Ocracoke nature, flora & fauna

Ocracoke’s frogs love a summer evening rainstorm

Green treefrogs

By Peter Vankevich
Photos by Jeff Beane

After spring and summer rains on Ocracoke, the nighttime frog symphony begins.

This phenomenon was noted in the May 10, 1928, Statesville Record & Landmark, in which a reporter noted the frog crop on the island was the largest in years.

“One gets used to the singing in the low places at night. The frogs make away with mosquito larvas that might breed clouds of winged pests,” the story said.

Connie Leinbach recently made this recording of them after after a heavy evening rainstorm.

Lighthouse Road, a bit down from the Island Inn on the right, is one good area to hear them.

Frogs and toads are classified as amphibians and technically, a toad is a frog. To distinguish them, frogs usually have moist skin, while toads have dry bumpy skin.

It may be surprising to many that of the 30 species of frogs and toads in North Carolina only four, and a rare fifth, are most likely to be encountered on Ocracoke. The reason is that most of these amphibians are sensitive to salinity and do not do well in the brackish waters on barrier islands.

These are the Ocracoke salt tolerant species: squirrel treefrog, green treefrog, southern leopard frog, Fowler’s toad and the eastern narrow-mouthed toad.

Jeffrey Beane, the herpetology collections manager at the North Carolina Museum of Natural Sciences in Raleigh and a regular visitor to Ocracoke, offered the following thoughts about these amphibians on the island:

The frogs one most likely will see depends on the season, the time of day or night, the weather, where on the island you happen to be looking and what macro- or micro-habitat you are viewing.

If you only go out around the village and its buildings, you will most likely see squirrel or green tree frogs; they often hang out around porch lights at night to catch insects.

If you walk around the streets at night with a flashlight during the summer, looking at the ground, you will see Fowler’s toads all over the place, especially at Springer’s Point.

If you spend a lot of time out in the marshes and wetlands, you will probably see more southern leopard frogs than any of the others.

Another species, the eastern narrow-mouthed toad, is the least likely to be seen. Adults are small and secretive—usually living underground or under surface litter or sheltering objects. They were only recently confirmed to occur on the island and are rarely seen.

Here are some more details on each species.

Squirrel Treefrog (Hyla squirella)

From May into summer, these tiny frogs, only 1 to 1.5 inches in length, are more likely to be heard than seen. Throughout the day into night, they will make a series of roughly 15 loud nasal barking sounds over a period of about 10 seconds. When rain is approaching they also make a less noticeable raspy call that has been compared to the chatter of a squirrel from which it derives its name.

Don’t rely on color to identify these tiny frogs, they possess a chameleon-like quality and can vary from green to yellow and  brown, changing quickly in  order to  camouflage themselves. There may also be some spotting on the back. To help with identification, look for a faint bar between the eyes and a light stripe on the upper lip, shoulder and side of body.

Their geographical range is the southeastern United States, from southeastern Virginia to the Florida Keys, and west along the gulf plain to southeastern Texas. In North Carolina they are found primarily  in the Coastal Plain in a wide range of habitats, including urban areas.

Squirrel treefrogs are nocturnal and often seen at night on lighted windows where they feed on insects. They spend the daylight hours hiding under leaves, bark or logs.

Breeding occurs from April to August. They deposit eggs singly at the bottom of shallow, temporary pools and tadpoles require at least 7 weeks to complete metamorphosis.

During the winter, adult frogs will hibernate in groups together, under bark or in tree trunks or fallen logs.

Their diet consists primarily upon invertebrates such as spiders, beetles, termites, crickets and ants.

Predators in their tadpole stage include fish, dragonfly nymphs and water bugs. Adults enemies include birds, fish amphibians, small mammals and snakes.

Listen:

Recording of a squirrel treefrog courtesy of the Courtesy of OhioLINK Digital Resource Commons

Green Treefrog (Hyla cinerea)

This frog is slightly larger than the squirrel tree frog and is usually bright green with a white belly, but it can change color depending on temperature and lighting from olive to brown and they  often have orange or gold flecks on the back and a clearly defined ivory or yellow strip along the upper jaw and the sides.  Note the large toe pads and a white belly.

In North Carolina, they are found primarily in the Coastal Plain, where they can be extremely abundant along wetland margins and in swamps. Their wider distribution covers the central and southeastern United States, as far north  as southern New Jersey and as far west as central Texas.

Eggs are laid under water surface and are attached to roots of floating vegetation. Embryos hatch in a few days and tadpoles transform to adults in about two months.

As their name implies, they spend much of their lives in trees. Mostly nocturnal, during the day green treefrogs hide under vegetation in moist, shady areas. At night they feed primarily on flies, mosquitoes, moths and other small insects.

 Listen:

Recording of a green treefrog courtesy of OhioLINK Digital Resource Commons

Southern Leopard Frog (Rana [Lithobates] sphenocephala)

Southern leopard frog undergoing metamorphosis

This frog gets is named for its prominent spots, which are reminiscent of the sub-Saharan wild cat. The back color can vary from green to brown and has distinctive raised ridges down each side of the body. On each eardrum is a light spot and the belly is white or pale.  Their size can be between 2 and 3.5 inches in length.

This frog has an extensive range from southern New York throughout the  Southeast to Texas, Kansas, Missouri and extreme southern Ohio. In North Carolina, they are common  throughout most of the Coastal Plain and portions of the Piedmont.

They can breed throughout most of the year. Eggs hatch in a week or two and the tadpoles take about 12 weeks to metamorphose to the adult stage.

They can spend time on land, foraging on primarily on insects as well as arthropods and worms. Their predators include herons, ibis and snakes.

The call is usually a series of guttural croaks followed by a clucking or chuckling trill, which some people compare to the sound produced by rubbing an inflated balloon.

Elsewhere, the southern leopard frog is sometimes confused with the closely related pickerel frog (Lithobates palustris), which is distinguished by its more squarish spots and bright orange or yellow coloration on the concealed surfaces of its thighs. The two species can also be distinguished by their calls.

Listen to a southern leopard frog:

Courtesy of OhioLINK Digital Resource Commons

.Fowler’s Toad (Anaxyrus fowleri, formerly Bufo fowleri)

Active both day and night, the Fowler’s Toad can venture far from water, spending time in yards in the village and are almost guaranteed to be seen during a day walk at Springer’s Point and along the trail of Hammock Hills across from the NPS campground.

They have dark warty spots and the overall color can vary from brown,  grey, olive green and even a rufous tinge. Adults have a pale stripe on its back and all have  a whitish bellow with a dark spot.

Size can vary from two to nearly four inches in length.

They are active much of the year, but in cold weather will burrow into the ground and hibernate, emerging in April.

Present throughout much of North Carolina, they are present in suitable habitats in most areas of eastern United States from southern New Hampshire south to northern Florida and west to Michigan, eastern Oklahoma, and eastern Texas. There is also a small population in Ontario are listed as Endangered under the Canadian federal Species at Risk Act. Efforts are underway to protect their habitat. 

Breeding occurs in the spring or early summer calling in mid-April when the males begin calling from shallow waters; breeding occurs in wetland areas. Females lay eggs in strings with clutches of up to 20,000 eggs. Eggs are often laid after heavy rains. Eggs and larvae develop in shallow water of marshes, rain pools, ponds, lakes, reservoirs, flooded areas and other bodies of water lacking a strong current. Tadpoles go through metamorphosis within two months of hatching.

They feed on insects and other small terrestrial invertebrates. Would be predators may encounter skin secretions that are toxic or distasteful.

Listen:

Courtesy of OhioLINK Digital Resource Commons

Eastern Narrowmouth Toad (Gastrophryne carolinensis)

Though not considered to a true toad, this is the least likely of our five amphibians to be encountered on Ocracoke. The eastern narrowmouth toad is a small, plump toad with a small, triangular-shaped head and a tiny mouth with short limbs They are usually dark colored, ranging from gray to reddish brown, often with a broad, irregular light band running down each side. In North Carolina they are found in the Coastal Plain and Piedmont. Their North American distribution range is from southern Maryland to the Florida Keys, west to Missouri and Texas.

Nocturnal feeders, they spend the day buried or hidden under leaves, logs and debris in moist places. The skin secretions of narrowmouth toads can be irritating to human eyes and mucous membranes so they should be handled with care. 

Narrowmouth toads breed between April and October, usually during or after heavy rains on warm nights. Black-and-white eggs are laid on the surface of the water, and transformation from tadpoles to adults can take between three to 10 weeks.

Listen:

Courtesy of OhioLINK Digital Resource Commons

 

Jeff Beane. Photo by Todd Pusser

Jeff Beane is the Collections Manager for Herpetology at the North Carolina State Mu­seum of Natural Sciences.

In 2015, he was awarded the prestigious Thomas L. Quay Wildlife Diversity Award and has received recognition for his commitment to wildlife diversity conservation, including the Governor’s Conservation Achievement Award as the 2012 Wildlife Conservationist of the Year, presented by the N.C. Wildlife Federation and the Extra Effort Award, presented by the N.C. Partners in Amphibian and Reptile Conservation in 2014.

 

 

Peter Vankevich is co-publisher of the Ocracoke Observer and hosts “What’s Happening on Ocracoke” on WOVV, Ocracoke’s community radio station. His writings include nature stories on Ocracoke and he is the compiler of the Ocracoke and Portsmouth Island Christmas Bird Counts.