hear call (196.7K WMA file)

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Country distribution from AmphibiaWeb's database: United States

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The following account is modified from Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo (©2005 by the Regents of the University of California), used with permission of University of California Press. The book is available from UC Press.

Eleutherodactylus (= Syrrhophus) marnockii (Cope, 1878a)
            Cliff Chirping Frog

J. Eric Wallace¹

            The genus Syrrhophus was synonomized with the genus Eleutherodactylus and considered a subgenus (including the genus Tomodactylus) by Hedges (1989).  But Dixon (2000) notes that this synonomy does not consider behavior, morphology, or genetic characters and so maintains Syrrhophus at the generic level.

1. Historical versus Current Distribution.  The type locality of cliff chirping frogs (Eleutherodactylus marnockii) is “near San Antonio” (Cope, 1878a).  This is further restricted to Helotes, Bexar County, Texas, by Strecker (1933).  Cliff chirping frogs are common in rocky areas of central Texas on the Edwards Plateau west to the Stockton Plateau (Jameson, 1955; Dixon, 2000).  Currently, most gaps in the distribution of cliff chirping frogs are likely from lack of survey effort.  Searches in appropriate habitats throughout their range will likely continue to increase our knowledge of their distribution (Husak, 1998; Malone, 1998) and are especially needed along the western edge of their known range—the possible contact zone with spotted chirping frogs (E. guttilatus; see taxonomic discussion under E. guttilatus account).  Fossil records exist from Edwards, Foard, Knox, and Kerr counties, Texas (Parmley, 1988a,b; Dixon, 2000) suggesting a Pleistocene distribution approximately 320 km to the north of present day populations.

            Jameson (1955) presents the only comprehensive study on the ecology of cliff chirping frogs.  His work on the population dynamics of cliff chirping frogs combines extensive field observations, intensive experimental field manipulations, and laboratory work.  Much of the information in this species account is extracted directly from there.  Dixon (2000) provides a current, comprehensive bibliography of cliff chirping frogs with notes on taxonomy.  Popular accounts in field guide format may be found in Cochran and Goin (1970), Smith and Barlow (1978), Garrett and Barker (1987), Behler and King (1989), Conant and Collins (1998), and Bartlett and Bartlett (1999a).

            For discussions of the historical and current biogeography of the subgenus (= Syrrhophus; Hedges, 1989) and for the species marnockii, see Smith and Buechner (1947), Blair (1950), Milstead et al. (1950), Morafka (1977), Duellman and Sweet (1999), and Hedges (1999).

2. Historical versus Current Abundance.  Jameson (1955) conducted population studies at 12 sites in the vicinity of Austin, Texas, and estimated population densities of cliff chirping frogs from 1.2–8.9 frogs/ac.  He attributed variation in local densities to availability and structure of rocky substrate and moisture (as evidenced by amount of vegetation).  Areas with more moisture and vegetation and greater rock structure (e.g., talus slopes and rock piles) supported denser populations.  During his research, he noted reductions in frog densities at two of his study sites and suggested disturbance by fire to be the cause in one case and road construction in the other. 

3. Life History Features.

            A. Breeding.  Reproduction is terrestrial.  Breeding occurs primarily from April–May with a second pulse during September–October; both peaks are coincident with rain events (Jameson, 1955).  Based on observations of gravid females, he suggests that breeding may take place from late February to early December.  Calling is most pronounced during the early evening following dusk and tends to diminish throughout the night; during the height of the breeding season(s), calls may be heard until dawn.  Cliff chirping frogs exhibit complex mating behaviors including preamplectic courtship and mating-specific vocalizations (Jameson, 1954).  Amplexus is axillary.  He noted what appeared to be a call hierarchy in which groups of 3–4 individuals followed the lead of a dominant male.  Fouquette (1960) provides descriptions of two types of calls produced by cliff chirping frogs.  Jameson (1955) comments on the extreme difficulty of sexing frogs in the field.  The only means was the presence of eggs observable through the stomach wall in gravid females and the vocalizations of males.  He notes that while males may mate several times/year, females may mate from 1–3 times/year.  Jameson (1955) provides additional, detailed information on breeding behaviors and general activity patterns under various environmental conditions.

                        i. Breeding migrations.  This highly terrestrial frog does not form breeding migrations or aggregations. 

                        ii. Breeding habitat.  Little is known regarding cliff chirping frog breeding microhabitats.  Frogs have been observed in amplexus twice in the wild, once on an exposed rock substrate and once in a rock crack above dry soil.  In neither case was there any moist soil nearby.  Chirping frogs in the wild continue to vocalize while in amplexus.  Jameson (1955) suggests this may be an attempt to lead the female to moist soil for egg deposition or may be necessary to instigate egg laying and/or to ensure proper fertilization.  In captivity, mating occurred only when males called females to a site with moist soil after which males did not continue to call while in amplexus.  All eggs laid in captivity were sterile (Jameson, 1955). 

            B. Eggs.

                        i. Egg deposition sites.  Egg deposition sites in nature are unknown despite considerable effort to locate them (Jameson, 1955).

                        ii. Clutch size.  In captivity, 8–20 sterile eggs were laid in trenches dug in moist soil by the female and covered by both frogs with their legs as they moved forward.

            C. Direct Development.  Larvae undergo direct development within the egg capsule and hatch as froglets into the terrestrial environment (Jameson, 1955; Lynch, 1971).  Specific information on timing and duration of development is lacking.  The incubation period for the closely related Rio Grand chirping frog (E. cystignathoides campi) under captive and experimental conditions was 14–16 d (Hayes-Odum, 1990).

                        i. Brood sites.  Unknown.

                        ii. Parental care.  Parental care occurs in some Eleutherodactylus and has been suggested to occur in barking frogs (E. augusti; Jameson, 1950b).  Because barking frogs co-occur with cliff chirping frogs in the same habitats and environmental conditions, parental care in chirping frogs requires further investigation.

            D. Juvenile Habitat.  Juvenile habitat is likely similar to adults, i.e., they require a similar physiography in the form of rocky and vegetative structure providing for cover and moist refugia.  In Jameson’s (1955) intensive study, juveniles were observed in all but the driest and coldest months (December, January) of the year, with peak activity similar to that noted for adults and coincident with moist periods.

            During a field manipulation study on dispersing juveniles, Jameson (1955) recorded an average dispersal distance of 211.4 ± 25.6 m (231 ± 28 yd) for those individuals that apparently recruited into the resident population.  He found that most juveniles dispersed parallel to available habitat (in these cases, rocky exposures) and considered time of dispersal dependent on availability of moisture and time of breeding and hatching. 

            E. Adult Habitat.  Cliff chirping frogs are saxicolous and to some extent cavernicolous in nature and are primarily found in the juniper-oak association of the Balconian Province of Blair (1950).  They are always found in association with rocks and may be found underneath and in crevices in rocks occurring along limestone ledges and bluffs, on talus slides, in ravines, and near streams (Smith and Buechner, 1947; Wright and Wright, 1949; Jameson, 1955).  Caves often support large populations (Jameson, 1955).  These frogs are primarily nocturnal with most activity recorded in the hours following dusk, especially following spring and fall rains (Wright and Wright, 1949; Jameson, 1955).  During the height of breeding season(s), individuals remain active throughout the night and males may continue to vocalize during daylight hours (Jameson, 1955).  During the day, these frogs can be found under cover objects (Wright and Wright, 1949; Jameson, 1955).  On a few occasions, Jameson (1955) observed individuals on arboreal perches from 1.2–2.4 m (4–8 ft) above the ground.

            Jameson (1955) showed that these highly terrestrial frogs are relatively incapable of swimming, as demonstrated by individuals that drowned within 2 hr of being placed in a jar of water, and attributes their inactivity during intense rainfall events to this inability. 

            F. Home Range Size.  Jameson (1955) estimated average home ranges of cliff chirping frogs during the breeding season from four distinct types of habitat.  Average home ranges by type ranged between 0.052–0.139 ac.  Size of home ranges were significantly correlated with the unique physiography of each type of site (i.e., the more structurally diverse the habitat, the smaller the home range).  Home ranges tended to be occupied throughout their lifespan (Jameson, 1955). 

            G. Territories.  Unknown.

            H. Aestivation/Avoiding Dessication.  Cliff chirping frogs may be found at nearly any time during the year if environmental conditions are appropriate.  Activity during hot, dry summer periods is generally minimal.  Jameson (1955) observed frogs at temperatures as high as about 32 ˚C (90 ˚F) but does not elaborate on activities.

            I. Seasonal Migrations.  Chirping frogs do not undertake seasonal migrations per se, however, through experimental field manipulations, Jameson (1955) showed that cliff chirping frogs will move into areas of decreased population density from areas of high population density.

            J. Torpor (Hibernation).  Activity during cold wet winter periods is generally minimal.  Jameson (1955) found that during cold, moist periods individuals could be observed in the same crevice over the course of several days.  He has observed frogs at temperatures as low as 1 ˚C (34 ˚F), but does not elaborate on their activities.

            K. Interspecific Associations/Exclusions.  Cliff chirping frogs are sympatric with barking frogs (Eleutherodactylus augusti) throughout much of their range in Texas and often share the same rocky microhabitats (Jameson, 1954; Dixon, 2000).  Cliff chirping frogs have also been found associated with Gulf Coast toads (Bufo valliceps [now considered to be Coastal-Plain toads, B. nebulifer; see Mulcahy and Mendelson, 2000; Mendelson, this volume), red-spotted toads (B. punctatus), and western slimy salamanders (Plethodon albagula; McAlister, 1954; Jameson, 1955; Hubbs and Martin, 1967).  Jameson (1955) lists several vertebrates and invertebrates that co-occur with cliff chirping frogs and might compete for prey.

            L. Age/Size at Reproductive Maturity.  Based on measurements of gravid females and calling males, frogs reach sexual maturity at 19–22 mm and 18–22 mm, respectively (Jameson, 1955).  Lynch (1970) measured 103 museum specimens and found adult males and females ranging between 18.4–28.9 and 20.4–35.4 mm, respectively.  They attain a maximum length of 38 mm (Cope, 1889).  The period of fastest growth occurs during the spring and summer (Jameson, 1952, fig. 4), and growth rates decrease as frogs become larger.

            M. Longevity.  Jameson (1955) suggests cliff chirping frogs may live ≤ 3 yr in the wild.

            N. Feeding Behavior.  Documented prey of wild cliff chirping frogs include ants, small beetles, camel crickets, termites, and small spiders (see Jameson, 1952, for more detailed information).  Captive animals also feed on a variety of insects (Jameson, 1955).  Jameson (1952) noted the interesting behavior of chirping frogs "robbing" insects entrapped in the webs of orbit web spiders (Argiopidae).

            O. Predators.  Known predators of cliff chirping frogs include western diamond-backed rattlesnakes (Crotalus atrox), mottled rock rattlesnakes (C. lepidus), copperheads (Agkistrodon contortrix), black-necked garter snakes (Thamnophis cyrtopsis), and large wolf spiders (Milstead et al., 1950; Fouquette, 1954; Jameson, 1955).  Jameson (1955) observed predation in the laboratory by barking frogs (E. augusti), Coastal-Plain toads, and tarantulas.

            P. Anti-Predator Mechanisms.  To avoid capture, cliff chirping frogs are capable of quick movements and will hop or run for the nearest cover, usually in the form of rock cracks or crevices (Jameson, 1955).

            Q. Diseases.  Unknown.

            R. Parasites.  Mites of the genus Hannemania are known ectoparasites of cliff chirping frogs (Jameson, 1952; Lynch, 1970).

4. Conservation.  Cliff chirping frogs have no federal or state conservation status.  Based on Jameson’s (1955) findings, cliff chirping frogs were common and relatively abundant in several urban areas in Austin, Texas.  This suggests an ability to cope with at least certain types of human-mediated habitat disturbance.  They are still found in city parks today (Bartlett and Bartlett, 1999a).  Resurveys at Jameson’s urban sites would provide insight into the long-term ability of this frog to persist in urban settings.

            The recent introduction of Rio Grande chirping frogs through the potted plant trade into some urban areas (e.g., San Antonio, Texas; Dixon, 2000) may place introduced frogs in direct contact with resident populations of cliff chirping frogs.  The repercussions of this interaction are unknown, but detrimental effects could include introduction of novel disease pathogens, competition, and/or hybridization.  Measures should be instituted to decrease the likelihood of further introductions.

¹J. Eric Wallace
School of Renewable Natural Resources
University of Arizona
Tucson, Arizona 85721
batrachia@yahoo.com

Citation: AmphibiaWeb. 2018. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Nov 2018.

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