Amphibians of North Carolina
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NC Records

Pseudacris ornata - Ornate Chorus Frog

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Taxonomy
Class: Amphibia Order: Anura Family: Hylidae Subfamily: Hylinae
Taxonomic Comments: Degner et al. (2010) analyzed mtDNA variation and recognized three clades that occur across the geographic range of this species. These include a northern clade in North Carolina, a central clade from central South Carolina to central Georgia, and a southern clade in the remainder of the range. Divergence times between the groups are around 2-3 million years ago, with the North Carolina forms splitting from the central-southern group an estimated 2.8 million years ago.
Species Comments:
Identification
Description: Adults of the Ornate Chorus Frog are small, somewhat stout-bodied frogs that are boldly marked with dark brown or blackish patches or bars. The dorsal ground coloration can vary from a rare bright green form to various shades of tan, gray, pinkish, red, or chestnut brown. A bold blackish line or bar extends from the tip of the snout through the eye to the shoulder region. It tends to be narrow between the snout and eye, then broadens between the eyes and the shoulder region. From there, it may either extend as a continuous bar along the side to the groin area, or be broken -- leaving a bold, oblong blotch near the groin area (Dodd 2013, Glorioso 2010, Jensen et al. 2008). The bars or blotches are often thinly margined by pale cream or yellowish coloration. Many specimens have a triangular mark between the eyes, and a small circular blotch is often present just above the groin. Additional bold blotching is often present on the back, and well-developed bars are usually present on the dorsum of the front and back legs. The chest and belly are cream colored to whitish, and the concealed portion of the groin and hind limbs are bright yellow. The adults are capable of lightening or darkening their colors to better match their backgrounds.

The males have dark throats during the breeding season and average slightly smaller than females. Males that were collected by Caldwell (1987) in South Carolina varied from 31-35 mm SUL (mean = 34.6 mm) versus 33-40 mm (mean = 36.2 mm) for females. Jensen et al. (2008) reported a range of 25–39 mm SUL for males and 28–40 mm for females in Georgia, and Beane et al. (2010) list a size range of 25-38 mm for specimens in the Carolinas and Virginia.

The tadpoles have laterally displaced eyes and a reddish-brown body with light dorsolateral lines that extend from the snout along the length of the body (Glorioso 2010, Gregoire 2005). The dorsal fin is highly arched, has scattered black dots, and extends forward along the body to near the eyes. The dark tail musculature is bisected by a light gold or brassy stripe that passes onto the dorsum of the body (Dodd 2013). The throat is unpigmented and the belly is light colored.
Vocalizations: The advertisement call is a very sharp metallic 'kik' that is produced in long, equally spaced repetitive sequences: “kik-kik-kik-kik-kik-kik.” Some have described it as resembling the call of a Spring Peeper (P. crucifer) but not as musical and shorter, while others have likened it to a hammer striking a steel chisel repeatedly (Dodd 2013, Jensen et al. 2008). Call characteristics are temperature dependent, but each call (“kik") is very brief (0.03–0.06 sec), and is issued about 1.5-2.5 times per second (Blair 1958a, Dodd 2013, Gerhardt 1973, Harper 1937). The longest sequence that was documented by Gerhardt (1973) consisted of 91 sequential calls. In addition to the advertisement calls, Brown and Means (1984) reported that the adults sometime make brief calls while in underground burrows. The exact function of these calls is unknown.
Technical Reference: Dodd (2013)
Online Photos:    Google   iNaturalist
Observation Methods: The adults are secretive and are best observed during the breeding season when they are at the breeding sites. They can occasionally be found crossing roads on rainy nights.
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: This is a Coastal Plain species, with the range extending from east-central North Carolina southward to central Florida, and westward through southern Georgia, portions of central and southern Alabama, and extreme southern Mississippi to the Florida Parishes of southeastern Louisiana. Populations in North Carolina extend from Beaufort County and vicinity southward to the South Carolina line.
Distribution Reference: Beane et al. (2010), Dodd (2013), Glorioso (2010)
County Map: Clicking on a county returns the records for the species in that county.
GBIF Global Distribution
Key Habitat Requirements
Habitat: The juveniles and adults are primarily found in the pine flatwoods, pine barrens and sandhills of the southeastern Coastal Plain. They also can be found in xeric hardwood hammocks, as well as more mesic pine and pine-hardwoods forests (Dodd 2013, Krysko et al. 2019). Populations are occasionally found in old fields and ruderal habitats. The adults burrow, and sandy or otherwise friable soils are essential components of the adult habitats.

Breeding typically occurs in seasonal or semipermanent habitats that are either fish-free or lack large predatory fish (Eason and Fauth 2001). Examples of natural habitats include seasonal ponds, marshes, sinkhole ponds, Carolina Bays, and gum and cypress ponds. Artificial habitats such as borrow pits, flooded fields, and roadside ditches are occasionally used, but ditches are generally used less by this species than other Pseudacris (Dodd 2013, Eason and Fauth 2001, Jensen et al. 2008, Krysko et al. 2019). This species prefers sunny habitats with little canopy cover (Gordon et al. 2013), but will use partially shaded or fully shaded sites.

In North Carolina the Ornate Chorus Frog is associated with Longleaf Pine-dominated habitats that contain isolated, ephemeral ponds. The adults are mainly fossorial and spend most of their lives in the woodlands that surround these pools. Their fossorial behavior may be an adaptation for living in Longleaf Pine communities that are fire-maintained and that historically were exposed to burns from summer thunderstorms.
Biotic Relationships: The larvae occupy seasonal ponds that tend to accumulate predators as a function of the duration of the annual hydroperiod. Ambystoma larvae, newts, and aquatic insects undoubtedly take many larvae at sites with long hydroperiods. The larvae appear to be highly vulnerable to predatory fishes and are largely restricted to fish-free habitats. The Panhandle Crayfish (Procambarus evermanni) commonly shares breeding pools with the larvae. Chandler et al. (2016) found that this species is an effective predator -- at least in laboratory tanks -- and that the addition of artificial cover does not significantly affect predation rates. Tail injuries were common in many of the attacks.

Although the adults avoid predators by burrowing, they are eaten by the Southern Hognose Snake (Neill 1952), which may seek them out in their burrows. Burrow et al. (2021) reported that the young metamorphs are vulnerable to predation from a native ant (Dorymyrmex smithi). This species is relatively uncommon in intact natural forests where it often coexists with numerous other ant species. Unfortunately, it is often the dominant species at sites where there has been historical alterations of the soils and fire regimes.
See also Habitat Account for Longleaf Pine Woodlands with Isolated Pools
Life History and Autecology
Breeding and Courtship: The Ornate Chorus Frog typically breeds from November through April, with most breeding concentrated in the winter months. The adults move to and from the breeding sites on rainy nights (Brown and Means 1984, Pechmann and Semlitsch 1986, Todd and Winne 2006) and calling has been heard as early as late October in Florida (Brown and Means 1984, Carr 1941a). Calling in most populations generally does not get underway until well into November or later. Breeding in Georgia can occur anytime from November through March, but peaks in January and February (Jensen et al. 2008). Other reports include breeding from November to April in Louisiana and South Carolina (Caldwell 1987, Dodd 2013, Dundee and Rossman 1989, Pechmann and Semlitsch 1986, Semlitsch et al. 1996). Breeding in North Carolina normally occurs from December through March.

In her detailed studies of two pond populations in South Carolina, Caldwell (1987) found that the males tended to arrive shortly before the females and stayed longer in the ponds. Males stayed an average of 23-32 days versus 14-20 days for females depending on the pond and year. The sex ratios of males and females that entered the ponds did not deviate from 1:1, but operational sex ratios were generally biased towards males due to their longer stays in the ponds. Oddly, very little breeding activity occurred during one year when heavy rains kept the ponds full. Most females that entered left without ovipositing, which suggests that annual pond drying is important for stimulating females to oviposit.

Once males arrive at the breeding sites they set up calling stations in shallow water habitats. Harper (1937) observed them calling from logs just above the water line and from grass clumps in shallow water where they often perched just a few centimeters above the water surface. Individuals may call while either floating and clinging to mats of decaying vegetation and debris, or while sitting upright (Dodd 2013). Most of the males that were observed by Gerhardt (1973) in Georgia and South Carolina were calling out of water, either at the pond edge or while perched no more than 10 cm above the water surface. Most calling occurs after dark, but individuals will call during the day -- particularly during exceptionally warm days or during cloudy or rainy weather (Dodd 2013, Harper 1937). Choruses can be heard as far as 640 m away, and both chorusing and mating is most intense following rain events (Dodd 2013, Gerhardt 1973, Harper 1937). Calling can occur when air temperatures are as low as 3°C, but active choruses are most commonly heard when temperatures are 5-10°C or higher (Gerhardt 1973, Harper 1937).

Social interactions related to calling are poorly documented. Harper (1937) noted that the males tended to space out, but it is not known if they possess calling territories. Females are attracted to the male calls (Gerhardt 1973), but it is uncertain to what extent they use individual call characteristics when selecting mates. Egg laying presumably begins within a few hours after a male amplexes a female.
Reproductive Mode: Each female attaches a series of small egg masses to grasses, sedges, or other support structures. The masses are loose and sticky, and debris readily adheres to them (Dodd 2013). Most masses that were examined by Seyle and Trauth (1982) from Georgia had 20–40 eggs (range = 21-106), while Dundee and Rossman (1989) reported a range of 6–100 eggs per mass in Louisiana. The freshly laid eggs are brown above and cream to white below and are surrounded by a single jelly envelope. They average 0.95 mm in diameter (range 0.9 -1.0 mm) and the envelopes vary from 3.6–4.2 mm in diameter. The embryos develop rapidly and typically hatch within a week. Seyle and Trauth (1982) found 214-848 eggs (mean = 443) in gravid females from Georgia.
Aquatic Life History: Most aspects of the larval life history are poorly documented. The larvae are presumably palatable to aquatic predators -- as are most species that use seasonal ponds -- but details are lacking. Individuals that breed very early may avoid many aquatic predators, but cold water temperatures can compromise growth and development and lead to higher mortality (Harkey and Semlitsch 1988). There is little data on growth rates and length of the larval period in native populations.

The tadpoles presumably graze on algae, decomposing leaves, and other aquatic vegetation and reach a maximum length of 23–43 mm TL (Dodd 2013). Jensen (2022; AmphibiaWeb) noted that the larvae are most readily found by dip-netting in submerged and emergent vegetation. Burrow and Maerz (2021) grew tadpoles in outdoor pools where they manipulated shading and the types of leaf litter that served as a food base. Survival was not strongly affected by shading and litter treatments. However, growth parameters such as growth rates and size at metamorphosis were, with larvae performing relatively poorly in conditions that simulated closed canopies with hardwood leaf litter.

Data from Caldwell (1987) based on captures at drift fences suggests a larval period of 2-3 months, but it is uncertain how long the metamorphs remained at the pond margin before dispersing towards upland habitats. Other reported values from generic accounts suggest a larval period of 3-4 months (Dodd 2013, Dundee and Rossman 1989, Jensen et al. 2008). Wright and Wright (1949) reported that the metamorphs vary from 14–16 mm SUL, but newly metamorphosed froglets that were collected by Caldwell (1987) at one site were 18.5-22.5 mm SUL (mean = 20.3 mm), while those at a second were 18-21 (mean = 19.5 mm). Other reported values are 14–16 mm SUL for Georgia specimens (Jensen et al. 2008) and 11–17 mm SUL from other sources (Dodd 2013).

Semlitsch et al. (1996) conducted a long-term (16-year) study of annual breeding population size and juvenile output of several species at a Carolina Bay in South Carolina. The pattern for P. ornata was similar to that for other species in that the successful production of juveniles was strongly influenced by pond hydroperiod, and secondarily by the presence of competitors and predators. During years with very short hydroperiods recruitment was at or near zero, while in years with long hydroperiods competition and predation played a significant role in reducing juvenile output. All of the species showed episodic recruitment, with many failures across years, and bumper crops being produced only occasionally. Per capita recruitment of juvenile P. ornata was highest in years with intermediate hydroperiod lengths. This likely reflects a trade-off between premature pond drying and the build-up of competitors and predators in ponds. In a related study, Pechmann et al. (1989) found that juvenile recruitment was most strongly correlated with the size of the female breeding population.
Terrestrial Life History: The juveniles and adults commonly live in sandy, xeric habitats and survive dry conditions by being fossorial. Brown and Means (1984) made detailed observations of individuals in captivity that were in tanks filled with sand. The frogs burrowed mostly by using synchronized strokes of the forelegs that were similar to the breaststroke of a swimmer. The back legs were used occasionally to push the upturned sand behind the frog and occasionally to help construct burrows. The frogs created several types of excavations that included shallow depressions, shallow sloping pits, and deeper tunnels that extended as deep as 10 cm. These were constructed at night when observers were not present, so the exact means of construction are unknown. Once constructed, the frogs either rested at the ends of deep tunnels or at the entrances of sloping pits that were shallower. Individuals also constructed hollow cavities without entrances where they remained for long periods of time. The animals spent most of their time in underground retreats during the two-month observation period.

The adults and juveniles are rarely seen outside of the breeding season, which suggests that they remain in burrows during most of the summer months. Deckert (1915) dug them out of Sweet Potato hills in his garden, and Neill (1952) found them buried at the base of wire grass clumps. Recently metamorphosed animals have been found beneath logs and bark on the ground (Harper 1937). Burrow et al. (2021) found that young metamorphs in field cages mostly remained beneath ground, but sometimes surfaced an hour or two before dark when conditions were humid and fed. The adults presumably also emerge occasionally at night to feed during rainy weather (Brown and Means 1984), but detailed observations are lacking.

Females often remain for two or three weeks or more at the breeding sites after ovipositing (Caldwell 1987). This suggests that they may forage heavily at the ponds before returning to upland habitats. Individuals are presumed to be generalist predators like most frogs, but detailed dietary studies are lacking. The young metamorphs appear to only remain a short time at the breeding sites before dispersing to uplands. Brown and Means (1984) captured 42 young metamorphs 20 m from the edge of a breeding pond in late April and several others 200–370 m upslope from the pond in mid May of the same year. The adults were found as far as 425–480 m from the water's edge. Palis and Aresco (2007) trapped adults as far as 200 m from a study pond in Florida, which is the greatest distance that drift fences were set from the pond margin.

Metamorphs that were marked by Caldwell (1987) appeared to reach sexually maturity in less than a year and bred for the first time the winter following metamorphosis. Annual mortality was high (generally > 90%) in years when breeding occurred, and males tended to suffer higher mortality than females when at the breeding sites. Mortality was lower in years when individuals skipped breeding due to low water levels. Most individuals breed only once during their lifetime, with perhaps a very small percentage breeding twice.
General Ecology
Population Ecology: Local populations are centered around the breeding sites, and most populations appear to consist of several hundred adults or less when averaged across several years. Gerhardt (1973) noted that the maximum chorus size at numerous sites that he surveyed in Georgia and South Carolina were around 40 males on a given night. Semlitsch et al. (1996) collected around 1600 adults at a Carolina Bay over the course of 16-years. Given the short life expectancy of this species -- with most adults breeding only once during their lifetime -- the average population size during any given year was much smaller. The maximum number of adults that were trapped by Erwin et al. (2016) in Florida during a multiyear study was 282. Population sizes of this and many other seasonal-pond breeders can fluctuate markedly (e.g., Erwin et al. 2016, Semlitsch et al. 1996), a phenomenon that is likely due to exceptional years when large numbers of juveniles are produced, and other years when there can be zero recruitment.

The extent to which local pond populations are connected via dispersal is poorly documented, but the juveniles and adults are capable of moving relatively long distances from the breeding ponds. This likely reflects their need to find suitable sandy sites for burrowing in upland habitats. Brown and Means (1984) recorded dispersing juveniles and adults moving hundreds of meters away from breeding ponds, with the greatest distances at 425–480 m.

Degner et al. (2010) examined microsatellite variation across the range and found moderate to high allelic differentiation between distant pairings. They also found evidence for fine scale population genetic structure, but it was not as strong as one might expect if populations were strongly philopatric. Their data suggests that substantial gene flow is occurring -- or has historically occurred -- among local and regional populations. More detailed fine-scale analyses of genetic structure are needed to determine population organization at different spatial scales.

Community Ecology: The larvae commonly share breeding ponds with numerous other amphibians, including both potential competitors and predators (Pechmann et al. 1989, Semlitsch et al. 1996). Interactions among these community members are poorly documented. Larvae of the Mole Salamander and Eastern Newt were common in a pond that was monitored by Semlitsch et al. (1996), and correlative data suggests that juvenile recruitment is low in years when these predators reach high densities in breeding sites.
Adverse Environmental Impacts
Habitat Loss: Pseudacris ornata has declined in many areas of its range in association with the loss or degradation of habitats. Urbanization has eliminated some populations, and the degradation and loss of seasonal wetlands is a serious issue (Dodd 2013). Burrow and Maerz (2021) noted that summer fires that historically removed hardwoods from the dried beds of seasonal ponds have been suppressed and hardwoods have taken over many of these sites. In their studies, tadpoles generally performed poorly in pools that simulated closed-canopy conditions.

The conversion of natural pine habitats to industrial pine plantations that often use intensive site preparation practices appear to have impacted many populations (Means and Means 2005, Wigley et al. 1999). A recent study by Haggerty et al. (2019) in Florida suggests that the loss of forest ground cover in pine plantations that surround breeding sites is linked to population declines. Burrow et al. (2021) found that the young metamorphs are vulnerable to predation from a native ant (Dorymyrmex smithi) that has proliferated due to historical soil disturbance and altered fire regimes that have decreased wiregrass and other herbaceous ground cover.
Habitat Fragmentation: We have little data on the extent to which populations can tolerate habitat fragmentation, but many populations have declined in urban settings where the landscape is usually highly fragmented.
Status in North Carolina
NHP State Rank: S2
Global Rank: G4
Status in North Carolina: E
Environmental Threats: the greatest threats to this species in North Carolina are habitat destruction and degradation associated with urbanization, the destruction of seasonal wetlands, and forest management practices that allow the encroachment of hardwoods into seasonal wetlands.
Status Comments: Populations in North Carolina appear to have declined significantly in recent decades due to the loss or degradation of seasonal wetlands and forest management practices. This species is in need of protection, particularly given that North Carolina populations comprise a genetically distinct clade.
Stewardship: Populations are best maintained by protecting seasonal and semipermanent wetlands that are embedded in Longleaf Pine communities. Prescribed burning may help maintain open-canopy breeding sites by suppressing hardwoods. If burning is not feasible or is ineffective, then mechanical removal and/or chemical treatment of hardwoods in small breeding sites may help to open up the canopy and improve conditions for larval growth and development.