Rio Grande Chirping Frog (Eleutherodactylus cystignathoides)
Description and Morphological Characteristics
Rio Grande Chirping Frogs are small bodied frogs that range from 5/8-1 inch in length, and are typically grayish-brown with olive, and sometimes yellow, undertones. They have an elongated, flattened body, with a pointed snout and long slender toes with prominent tubercles. A dark line/shadow that extends from eye to nostril is one of the more distinguishing characteristics usually present in individuals of this species. Most individuals feature dark spots randomly scattered across their back. The skin is translucent on the ventral side of the body, through which blood vessels are visible and appear as a dark line down the center of the belly. Their small body size combined with its tendency to leap away quickly when approached has made it challenging to observe individuals in the natural environment and to understand various facets of their ecology.
Range
These small frogs are native to the extreme southern tip of Texas into Mexico, within the Lower Rio Grande Valley. However, most likely due to the plotted plant trade, populations have established outside of their native range. Rio Grande Chirping Frogs have been introduced as far north as Dallas and along the Gulf Coast, and have been found in other Texas cities such as San Antonio, College Station, Corpus Christi, Houston, Kingsville, Tyler, and Nacogdoches.
Habitat and Feeding
In their native range, this species can be found in moist palm groves and thickets of underbrush. In urban areas, they are most often associated with gardens, well-watered lawns, ditches, flower beds, and rubbish piles. They are nocturnal and retreat to rocks and moist vegetative debris during the day. Little is known on their feeding ecology but some individuals have been observed consuming prey such as small spiders, flies, termites, and other insects.
Breeding and Reproduction
Breeding season for this species occurs in April and May throughout its native range when males can be heard calling both day and night. Calling activity is highest on rainy nights and when relative humidity is above 80%. The advertisements calls are soft chirps that sound similar to birds singing in the distance and are repeated multiple times at random intervals. Sometimes, they sound like short trills when the frog calls multiple times in quick succession. In the areas where non-native populations are established, breeding and calling has been documented from April-September. This species is completely terrestrial and does not require aquatic habitat for breeding. Rio Grande Chirping Frogs lack a larval stage and undergoes direct development whereby the female lays the eggs in a protected moist environment and hatch as tiny fully formed frogs.
Conservation
Though there have been declines in many amphibian species over the last few decades, the Rio Grande Chirping Frog is still common and considered abundant in the urban areas where non-native populations have established, and throughout its native range. This species is not under federal or state protection.
Pertinent References
Lasky, J., Jetz, W., and Keitt, T. 2011. Conservation biogeography of the US—Mexico border: A transcontinental risk assessment of barriers to animal dispersal. Diversity and Distributions 17:673-687.
Lutterschmidt, W.I. and M.L. Thies. 1999. Geographic distribution: Syrrhophus cystignathoides (Rio Grande chirping frog). Herpetological Review 30:51.
Wallace, E. J. 2005. Rio Grande Chirping Frog. Pp. 494-495 in M. Lannoo (Ed.), Amphibian Declines: The Conservation Status of United States Species. University of California Press, USA.
Account Author: Hailey Hester
Photos: James Childress
Edited by Christopher Schalk
Rio Grande Chirping Frogs are small bodied frogs that range from 5/8-1 inch in length, and are typically grayish-brown with olive, and sometimes yellow, undertones. They have an elongated, flattened body, with a pointed snout and long slender toes with prominent tubercles. A dark line/shadow that extends from eye to nostril is one of the more distinguishing characteristics usually present in individuals of this species. Most individuals feature dark spots randomly scattered across their back. The skin is translucent on the ventral side of the body, through which blood vessels are visible and appear as a dark line down the center of the belly. Their small body size combined with its tendency to leap away quickly when approached has made it challenging to observe individuals in the natural environment and to understand various facets of their ecology.
Range
These small frogs are native to the extreme southern tip of Texas into Mexico, within the Lower Rio Grande Valley. However, most likely due to the plotted plant trade, populations have established outside of their native range. Rio Grande Chirping Frogs have been introduced as far north as Dallas and along the Gulf Coast, and have been found in other Texas cities such as San Antonio, College Station, Corpus Christi, Houston, Kingsville, Tyler, and Nacogdoches.
Habitat and Feeding
In their native range, this species can be found in moist palm groves and thickets of underbrush. In urban areas, they are most often associated with gardens, well-watered lawns, ditches, flower beds, and rubbish piles. They are nocturnal and retreat to rocks and moist vegetative debris during the day. Little is known on their feeding ecology but some individuals have been observed consuming prey such as small spiders, flies, termites, and other insects.
Breeding and Reproduction
Breeding season for this species occurs in April and May throughout its native range when males can be heard calling both day and night. Calling activity is highest on rainy nights and when relative humidity is above 80%. The advertisements calls are soft chirps that sound similar to birds singing in the distance and are repeated multiple times at random intervals. Sometimes, they sound like short trills when the frog calls multiple times in quick succession. In the areas where non-native populations are established, breeding and calling has been documented from April-September. This species is completely terrestrial and does not require aquatic habitat for breeding. Rio Grande Chirping Frogs lack a larval stage and undergoes direct development whereby the female lays the eggs in a protected moist environment and hatch as tiny fully formed frogs.
Conservation
Though there have been declines in many amphibian species over the last few decades, the Rio Grande Chirping Frog is still common and considered abundant in the urban areas where non-native populations have established, and throughout its native range. This species is not under federal or state protection.
Pertinent References
Lasky, J., Jetz, W., and Keitt, T. 2011. Conservation biogeography of the US—Mexico border: A transcontinental risk assessment of barriers to animal dispersal. Diversity and Distributions 17:673-687.
Lutterschmidt, W.I. and M.L. Thies. 1999. Geographic distribution: Syrrhophus cystignathoides (Rio Grande chirping frog). Herpetological Review 30:51.
Wallace, E. J. 2005. Rio Grande Chirping Frog. Pp. 494-495 in M. Lannoo (Ed.), Amphibian Declines: The Conservation Status of United States Species. University of California Press, USA.
Account Author: Hailey Hester
Photos: James Childress
Edited by Christopher Schalk