fauna – Ogeechee Riverkeeper

Blog Post crabs, crustaceans, fauna, invertebrates

Fauna: Callinectes sapidus

by Ogeechee Riverkeeper May 1, 2024

Fauna: Callinectes sapidus
Blue crab (and others)

The Ogeechee River basin is teeming with a diverse array of crab species, each with its own unique characteristics and role within our aquatic ecosystems. From the feisty blue crab to the elusive stone crab, these fascinating creatures play a vital role in maintaining the delicate balance of life in our rivers and estuaries.

Perhaps the most well-known of all crab species in our region, the blue crab is a true symbol of the coastal South. With its distinctive blue claws and sweet, succulent meat, the blue crab (Callinectes sapidus) is a favorite catch among recreational and commercial fishermen alike. But beyond its culinary appeal, the blue crab also serves as an important predator and scavenger, helping to control populations of small fish, mollusks, and other invertebrates in our estuarine habitats. Eggs of blue crabs hatch in salty waterways like inlets, coastal tributaries, and mouths of rivers, and are carried to the ocean by ebb tides. Eventually, young crabs settle to live in brackish water. These estuaries are also needed for crabs to complete their molting and growing cycles.

Red-jointed Fiddler Crab Photo by Emilio Concari

If you’ve ever explored the muddy shores in our basin, chances are you’ve encountered the industrious fiddler crab (Minuca minax). Commonly known as the red‐jointed fiddler crab or brackish-water fiddler crab, they are known for their oversized claws and distinctive “fiddling” behavior, these small but mighty crustaceans play a vital role in shaping the structure and stability of our coastal marshes. By burrowing into the soft mud and feeding on organic matter, fiddler crabs aerate the soil, increase nutrient cycling, and provide habitat for a variety of other marsh-dwelling organisms.

Juvenile Stone Crab. Photo by Andrea Westmoreland

Less conspicuous but no less important are the stone crabs (Menippe mercenaria) that inhabit the rocky substrates of our river bottoms and oyster reefs. In addition to the typical molting cycle, these crabs can also lose a limb and easily grow it back. With their powerful claws and voracious appetites, stone crabs play a crucial role in controlling populations of bivalves and other shellfish, helping to maintain the health and productivity of our estuarine ecosystems.

Atlantic Ghost Crab. Photo by Kris Howard

The Atlantic ghost crab (Ocypode quadrata) is an omnivore that needs sandy beaches for its habitat. A great deal of its habitat has been affected by beachgoers or other human interaction. They are also typically nocturnal, so it is rare to spot them on a day by the shore. In 2023, a study showed that these crabs had self-awareness and could recognize themselves in a mirror.

Blog Post fauna, Lontra canadensis, river otter

Fauna: Lontra canadensis

by Ogeechee Riverkeeper February 23, 2023

Lontra canadensis
North American river otter

River otters can thrive in a variety of environments – hot, cold, low lying, mountainous – including freshwater and coastal marine habitats, like rivers, lakes, marshes, swamps, and estuaries. They need a healthy environment with plentiful food sources, and they will quickly move to other environments if there is pollution in their area. Water quality issues and loss of aquatic or wetland habitats pose long-term threats to the overall health of river otter populations.

They are semi-aquatic animals, meaning they live in and near water, but are land mammals. Their soft, dense fur keeps them warm in the variations of their environment. They have tiny ears and nostrils which they will close up when going underwater to hunt and fish. Their webbed feet help them swim while their claws allow them to dig up food or pry open prey. In the Ogeechee River basin, their main prey is crayfish.

River otters make their dens in the burrows of other mammals or in natural hollows, such as under a fallen tree, or tucked into river banks. They build underwater entrances for their dens, which protect a nest that otters will line with leaves, grass, moss, bark, and hair. Otter families tend to respect the boundaries of other otter territories.

Mating pairs will give birth to one to six pups per year, usually in the spring. They need their mother until they are about three months old. River otters can live more than 20 years in captivity, but typically live about nine years in the wild. Males can reach 25 pounds and females average about 18 pounds when they are adults. Their tail is about a third of their length.

River otter. © Oregon Zoo / Photo by Shervin Hess

They can stay underwater for about eight minutes and typically hunt at night. They are known for being “playful” as they can often be seen diving and swimming in waterways. They are also noted for using tools, such as rocks, to open the shells of the bivalves.

Blog Post, Creature Feature creature feature, fauna, Perimyotis subflavus, tricolored bat

Fauna: Perimyotis subflavus

by Ogeechee Riverkeeper October 4, 2021

Studio portrait of a tricolored bat, National Geographic Photo Ark

Tricolored bat
Perimyotis subflavus

Tricolored bats are very small, weighing about the same as a U.S. quarter, though its wingspan can reach up to 10 inches across. Their fur is a mix of black, brown, and light brown, giving them their name. The species used to be called Eastern pipistrelle, but a 2019 DNA test showed they in fact are not related to the Pipistrellus genus. The new genus, Perimyotis, indicates its similarities with the Myotis or mouse-eared bats.

The first known specimen was collected in Georgia by John Eatton Le Conte, a naturalist and a captain in the United States Army Corps of Topographical Engineers. Among other locations, he was stationed in the Savannah harbor and at Ossabaw Sound. Le Conte’s tricolored bat specimen was studied and categorized by zoologist Frédéric Cuvier in 1832.

Tri-colored bat with visible WNS symptom, USFW, Darwin Brock

Males are solitary, while females can sometimes be found living in small colonies. They may take up residence in a cave but they are also found in trees, overhanging water. Scientists have also recently discovered colonies living in tree lichen (like Spanish moss), presumably because the lichen has natural anti-fungal, anti-bacterial, and anti-insect properties. This is especially important as the tricolored bat is susceptible to the deadly white-nose syndrome, which has killed about 70% of the population since 2006. Though numbers have stabilized, this bat remains on the Endangered Species List as “vulnerable and threatened.”

Like most bats, this species hunts in early evening and at night, using echolocation to find its prey. It eats mainly insects like mosquitoes, moths, cicadas, and ants. It loves to hunt in areas near water, especially. It’s a very efficient hunter and is able to consume a quarter of its own weight within a half an hour.

Blog Post, Creature Feature acipenser brevirostrum, creature feature, fauna, fish, shortnose sturgeon, sturgeon

Fauna: Acipenser brevirostrum

by Ogeechee Riverkeeper October 4, 2021

Shortnose sturgeon
Acipenser brevirostrum

The shortnose sturgeon is a hefty freshwater fish that can be nearly five feet long, weigh upwards of 60 pounds, and generally live about 30 years — some females have been known to live 70 years! Though they can be found feeding in saltwater environments, they live, and spawn, entirely in coastal, freshwater rivers, including the Ogeechee.. Because of this, their survival depends on two types of healthy ecosystems. Shortnose sturgeon are currently listed on the Endangered Species List.

Native Americans fishing, John White, 1530. Public domain.

Sometimes called a ‘living fossil,’ the shortnose sturgeon has been thriving in coastal areas for millions of years. There is evidence that the species has been fished by humans for at least 4,000 years. However, overfishing contributed to a swift decline in the late 1800s. According to NOAA, In 1890, more than 7 million pounds of sturgeon were caught in that year alone. In 1920, only 23,000 pounds of sturgeon were caught.

Their trademark ridged back is formed by bony plates called ‘scutes,’ giving them the appearance of armor. They lack teeth but have bony plates in their esophagus which serve to crush their food. They use their barbels — sort of like fish antennae — to find insects, crustaceans, and bivalves on the ocean floor or river bottom.

Due to their low numbers, protecting their habitat and spawning ability is crucial to the species population. Sturgeon require free flowing, unobstructed rivers and streams in order to swim upstream and spawn. They also need healthy intertidal zones to feed and rest.

Blog Post, Creature Feature bird, creature feature, fauna, Pandion haliaetus, western osprey

Fauna: Pandion haliaetus

by Ogeechee Riverkeeper September 27, 2021

Western osprey
Pandion haliaetus

This large bird of prey can often be spotted in the Ogeechee watershed as they feed almost exclusively on live fish. They are adept hunters, diving in shallow waters and pulling up fish in their opposable talons. As a species they have adapted fairly well to living near human settlements. They often built sturdy nests on tall structures like telephone poles and channel markers, as well as trees overlooking waterways.

The nests are put together from sticks and other natural materials but can grow to be more than 10 feet wide over many years. Aside from breeding and nesting, ospreys are usually solitary birds. They hatch 1-4 fledglings each year and their numbers have stabilized since the ban on DDT which harmed their eggs.

The birds seem to live about 15-20 years, and according to the Cornell Lab of Ornithology, they have been known to log more than 150,000 migratory miles in their lifetime. One can spot the osprey with its mostly white coloring, especially on the underneath side of their nearly 6-foot wingspan. They sport the well-known hooked beak look of a bird of prey.

You can watch local osprey nests on Skidaway Island. The live cameras are operated by Skidaway Audubon and Cornell Lab of Ornithology. Watch baby ospreys grow up, leave the nest, and adults come home to roost, or choose clips of past highlights.