BACKYARD BIODIVERSITY: Cliff Chirping Frog

The Cliff Chirping Frog is an elusive creature. Nocturnal and about the size of a quarter, they are more easily heard than seen.

There are actually three species of Chirping Frog in the genus Eleutherodactylus in Central Texas. There is Eleutherodactylus marnockii. They are native and their range is central and western Texas as well as northern Mexico. There is also the Rio Grande Chirping Frog, Eleutherodactylus cystignathoides, a species that has been somewhat recently introduced through horticultural trading. They are smaller than the Cliff Chirping Frog, and the Rio Grande Chirping Frog’s chirps are higher in pitch. They are native to south Texas, but not Austin. Lastly there is the Greenhouse Frog (Eleutherodactylus planirostris)—native to Cuba and parts of the west Indies--which has been introduced to various parts of the southeastern U.S., including the Austin area.

For this post, we will be looking at the native species, the Cliff Chirping Frog, E. marnockii. This species is named after Gabriel Wilson Marnoch (1838-1920), a Texas frontier naturalist, rancher, and medical practitioner who collected natural history specimens and fossils. Marnoch’s story is an interesting one, to put it mildly. His father was Dr. George Frederick Marnoch, a contemporary of Charles Darwin who very likely attended class with him at the University of Edinburgh. He was also a naturalist, and his son Gabriel would follow in his father’s footsteps. In Texas, Gabriel Marnoch would send fossils to many different institutions around the country, and after he heard about one package’s contents arriving in pieces, he got into an altercation with the postmaster that did not end well. Marnoch murdered the postmaster, and through many difficulties within the justice system, managed to have the case eventually dismissed.

During fossil collecting, Marnoch discovered a few different amphibian and reptile species: the Texas Banded Gecko (Coleonyx brevis), the Short-Lined Skink (Plestiodon tetragrammus brevilineatus), the Barking Frog (Eleutherodactylus augusti), and of course, the subject of this blog, the Cliff Chirping Frog.

Breeding for this frog takes place in late winter through spring. The male will chirp loudly when a female is present. The call is hard to miss, but may often be confused with that of a nocturnal bird or insect rubbing its wings together. (Click here to listen to their chirps as well as those of the Rio Grande Chirping Frog).
 

Females lay eggs up to three times a year. Cliff Chirping Frogs do not undergo the typical metamorphosis of other amphibians where females lay eggs in a body of water that hatch into tadpoles. Rather, female Cliff Chirping Frogs will deposit their eggs in sheltered, humid areas, like leaf litter or soil beneath rocks. The young then develop and hatch as fully formed tiny froglets. When they first hatch, the froglets look like adults, except for a small tailbud that they will eventually absorb. Because Cliff Chirping Frogs don’t need access to a water source to lay eggs, they are able to occupy a greater variety of habitats away from permanent water as long as suitable moist hiding places are present (for example, rocks, log piles, planters, etc.)

Cliff Chirping Frogs do more than just hop, they can also run and crawl. Their external eardrum, or “tympanum,” is a large, circular membrane about the size of their eyes and located just behind the eye. They also have long back legs patterned with faint bars, although their pattern can be variable. The toes are unwebbed and have small toepads used to cling to rocky surfaces. Males often call from hidden retreats in rocky areas, which may serve to amplify the sound emitted by acting as a secondary resonator (the primary resonator being the frog’s vocal sac).

Thank you to Tom Devitt, Research Associate in the Department of Integrative Biology, for his assistance with this piece.

SOURCES

Ackermann, Ann Marie. “Death of a Texas Ranger: Interview with Author Cynthia Leal Massey.” Author Interviews: Historical True Crime in the United States, April 26, 2017. (accessed online: https://www.annmarieackermann.com/tag/gabriel-marnoch/)

Harrison, Chris. “The Central Texas Chirping Frogs: Eleutherodactylus cystignathoides vs Eleutherodactylus marnockii” Frog Blog, 2015. (accessed online: http://frogcalls.blogspot.com/2015/10/the-central-texas-chirping-frogs.html)

Herps of Texas: Cliff Chirping Frog. (accessed online: https://www.herpsoftexas.org/content/cliff-chirping-frog)

Price, Michael. “Wild About Texas: Cliff Chirping Frog” MyPlainview, March 10, 2015. (accessed online: https://www.myplainview.com/opinion/editorials/article/Wild-About-Texas-Cliff-Chirping-Frog-8390012.php)