Distribution and Habitat. The species ranges from southeastern New Mexico, south along the Atlantic slope through at least southeastern Mexico (Platz, 1991; Degenhardt et al., 1996; Conant and Collins, 1998; Dixon, 2000). The southern limit of the distribution is near Veracruz and frogs from farther south in the Campeche region to be Lithobates brownorum (= Lithobates berlandieri brownorum, Sanders, 1973). Frost (1982) noted populations of “berlandieri-like frogs of uncertain taxonomic affiliation” from farther south in Mexico, Guatemala, Honduras, and Costa Rica. Lee (1996) considered frogs in southwestern Campeche, Tabasco, and southern Veracruz to be L. b. brownorum, and frogs from farther south on the Yucatán Peninsula to be L. b. berlandieri.
In Arizona, Rio Grande Leopard Frogs are established on the Gila River drainage and associated croplands from Phoenix to the Colorado River confluence; they are on the Colorado River on the Arizona–California border near Yuma, Arizona; and they are in the Imperial Valley of southeastern California; and on the Rio Colorado, Sonora, and Baja California Norte, Mexico (Platz et al. 1990; Jennings and Hayes 1994b; Miera and Sredl 2000; Rorabaugh et al. 2002).
It was probably introduced in the 1960s or 1970s as tadpoles or frogs transported with warm water sport fishes from a hatchery in New Mexico or Texas (the Federal hatchery in Uvalde, Texas is the most likely source). By 1990, the species was widespread along the Gila River and in agricultural ditches and canals in the Gila River Valley from near Buckeye south to Yuma, and then along the Colorado River and adjacent agriculture areas south of Laguna Dam to the international boundary (Platz et al. 1990). The Rio Grande Leopard Frog colonized aquatic habitats unoccupied by native ranids and its appearance on the Gila and Colorado rivers likely occurred after the Lowland Leopard Frog had been extirpated (Rorabaugh 2010). Jennings (1987) found the Rio Grande Leopard Frog most abundant at sites with large, flowing springs that formed pools along the spring run. On the Yucatán Peninsula, they are “common” in virtually all freshwater habitats, but seem to reach especially high densities in open, disturbed situations (Lee, 1996).
In California and Arizona, they occur with Woodhouse’s Toads and American Bullfrogs. Surprisingly, Rio Grande Leopard Frogs appear to thrive in habitats that support limited numbers of bullfrogs (Jennings and Hayes, 1994b; Rorabaugh 2005). Rio Grande leopard frogs are found occasionally with Great Plains Toads, Sonoran Desert Toads, and Couch’s Spadefoots in Arizona (Rorabaugh 2005).
Diet. Parker and Goldstein (2004) identified prey items in the diet of Lithobates berlandieri in south and west Texas. Adult frogs were collected in the spring and fall from each of five sites in Texas. The stomach contents of 85 frogs were analyzed. Prey items identified indicate that individuals of this species, like other Ranids, are generalist, opportunistic predators whose diet is most strongly influenced by prey availability. In Texas, this species often contained small leopard frogs (Platz et al., 1990). Hernández-Austria et al. (2019) found Lithobates berlandieri was widely distributed in terrestrial habitats and had access to a variety of prey. Individuals were found in pools close to the river and on the riverbank. The diet of L. berlandieri was mostly arachnids and coleopterans (terrestrial prey). The high dietary diversity of L. berlandieri may partially explain the success of L. berlandieri in a great variety of environments ranging from tropical and temperate forests to xerophytic scrub, in a large altitudinal and latitudinal range. One L. berlandieri contained the remains of a xantusiid lizard (Lepidophyma sp.). Both prey number and volume content were higher in the dry season than in the wet season.
Movement. They have been found 1.6 km from any known water source during the summer rainy season in Arizona (Rorabaugh 2005), and after the first rains in the Yucatán Peninsula, frogs have been collected several km from water (Campbell, 1998). In New Mexico, Jennings (1987) noted collections of Rio Grande leopard frogs from intermittent water sources and suggested these were frogs that had dispersed from permanent water during wet periods.
Seasonal activity. Rio Grande leopard frogs are inactive during the cold winter; although in warmer areas they may be active year-round. In Arizona, active Rio Grande leopard frogs have been observed as early as 9 January and as late as 29 October (Rorabaugh 2005).
Predators and Defense. In New Mexico, the Checkered Garter Snake (Thamnophis marcianus) preys on Rio Grande Leopard Frog tadpoles and small metamorphs. The American Bullfrog as well as a variety of fishes are potential threats to the species (Jennings, 1987b). Crayfish, turtles, fishes, birds, small mammals, and humans prey on Rio Grande Leopard Frogs (Sanders and Smith 1971). The Predaceous Diving Beetle and the Giant Water Scavenging Beetle (Ideker,1979) are likely feeding on tadpoles whenever the opportunity presents itself. Grackles have been observed feeding on tadpoles in aggregations when they are proximate to the shoreline. Painted Turtles are also known predators on these tadpoles (Feder, 1983). Disturbed frogs and tadpoles seek shelter under rocks and vegetation during the day (Degenhardt et al. 1996, Rorabaugh 2005). A burst of rapid swimming is used by tadpoles to avoid turtles (Feder, 1983b).
Diseases. A die-off of Rio Grande Leopard Frogs at a pond near Phoenix was attributed to “red-leg,” a Pseudomonas infection (Sredl in Rorabaugh 2005).
Parasites. Two species of mites of the genus Hannemania were found on Rio Grande Leopard Frogs in Big Bend National Park, Texas (Jung et al., 2001). Trematodes (digeneans) were found by Guillen-Hernandez et al. (2000) in frogs collected from Los Tuxtlas, Veracruz, Mexico; and a tetrathyridia tapeworm (Mesocestoides sp.) was found in the liver and mesenteries of a single specimen from Texas (McAllister and Conn, 1990).
Conservation. Its introduction into Arizona is unwanted but no negative impacts have yet been documented. It is not sympatric with any other leopard frogs in the state. Rio Grande Leopard Frogs have no status under the EAS or CITES but are considered a Species of Special Protection by the Mexican Government (Secretaria de Desarrollo Social, 1994). The species is not considered of Special Concern, Threatened, or Endangered by any of the USA states it occurs in.
Taxonomy. Baird (1859,2:27) described Rana berlandieri based upon twelve syntypes USNM 3293 (nine specimens), USNM 131513, MCZ 155 (two specimens). Pace (1974) designated USNM 131513 the lectotype from Southern Texas, corrected to Brownsville, Texas by Kellogg, (1932:205). Cope (1875:32) used the combination Rana halecina berlandieri, Cope (1886:517:1-35) described Rana halecina austricola based upon the syntypes Girard (1859) had examined and an illustration by Brocchi (1881:10) that he had labeled “Rana lecontei.” Kellogg, 1932:207-08), used the illustration as a lectotype and the type locality was given as Mexican specimens referred to in these publications and designated as “Vera Cruz”, Mexico. Smith and Taylor (1950:351) designated the type locality as Matamoros, Tamaulipas, Mexico. Cope (1889:398) used the combinations Rana virescens austricola and Rana virescens berlandieri. Ives (1891: 461) used the combination Rana virescens var. austricola. Ruthven (1912:305) used the combination Rana austricola but this may not have been based on R. berlandieri according to Noble (1918:315). Boulenger (1919:413) used the combination Rana halecina var. austricola. Schmidt (1941:487) used the combination Rana pipiens berlandieri. Smith (1947:409) used Rana pipiens austricola. Sanders (1973: 87) used Rana berlandieri berlandieri. Dubois (1987 “1986”: 41) used Rana (Rana) berlandieri. Dubois (1992: 835) used Rana (Pantherana) berlandieri. Hillis and Wilcox (2005:305) used Rana (Novirana, Sierrana, Pantherana, Scurrilirana) berlandieri considered an invalid name formulation under the International Code of Zoological Nomenclature (1999) as discussed by Dubois (2007:395). They (Hillis and Wilcox, 2005:305) also used Rana (Novirana) berlandieri. Frost et al. (2006:369) placed the species in the genus Lithobates, using Lithobates berlandieri. Dubois (2006:42) Lithobates (Lithobates) berlandieri. Hillis (2007:335) used the combination Rana (Scurrilirana) berlandieri by implication. Fouquette and Dubois (2014:403) used Rana (Lithobates) berlandieri.
Zaldı́var-Riverón et al. (2004) examined the phylogenetic relationships among specimens from 25 different locations for the six Mexican coastal leopard frog species of the Rana berlandieri species group. Most of the clades recovered by both tree building methods were strongly supported, but conflicting clades recovered by each analysis are generally poorly supported. Both analyses (maximum parsimony and Bayesian analyses) reject the previously proposed subgroupings of the R. berlandieri species group.