Amphibians of North Carolina
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NC Records

Lithobates kauffeldi - Mid-Atlantic Coast Leopard Frog

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Taxonomy
Class: Amphibia Order: Anura Family: Ranidae Synonym: Rana kauffeldi Other Common Name(s): Atlantic Coast Leopard Frog
Taxonomic Comments: Frost et al. (2006) placed species in North American that were formerly in the very large genus Rana into a separate genus, Lithobates, to distinguish them from a large and predominantly Eurasian genus Rana (sensu stricto). There have been numerous arguments put forth for well over a decade about whether these species should be placed back into Rana or retained as Lithobates, with some supporting placing Lithobates as a subgroup within Rana and others supporting the recognition of both genera. There has been no clear resolution of the issue, and both Lithobates and Rana continue to be widely used in recent published literature on North American species. Here, we follow the recommendations of the Society for the Study of Amphibians and Reptiles' Standard English Names Committee and use Lithobates for North American representatives of this group.
Species Comments: This species was described in 2014 and most aspects of its life history are poorly documented. It reaches it southernmost range limit in North Carolina and its life history and distribution within the state is in need of study.
Identification
Description: Adults of Lithobates kauffeldi are very similar to the Southern Leopard Frog (L. sphenocephalus). This newly described species is a medium-sized frog with a variable dorsal ground color that can be shades of dark olive-green, brown, bronze, gray or light green. A conspicuous white or yellow dorsolateral fold in present on each side that extends from behind the eye to near the attachment of the rear leg, and a rather dull white spot is usually present in the center of the tympanum. A series of large, rounded to oval, brown spots are present on the back, along the sides, and on the back legs. The hind legs are long with webbed toes, and there is a light line on the upper jaw. The belly, chest and undersides of the legs are white. The hidden portion of the back of the hind leg is predominantly dark with small, unconnected dots of whitish to yellowish-white pigment.

Lithobates kauffeldi can be difficult to distinguish from L. sphenocephalus and is most reliably separated using the advertisement calls. Schlesinger et al. (2018) conducted a comprehensive survey and morphological comparison of these two species in areas of geographic overlap and found that there is no single character that will reliably distinguish between the two. However, they were successful about 90% of the time in identifying L. kauffeldi (verified with genetic markers) using a combination of traits.

The reticulated pattern on the hidden portion of the back legs is most helpful. According to Schlesinger et al. (2018) nearly all L. kauffeldi are predominantly dark with small, unconnected dots of light pigment, while most L. sphenocephalus are predominantly light with large, connected blotches of dark pigment. Unfortunately, a small percentage of specimens of L. sphenocephalus can have the pattern that is typical of L. kauffeldi. In addition to the leg patterning, the overall dorsal coloration of L. kauffeldi is typically duller than that of L. sphenocephalus, and specimens are less likely to have sharp tympanum spots (58% versus 91% of L. sphenocephalus specimens had sharp spots). The snout of L. kauffeldi is also more frequently viewed as being “blunt” (62% of specimens) relative to L. sphenocephalus (13% of specimens). The most important field characters for distinguishing between species are the reticulum color, the reticulum pattern, and the snout shape. The authors noted that the advertisement call as described by Feinberg et al. (2014) is the only truly diagnostic feature that can be used in the field. Identification is further confounded by the fact that over 10% of the specimens that were genetically analyzed were hybrids with admixtures of genes from both species.

The tadpoles have not been described and it is uncertain if they are morphologically distinguishable from those of L. sphenocephalus.
Vocalizations: The call is a single-noted, unpulsed ‘chuck’ that is distinct from the pulsed ‘ak-ak-ak’ of L. sphenocephalus. The ‘chuck’ call is typically emitted in evenly spaced, repeated series that can include up to 27 ‘chucks’ over 22 seconds, and is occasionally accompanied by secondary ‘groans’ (Feinberg et al. 2014). Average values for the ‘chuck’ call that were reported by Feinberg et al. (2014) for males that were recorded in the field at 10-11°C include a call length of 60.6 ms, a call rate of 1.10 calls/s, and a dominant frequency of 1296 Hz. The authors noted that the quivering ‘quack’ of L. sylvaticus is superficially similar but consists of discrete bouts of 2–4 rapidly pulsed notes that are never accompanied by secondary ‘groans’ as occasionally emitted by L. kauffeldi. These species typically sort out by habitat, with L. sylvaticus using smaller forested pools versus larger, open-canopied wetlands for L. kauffeldi.
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Observation Methods: Observations are best made by searching for calling males during warm, rainy periods in February and March.
AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: Lithobates kauffeldi has been found in Connecticut, New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, and North Carolina (Schlesinger et al. 2018). This species is restricted to the northeastern portion of the Coastal Plain in North Carolina. Schlesinger et al. (2018) reported that 89% percent of known populations were within 20 km of coastal waters.
Distribution Reference: Schlesinger et al. (2018)
County Map: Clicking on a county returns the records for the species in that county.
GBIF Global Distribution
Key Habitat Requirements
Habitat: Lithobates kauffeldi is mostly restricted to large coastal and riparian wetlands. Feinberg et al. (2014) described this species as inhabiting mesic lowland habitats that primarily include coastal freshwater wetlands, tidally influenced backwaters, and interior riparian valley floodplains. It is typically associated with large wetland complexes composed of open-canopied marshes, wet meadows, and slow-flowing systems with ample open upland and early-successional habitats. Aquatic conditions are usually clear, shallow, and sometimes ephemeral, with emergent shrubs or herbaceous plants such as cattails or Common Reed (Phragmites australis).

(Schlesinger et al. 2018) conducted a broader geographic survey of this species and noted that it is commonly found in riparian cypress-gum swamps in the southern portion of the range, including North Carolina. It also occupies large freshwater impoundments, tidal guts, and tidal freshwater marshes that may be subject to salinity intrusions. In the northern portion of the range it can be found outside of the Coastal Plain in the Piedmont, New England, and Valley and Ridge physiographic provinces where there is greater topographic relief and a greater diversity of habitat types.
Life History and Autecology
Breeding and Courtship: Calling, and presumably breeding, occurs primarily from mid-winter through mid-spring depending on the latitude (Schlesinger et al. 2018). Males have been heard as early as early February in North Carolina, late-February in Virginia, mid-March in Delaware, and early to mid-March in New York (Feinberg et al. 2014, Schlesinger et al. 2018). Calling can occur as late as late April in New Jersey, and may occur very sporadically into late April and May in New York. There is one record for calling males for mid-June in New Jersey’s Meadowlands.

The adults often move to the breeding sites on rainy nights. Feinberg et al. (2014) noted that chorusing in New York occurs most consistently at night when air temperatures range from 10–18C, although sustained chorusing during both the day and night is common early in the season and through the initial 2–3 weeks of peak breeding. This is particularly evident on relatively warm days. After the peak in breeding, chorusing tends to be more episodic and nocturnal, with calling bouts triggered by rain.

Information on the breeding biology is scant, but Feinberg et al. (2014) reported that calling males congregate in small groups that typically include five or more frogs. They can be separated by as little as 30 cm between individuals. The males were observed calling while floating in shallow water with emergent vegetation. The calls do not carry far, and the authors surmised that the formation of dense aggregations may help broadcast sounds where there is often acoustic interference from other anurans such as Spring Peepers that simultaneously call at the breeding sites.
Reproductive Mode: Feinberg et al. (2014) reported that the egg masses are often clustered in groups or deposited near one another.
Aquatic Life History: Aspects of the larval life history are unreported.
Terrestrial Life History: Very little is known about the terrestrial stages of the life cycle.
General Ecology
Population Ecology: We know very little about the population dynamics or ecology of this species. The adults are terrestrial, but the extent to which the juveniles and adults migrate to the surrounding uplands is undocumented. Data on dispersal distances and genetic connectivity are needed, particularly given that many populations occur in highly fragmented urban and suburban settings where major road systems may act as complete barriers to movements.

Adverse Environmental Impacts
Habitat Loss: Most populations of L. kauffeldi are found in highly urbanized and suburbanized landscapes, and its need for large wetlands may make it vulnerable to habitat fragmentation. Schlesinger et al. (2018) reported that populations have disappeared from a large part of its historical range in southern New York and Connecticut where there has been widespread development.
Status in North Carolina
NHP State Rank: S3
Global Rank: G3G4
Status in North Carolina: W3
Environmental Threats: In unprotected areas, habitat fragmentation and the loss or degradation of aquatic and terrestrial habitats may present significant challenges for this species in North Carolina.
Status Comments: Schlesinger et al. (2018) considered populations to be secure in the core of the range (New Jersey; Delaware; Virginia) where there appear to be many apparently large populations in protected wetlands. Populations appear to have declined in other areas such as eastern Pennsylvania, southern Connecticut, and southern New York where this species is now rare. In North Carolina, the status of this species is uncertain and additional field surveys are needed to determine its distribution and abundance.