Amphibians of North Carolina

Scientific Name:	Common Name:		Family (Alpha):

Hylidae Members:
Acris crepitans - Eastern Cricket Frog

Taxonomy

Class: Amphibia

Order: Anura

Family: Hylidae

Subfamily: Hylinae

Other Common Name(s): Northern Cricket Frog


Taxonomic Comments: Acris is a genus of small hylid frogs that is endemic to North America. Two species have traditionally been recognized, each with formally recognized subspecies. Acris gryllus is a southern form with two subspecies, while Acris crepitans is a more northern and western form with three subspecies. After analyzing geographic variation in both nuclear and mitochondrial DNA, Gamble et al. (2008) retained A. gryllus as a valid species, but split A. crepitans into two species. These are Acris blanchardi, which was formerly considered to be a mid-western subspecies of A. crepitans (A. c. blanchardi), and A. crepitans (sensu stricto), which contains most other populations in the eastern US. They further recognized an eastern and western clade within A. crepitans (sensu stricto), and did not recognize any of the previously described subspecies. North Carolina populations were not included in the analysis, but they are presumably members of the eastern clade. Although very similar is general appearance to A. gryllus, North Carolina populations of A. crepitans are clearly a distinct species based on DNA markers, morphology, vocalizations, and ecology (Gamble et al. 2008; Micancin 2008, Micancin and Mette 2009, Micancin et al. 2014, Nevo and Capranica 1985). The two species co-exist at several sites in the Fall-zone and Coastal Plain without any evidence of interbreeding.
Species Comments: Much of our knowledge of the natural history of A. crepitans (sensu lato) was based on studies of a western subspecies, A. c. blanchardi. This form has since been elevated to full species status, which has left many gaps in our knowledge of the life history of A. crepitans (sensu stricto).

Identification

Description: Acris crepitans is a small frog that is very similar to A. gryllus and best identified by considering voice characteristics, range, and morphological features. The adults are small, slender frogs with a blunt snout and a black line on the posterior portion of the thigh. The black line is usually very irregular and not sharply defined, and the lower area of the thigh often has black stippling that is suggestive of a second line (Beane et al. 2010, Dodd 2013). The webbing of the hind feet is extensive (Conant and Collins 1998) and there is usually a pair of prominent, white anal tubercles between the back legs. The skin is noticeably rugose with small bumps and warts on the back, sides, and upper surfaces of the legs. The dorsal ground color is highly variable and can be gray, tan, light brown, or olive (Dodd 2013). The most conspicuous mark is a diffuse, broad mid-dorsal stripe that can be gray, red, brownish red or green. It extends anteriorly from the urostyle, then forks just beyond the insertion of the front legs, with each branch leading towards an eye. A dark triangular mark that is of the same general ground color as the body is nested within the fork and points caudally. Beyond this -- and between the eyes and the snout -- is another area of light coloration that often matches the coloration of the mid-dorsal stripe. The sides of the body and dorsal surfaces of the legs are often overlain by several oblong darker blotches or bands. A relatively large and conspicuous blotch is usually present on the lower side about midway between the front and hind legs. The undersides of the legs and body are white. Many specimens in North Carolina are rather uniformly colored above and often lack some or all of the Y-shaped patterning and triangular mark on the head. So, expect deviations from the general description above. The male has a yellowish to grayish-yellow vocal sac during the breeding season. At other times of the year it appears as a series of folds on the throat rather than a sac. The adults vary from 16–35 mm SUL and the males average about 10% smaller than the females based on SUL. The adult typically average around 20-26 mm in most populations. Micancin and Mette (2009) reported a mean of 21.6 mm SUL for North Carolina specimens, while (Mitchell 1986) recorded a means of 23 mm and 26 mm for males and females in Virginia. This species is easily confused with A. gryllus. In general, A. gryllus is slightly smaller and more slender, has a more pointed snout, longer legs, and less webbing between the toes (Conant and Collins 1998). It also has a more narrow and sharply defined black stripe on the thigh, and poorly developed anal tubercles (Beane et al. 2010, Dodd 2013). Micancin and Mette (2009) analyzed museum specimens from North Carolina and found that the diameter of the anal tubercles and the extent of webbing on the fourth (longest) toe on the hind foot are the best morphological traits for distinguishing preserved specimens of A. crepitans and A. gryllus. At sites where these species occur syntopically the texture of the skin, the appearance of the thigh stripes, and the degree of development of the anal tubercles are the most useful field traits. The thigh stripes of A. crepitans are broader and have a more mottled appearance than A. gryllus, as if they had been drawn with a charcoal pencil. The thigh stripes of A. gryllus are narrower and less jagged, as if painted with a fine watercolor brush. If the males are calling, voice characteristics can be used to identify the species. Both species make clicking notes that resemble two small stones being tapped together. To the human ear, the advertisement call of A. crepitans consists of a series of somewhat raspy clicks. The intervals between clicks usually decrease with time and often end in a rapid, rattling sequence at the end. The clicks of A. gryllus are more metallic and crisper sounding. They also tend to accelerate with time but do not end in as rapid of a rattling sequence. We recommend making recordings in regions of the state where the two are sympatric and analyzing patterns using sound analysis software for positive identifications (see Micancin and Mette 2009). Additional information on sound characteristics are below. In addition to morphological traits, specimens in North Carolina can often be assigned to species based on geographic locality. Populations in the northern half of the Fall Zone, almost all of the northern half of the upper Coastal Plain, most areas of the Piedmont, and the mountain valleys are all assignable to A. crepitans (Micancin 2008, Micancin and Mette 2009). Populations in some areas of the lower Coastal Plain and the Sandhills region could be either species and need additional evidence such as voice or morphological characteristics to assign to species. Acris gryllus was previously present in the northern half of the Fall Zone and the northern half of the upper Coastal Plain, but now appears to be absent from almost all of this general region based on field surveys (see Micancin 2008, Micancin and Mette 2009, and Micancin et al. 2012 for distribution maps). The tadpoles are medium-sized, with grayish to greenish bodies above. They have long tails with low tail fins that are lightly mottled with tan and scattered black flecks. Many tadpoles are easily distinguished by their conspicuous black tail tips, although some tadpoles lack these. There is a light stripe bordered by dark stripes along the side of the snout, and the throat is light with a dark band extending across the chest (Dodd 2013). Large tadpoles range from 30-46 mm TL but are usually around 25 mm. The mature tadpoles are markedly larger than the froglets that emerge at metamorphosis.
Vocalizations: To the human ear, the advertisement call consists of a series of clicks in which the interval between clicks decreases with time and often ends in a rapid, rattling sequence at the end. The individual clicks have a dominant frequency of about 3.55 kHz, an average duration of 159 ms (range 92 to 241 ms), an average of 5.5 pulses (range 3.9 to 7.1) per click, and an average interpulse interval of 16 ms (range 11 to 21 ms; Micancin and Mette 2009). The songs of both of our species of cricket frogs consist of series of clicks, often described as "gick" "gick" "gick" and likened to pebbles, marbles, or ball-bearings being struck together. There are some differences that are detectable in the overall pattern of these clicks, but the clearest diagnostic difference can be seen in the structure of the individual clicks. As shown by Blair (1958), Nevo and Capranica (1985), and Micancin (2008), the clicks of both species actually consist of a series of pulses rather than a true click (a vertical bar on a spectrogram or oscillogram). In Acris gryllus, these pulses are arranged in a tight sequence with a decline in amplitude from beginning to end. In A. crepitans, the pulses are often longer in duration and divided into two or more well-spaced groups that are usually uniform in amplitude and do not decline from beginning to end (see Figure 1.2 in Micancin 2008).
Online Photos: Google iNaturalist
Observation Methods: Cricket frogs are most easily seen by walking the margins of permanent aquatic habitats such as ponds, freshwater marshes or the shallow sections of small lakes. They often respond to approaching humans by diving into the water, them swimming back towards the shore.

Download Video: "MP4"
AmphibiaWeb Account

Distribution in North Carolina

Distribution Comments: Acris crepitans occurs from southern New York southward along the Atlantic Seaboard through Georgia, Alabama, the Florida Panhandle and Mississippi to southeastern Louisiana, then northward through Tennessee and Kentucky to the Ohio River. It is rare in the southern Appalachians and occurs only sporadically in the lower Coastal Plain of the Carolinas and Georgia. Populations in North Carolina are most common in the eastern Piedmont and Upper Coastal Plain, but populations have occasionally been found farther east along some of the major river floodplains and associated swamplands. It is known from a few scattered localities in the western Piedmont, and we have a few historical records from the lower valleys in the central and southern Blue Ridge.
Distribution Reference: Dodd (2013)
County Map: Clicking on a county returns the records for the species in that county.


GBIF Global Distribution

Key Habitat Requirements

Habitat: The adults and juveniles are typically found in the immediate vicinity of semipermanent and permanent wetlands during the warmer months of the year. They generally prefer sunny or lightly shaded habitats such as those found along the margins of farm ponds, beaver ponds, marshes and lake shores. Sites with shallow water, floating mats of aquatic vegetation, gently sloping muddy banks, grassy areas along the shorelines, and nearby forest appear to offer ideal conditions. Individuals rarely move far from bodies of water during the warmer months of the breeding season, and are often found on land on moist substrates at or within a few meters of the shoreline. When in the water individuals often rest on algal mats, piles of decaying leaves, and floating aquatic vegetation. They can also be found along the margins of slow-moving streams and flooded ditches with little water flow. Overwintering typically occurs in forested habitats that surround the breeding sites. Bottomlands and swamplands are frequently used in the southern portion of the range (Bayless 1966, 1969b). Krysko et al. (2019) noted that populations in the Florida Panhandle are typically found in closed-canopy forests, including deciduous, mixed pine-hardwood, and bottomland forests.

Most populations in North Carolina occur in the Piedmont and Fall Line where they frequent farm ponds, shallow, vegetated zones of small lakes, beaver ponds, roadside ditches, freshwater marshes and other suitable habitats. They also occur along some of the river floodplains flowing eastward through the Coastal Plain (Micancin and Mette 2009). In contrast to the Southern Cricket Frog that is associated primarily with blackwater habitats in the Coastal Plain, the eastern Cricket Frog occurs mostly in brownwater river systems, which may reflect a lower tolerance for acidic waters. Exceptions occur in the Chowan River Basin, where the two species sometimes share breeding sites. More work is needed to clarify the specific habitat associations of both species in North Carolina (Micancin and Mette 2009).

Environmental and Physiological Tolerances: This species is rarely found in highly acidic waters (Mecham 1964) and was the least acid-tolerant species that was tested by Gosner and Black (1957a). Survivorship of eggs can be affected by a pH as high as 5–5.2, while a pH below 4.2-4.6 is usually lethal. The larvae also perform poorly in acidic waters (Sparling et al. 1995).

Biotic Relationships: The larvae share ponds with numerous aquatic predators such as odonates, diving beetles, and fishes. They are presumed to be palatability to fishes based on the fact that two closely related species (A. gryllus; A. blanchardi) appear to lack chemical defenses against fishes (Ade et al. 2010, Kats et al. 1988). They are very likely palatable to other aquatic predators such as odonates, diving beetles and newts. The larvae often have bold black tail tips that likely function to draw attention away from critical body parts such as the head.

The juveniles and adults are undoubtedly taken by numerous predators, including fishing spiders, fishes, bullfrogs, snakes, turtles, birds and mammals that frequent shorelines or live in the water (Dodd 2013). They are excellent jumpers, and characteristically make long, quick leaps with rapid zig-zagging directional changes if disturbed. One common escape strategy is to jump directly into the water and hide on the bottom or among dense vegetation. Adults also may assume a death-feigning posture where they float motionless in the water with their bellies up (Dodd 2013).

See also Habitat Account for General Brownwater Shorelines

Life History and Autecology

Breeding and Courtship: The adults begin breeding with the spring warm-up and continue into the summer months. Males in southern populations such as Alabama and Louisiana normally begin calling in March (Mecham 1964, Mount 1975), but not until late April or May in Virginia, West Virginia, and New York (Bayne 2004, Dodd 2013, Gibbs et al. 2007, Green and Pauley 1987, Mitchell 1986). Males can be heard calling in North Carolina beginning in mid to late April.

The males often begin calling a few weeks before egg deposition, which typically occurs from spring through early summer (Dodd 2013). They may continue calling sporadically into the autumn months, and may call year-round in Florida (Krysko et al. 2019). Calling typically occurs on land close to the water's edge and in West Virginia begins when daily air temperatures exceed 12°C (Bayne 2004). When at the breeding site, the adults move very little from one part of the pond to another (Dodd 2013). It is uncertain if the males stake out territories along the pond margins during the breeding season. Females that are attracted to calling males are amplexed near the front legs (axillary amplexus) and begin laying shortly thereafter.

Reproductive Mode: The females oviposit in shallow water. They deposit the eggs singly and in small masses of 2-20 eggs or so, either directly on the pond bottom or attached to vegetation and other support structures. Clutch sizes are poorly documented, but are generally thought to be around 200-400 eggs based on studies of closely related species. Bayne (2004) counted between 50–400 eggs per total clutch in captive West Virginia specimens. Hatching occurs within a few days to a week following deposition.

Aquatic Life History: Very little is known about the larval ecology (Dodd 2013). The larval period is reported to lasts 40-50 days in Louisiana (Bayless 1966) and around 50-90 days in New Jersey, with transformation in August and September (Black and Gosner 1957b). The mature tadpoles can reach 4.6 cm TL, but are more commonly around 2.5 cm TL. There is a dramatic reduction in size at metamorphosis. Wright and Wright (1949) reported that metamorphs are 9–15 mm SUL, while recent metamorphs averaged around 13 mm SUL in New York (Feliciano 2000).

Terrestrial Life History: The young metamorphs disperse away from shallow wetlands during rainy weather and move towards damp locations in terrestrial habitats (Dodd 2013). They often move to habitats near springs or along small streams flowing through woodlands. They may also move to nearby ponds or lakes using streams and rivulets as dispersal corridors. In southern locales, individuals often move to swampy bottomland forests that retain moisture during the summer and autumn. Overwintering occurs in these habitats, and often in muddy areas of the bottomlands.

The juveniles and adults in New York also overwinter on land, then move back to aquatic sites with the onset of warmer spring weather. Gibbs et al. (2007) reported that individuals overwinter within 100 m of the breeding sites, but Kenney and Stearn (2015) noted that individuals are commonly observed more than 300 m from the nearest breeding habitat in September and October. They use a wide variety of habitats while on land, including dry uplands. Kenney et al. (2012) tracked three individuals and found that they overwintered in underground animal burrows.

Individuals at northern locales are most active from early spring through autumn, while populations in the southernmost populations are active year-round except during unusual cold spells (Dodd 2013, Krysko et al. 2019). The juveniles and adults subsist on small invertebrates, including collembolans, beetles, true bugs, aphids, termites, ants, adult flies and fly larvae, spiders, mites and a variety of other larval and adult insects (Bayless 1969b, Dodd 2013). The newly emerged metamorphs become sexually mature within a few months after metamorphosing and populations appear to rapidly decline by the end of the growing season (Dodd 2013). Populations appear to experience nearly complete population turnover annually (Dodd 2013).

General Ecology

Population Ecology: Local populations often consist of hundreds of adults. One population along a 150 m transect in New York was estimated to consists of 628 frogs (range 343-1,681), while a second in the Florida Panhandle was estimated as 259 frogs (range 217 to 313) along two 150 m transects (Feliciano 2000). Those near the northern limit of the range in New York often contain < 50 calling males (Gibbs et al. 2007).

Community Ecology: A. gryllus and A. crepitans overlap geographically in some areas of their ranges, but tend to have difference habitat preferences where they occur sympatrically (Dodd 2013). Where they do share a pond, Bayless (1966, 1969b) found that individuals show evidence of microspatial segregation to some extent. The extent to which these species compete where they share ponds needs additional study.

Adverse Environmental Impacts

Status in North Carolina

NHP State Rank: S5

Global Rank: G5

Status Comments: Acris crepitans has declined in some areas of its range (Micancin et al. 2012), but populations appear to be relatively stable in North Carolina. We have several older records from the western Piedmont and mountain valleys, but almost no records in recent years.

Photo Gallery for Acris crepitans - Eastern Cricket Frog		13 photos are shown.
	Recorded by: Matt Perry Yadkin Co.	Recorded by: Steve Hall, Pat Coin, David George, and Mark Basinger Chatham Co.
	Recorded by: Stephanie Willis Chatham Co.	Recorded by: Stephanie Willis Guilfrod Co.
	Recorded by: David George, Steve Hall, Carol Tingley Chatham Co.	Recorded by: Travis McLain Anson Co.
	Recorded by: Stephanie Willis Randolph Co.	Recorded by: Travis McLain Gaston Co.
	Recorded by: J. Mickey Surry Co.	Recorded by: Steve Hall Orange Co.
	Recorded by: Owen McConnell Durham Co.	Recorded by: Owen McConnell Durham Co.
	Recorded by: Steve Hall Orange Co.

Acris crepitans - Eastern Cricket Frog

Photo Gallery for Acris crepitans - Eastern Cricket Frog

13 photos are shown.