeback (Brown 3). Likewise, in Rhode Island, the passing of legislation, the creation of habitats, and the improvement of water quality have helped the River Otter population rise and stabilize (Brown).

Works Cited

Brown, Charles. “Species Spotlight: River Otter.” Wild Rhode Island, 2009, pp. 3–4. Division of Fish and Wildlife, RI Department of Environmental Management, dem.ri.gov/sites/g/files/xkgbur861/files/programs/bnatres/fishwild/pdf/wriwin09.pdf.

Reid, Fiona. A Field Guide to Mammals of North America North of Mexico. Boston, Houghton Mifflin Co, 2006.

“River Otter Wildlife Note.” Pennsylvania Game Commission, 2023 www.pgc.pa.gov/Education/WildlifeNotesIndex/Pages/RiverOtter.aspx.

“River Otters | Seattle Aquarium.” 2023 www.seattleaquarium.org, www.seattleaquarium.org/animals/river-otters.

‌ “Scientific Classification” 2023 https://seaworld.org/animals/all-about/otters/classification/#

Glossy Ibis (Plegadis falcinellus)

Featured on NRPA’s 2016 Road Race T-Shirt

By Craig Wood

Each year NRPA features a local bird species for the Narrow River Road Race T-Shirt, and this year it’s the Glossy Ibis. While the Glossy Ibis does not nest along the Narrow River, it is a relatively common sight in the summer foraging in small flocks within salt marshes for insects, mollusks and crustaceans. Its diet typically does not include fish.

The Glossy Ibis is a medium-sized wading bird, standing up to 26 inches in height. It is easily distinguished from other local wading birds (herons and egrets) by their dark appearance and long, down-curved bill. Unlike herons and egrets which fly with their necks retracted, the ibis flies with its neck stretched out. Touch sensors on the down-curved bill allow the ibis to rapidly snap it closed as it probes the substrate when it encounters prey, while ridges along the bill help to securely grasp it in place. The scientific name, Plegadis falcinellus, is derived from the Latin word Falx, meaning sickle, referring to the bird’s distinctive bill.

While they appear dark at a distance, adult birds are chestnut colored with an iridescent purple gloss on the head, neck, and underside. During the breeding season, bare facial skin becomes a cobalt blue trimmed with a thin band of white. Immature birds are similar to adult, but with a dark banded bill, duller body and a neck covered with light streaks.

The most widespread of all ibis species, the Glossy Ibis is found in North, South and Central America, as well as Europe, Africa, Asia, and Australia. Glossy Ibis are originally from Africa and immigrated to the South American continent in the nineteenth century. In North America, the Glossy Ibis nests in a narrow band along the Atlantic and Gulf Coasts. The species is migratory and nomadic, those found in Rhode Island may wander widely before migrating southwards to wintering grounds.

Glossy Ibis nest in small mixed colonies with other wading birds, such as Great Egrets and Black-Crowned Night Herons, on predator-free islands in Narragansett Bay. Both the male and female help to construct the nest, built of sticks and twigs in trees or shrubs up to 10 feet from the ground. Both parents incubate the eggs (typically 3-4), the female usually attends the nest at night and the male during the day.

First spotted in Rhode Island in the 1930s, the first recorded nesting in this state was in 1971. This species can display great volatility in the number of nesting pairs, with a Rhode Island population peaking at 500 nesting pairs in 1991, and then declined slowly to 135 pairs in 2013. According to RIDEM biologist Chris Raithel, there were about 200 nesting pairs of Glossy Ibis in Rhode Island last summer. Nationwide, the species is considered a low conservation concern and continues to expand its range. However, due to their small population size in Rhode Island, this species is a local conservation concern.

Many thanks to Johann Schumacher for use of the beautiful photo of the Ibis in flight.

Learn more on these websites:

https://www.allaboutbirds.org/guide/Glossy_Ibis/id

https://www.audubon.org/field-guide/bird/glossy-ibis

The Willet (Tringa semipalmata)

By Craig Wood

The featured bird for the 2017 Narrow River Road Race T-shirt is the Willet (Tringa semipalmata). The Willet is one of our most conspicuous breeding species in the Narrow River estuary. They are large, stocky shorebirds (pigeon-sized body on long legs) with distinctive black-and-white wing markings. Willets have a thick, straight bill considerably longer than the head. Willet plumage is mottled brown during breeding and plain gray in winter. When startled, they take flight with a piercing “pill-will-willet” call that gives them their name. Willets are often seen alone. They walk deliberately, pausing to probe for crabs, worms and other prey in sand and mudflats, or to pick at insects and mollusks.

There are two nesting populations (subspecies) of Willet in North America; the Eastern Willet nests in salt marshes, barrier beaches, and mangroves along the Atlantic and Gulf Coasts from Newfoundland to northeastern Mexico. The Western Willet breeds in interior prairies from Alberta to Colorado. Eastern Willets winter in coastal eastern South America, whereas Western Willets winter on both coasts of North America south to Peru.

Interestingly, the Willet is a southern species that has extended its breeding range north in recent decades. Willets were first documented nesting in Rhode Island during 1987 and are now a locally common breeding species throughout the state. With an expanded breeding range, Willets are now also a common sight in Rhode Island during mitigation periods, especially during fall migration which occurs locally throughout July. Western Willets are sometimes observed in Rhode Island with flocks of Eastern Willets during fall migration.

Willets, along with the salt marsh sparrow (Ammodramus caudacutus), nest in the higher portions of salt marsh bordering Narrow River. This “high marsh” habitat has been disappearing in salt marshes throughout the region. This phenomenon is thought to be the result of accelerated sea level rise. Restoring high marsh is a major objective of the on-going dredging and marsh building project which is placing dredged material on the surface of the marsh to raise the elevation combating drowning and loss of habitat.

Cool Facts

• Although both parents incubate the eggs, only the male Willet spends the night on the nest.
• Willets and other shorebirds were once a popular food. By the early 1900s, Willets had almost vanished north of Virginia. The Migratory Bird Treaty Act of 1918 banned market hunting and marked the start of the Willet’s comeback to present numbers.
• Like Killdeer, Willets will pretend to be disabled by a broken wing in order to draw attention to themselves and lure predators away from their eggs or chicks.
• Because they find prey using the sensitive tips of their bills, and not just eyesight, Willets can feed both during the day and at night.
• Willet pairs often remain together for several years and return to the same nest sites.

Sources:

Rhode Island Wildlife Action Plan Species Profiles, Species of Greatest Conservation Need, accessed at http://www.dem.ri.gov/programs/bnatres/fishwild/swap/SGCNBirds.pdf.

All About Birds, The Cornel Lab of Ornithology, accessed at https://www.allaboutbirds.org/guide/Willet

Willet in Flight over Winnapaug Pond by David Uliss

Please don’t feed the waterfowl!!

Not only is it harmful to the bird, it’s banned in Rhode Island. Read more about it here.

North Atlantic Blue Crab (Callinectes sapidus)

Color: Olive green carapace, with brilliant blue claws. Females have red-tipped claws.

Size: Up to nine inches long from point to point, and four inches from head to tail.

Habitat: Shallow and brackish waters, eelgrass beds, muddy bottoms.

Seasonal appearance: Early spring to late fall. Description Blue crabs belong to the family of swimming crabs that also includes the lady crab.

This crab has a characteristic sharp spine projecting outward from each side of its carapace. The rear pair of legs acts as paddles, making these crabs excellent and rapid swimmers. The blue crab has two, stalked, compound eyes, which are controlled separately and can lay back into sockets in the shell.

Life History and Behavior: Blue crabs, like all crustaceans, grow by molting, or shedding their shell. Blue crabs molt every few weeks when they are young, but only once a year when they are older. Molting begins when a thin line appears down their backs. For adult crabs, molting occurs in the summer months, leaving them soft and defenseless for several days. At this point, they are known as “peelers.”

Blue crabs are commonly found in Rhode Island waters, although the largest population is found in the Chesapeake Bay.

The name Callinectes sapidus comes from the Latin “beautiful, savory swimmer.” As a predator, they burrow in mud with only eyes and antennae showing. Even the slightest shadow can trigger a reaction from the blue crab.

Blue crabs aggressively take on any opponent by raising claws toward their enemies while scuttling sideways to escape. They eat bivalves, crustaceans, fish, snails, live plants, dead animal matter, and even other blue crabs. Through their voracious feeding habits, they help regulate the populations of benthic organisms on which they feed.

Blue crabs are preyed upon by skates, striped bass, coastal birds, oyster toadfish, bluefish, and even sea stars during the crabs’ dormant winter months. While soft-shelled, crabs are easy prey for wading birds, other crabs, and mammals.

Special Notes

Prized seafood in their soft-shell state, blue crabs can be cooked and eaten whole, shell and all. They are harvested using dredges, crab pots, hand lines, and dip nets. Once plentiful in Rhode Island, the number of blue crabs has significantly reduced because of the pollution and the destruction of their nursery, molting, and foraging habitats.

Blue crabs need highly oxygenated water to survive. Nutrient pollution, including phosphorous and nitrogen from sewage plants, farm fields, and lawns, causes algal blooms. When the free-floating algae die and decompose, large quantities of dissolved oxygen are consumed. Under these low oxygen conditions, blue crabs will emerge from the water in large numbers to escape the deadly, deoxygenated water.

Adapted from The Uncommon Guide to Common Life on Narragansett Bay. Save The Bay, 1998.

NRPA featured the Blue Crab in the logo for our 11th Annual Turnaround Swim in 2016.

Learn more about Blue Crabs from the National Oceanic and Atmospheric Administration’s Fisheries Department.