Lithobates virgatipes

Geographic Range

Carpenter frogs are found in the Atlantic coastal plain of North America, from the Pine Barrens of New Jersey to the Okefenokee Swamp region of southern Georgia and northernmost Florida. Their range extends farther inland in southern North Carolina and in South Carolina.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Carpenter frogs live in a variety of habitats which contain still or slow moving water and an abundance of aquatic vegetation. They can be found in Delmarva bays, sphagnum bogs, flooded cranberry bogs, artificial lakes, and pine barren ponds. They prosper in wetlands with acidity levels exceeding the threshold for other members of the genus Rana . In areas where pig frogs ( Rana grylio ) are present carpenter frogs may be present in lower abundance. In northern Florida carpenter frogs can be found in cypress dome and gum swamps, the only area they are found in that state. It is said that carpenter frogs are found in waterways that are tea or coffee colored, where they can easily be camouflaged. Carpenter frogs are often seen completely out of water but never at a large distance from water. They depend on aquatic vegetation in shallow waters for protection and breeding.

• Habitat Regions
• temperate temperate
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• temporary pools
• coastal coastal

• Wetlands
• marsh marsh
• swamp swamp
• bog bog

• Other Habitat Features
• riparian riparian

Physical Description

Carpenter frogs are medium sized frogs ranging from 4.1 to 6.6 cm (1.6 to 2.6 inches). They have a brown head, body and legs. Male carpenter frogs have a narrower head than females. There are four distinct yellowish or golden brown stripes that run down the back and sides of these frogs. Two of the stripes run closer to the centerline of the body, while the second two are more lateral. Carpenter frogs are unique in that they have no dorsolateral folds and the webbing of their feet does not reach the longest toe. The underside is cream to yellow in color with dark mottling that is present in no particular pattern. Mottling patterns are often black. A light line is present on their upper lip. Carpenter frogs have paired throat pouches which are spherical when inflated.

Carpenter frog tadpoles are large, growing up to 9 cm in length. Like their adult counterparts they are brown, with a white speckled underbody. The tail has dark stripes formed from prominent lines of dark spots which run longitudinally through the musculature. The spots will most often fuse to form dark stripes.

Carpenter frogs can be confused with northern green frogs ( Rana clamitans ), young American bullfrogs ( Rana catesbeiana ), dark southern leopard frogs ( Rana sphenocephala ) and young pig frogs ( Rana grylio ). Northern green frogs and young American bullfrogs lack the yellowish or golden brown stripes present on carpenter frogs. Dark southern leopard frogs have a light spot in the middle of their tympanum, which carpenter frogs lack. Southern leopard frogs lack two of the four stripes present on carpenter frogs. Young pig frogs have pale dorsolateral stripes which sometimes may be unseen at first glance. Their toes are webbed almost to their tips, which is not the case in carpenter frogs.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes shaped differently

Development

Carpenter frog eggs will hatch approximately one week after laying, depending on water temperature. Tadpoles will live in that state for roughly one year, growing up to 9 cm. They spend the winter in breeding ponds. Between August and September of the following year carpenter frog tadpoles will metamorphose into juveniles.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

When breeding season begins male carpenter frogs establish and defend their territories through calls. They select territories in shallow wetlands that consist of both still waters and submerged shrubs. The number of calling sites present in a wetland are directly related to the amount of submerged vegetation present that is suitable for laying eggs.

Through the use of aggressive vocalizations, consisting of three different calls, upright posting displays, and combat practices, male carpenter frogs mark their territory and try to attract the attention of females. Combat practices involve males wrestling for brief periods of time. During the wrestling match the males will interlock their front legs in an amplexus like embrace. This is done by attempting to mount each other. Simultaneously males may make aggressive calls that are growl-like. These activities are used to help draw attention from females.

If females are interested in the male based upon his physical display or calls she will approach the male and sometimes communicate with the male with a chirp like call. This chirp like call is not always noticed in male and female carpenter frog interactions. This particular behavior is more common and unique among Delmarva frog populations. Following male and female interaction, mating may occur.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Carpenter frogs typically mate and lay their eggs between April and July. Female carpenter frogs will deposit a globular mass consisting of up to 600 eggs. The oblong mass is attached to submerged aquatic vegetation within the male’s territory. Egg masses are not attached to vegetation at a depth greater than 30 cm. Each mass ranges from 75 to 100 mm in diameter. Carpenter frog eggs and embryos have the same level of tolerance to acidic water as do adults. Gosner and Black (1957) demonstrated that at a pH of 3.8 or lower resulted in abnormal development. The same results were found when salinity levels were between 0.15 to 0.30 grams per 100 cc.

Females may lay several egg masses throughout a breeding season. Given (1987) demonstrated that males called on 95% of the nights. As a result, he concluded that males almost continuously call and engage in mating activities throughout the breeding season. Findings also show that calling efforts by smaller males are lower than those of larger males. Smaller males tend to grow more during breeding season.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • external external
• oviparous oviparous

Specific information pertaining to parental care in carpenter frogs has not been documented. However, most species in the genus Rana invest little in parental care after having laid and fertilized eggs.

• Parental Investment
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female

Lifespan/Longevity

The longest lifespan documented in captivity was 6 years and 2 months. Wild lifespans carpenter frogs have not been documented.

Behavior

Carpenter frogs are described as a secretive species. They are often difficult to see or capture due to their natural camouflage and shy behavior. When frightened they quickly dart away underwater and raise their head after a very brief period to reevaluate the situation and surroundings. They will usually only have their head exposed during these times.

Carpenter frogs are nocturnal animals. They aggregate in large numbers in suitable habitat.

• Key Behaviors
• saltatorial saltatorial
• natatorial natatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial

Home Range

Carpenter frogs are found near wetlands throughout the year. While they are most often seen completely out of water they are never far from a water source.

Communication and Perception

Carpenter frogs were assigned their common name based upon their hammering call. When carpenter frogs are calling in a chorus it is often described as sounding like a crew of workmen hammering. When an individual carpenter frog is calling it is described as sounding like two carpenters hammering nails one fraction of a second after each other. While most people have said that the call is “pu-tunk, pu-tunk, pu-tunk.” Males are capable of emitting the call ten times in succession.

Given (1987) demonstrated that carpenter frogs have five other less identifiable calls. Three of which are for aggressive purposes, one release call used when males accidentally grab each other, and one chirp call used by females for courtship. Given (1999) also found that when males call in aggressive situations, they will follow those calls with an advertisement call for attracting females. When they appear to still in be in aggressive situations following the initial call they will adjust their advertisement call to a more aggressive sounding call while still including the necessary components to attract females.

Carpenter frogs also communicate with each other through their breeding practices. Males communicate with the females by displaying their upright posture and combating with other males.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• choruses choruses

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Carpenter frogs forage on the ground and in vegetation for small insects and other small invertebrates.

• Primary Diet
• carnivore carnivore
  • insectivore insectivore
  • eats non-insect arthropods

• Animal Foods
• insects
• terrestrial non-insect arthropods
• mollusks

Predation

While there is little published information pertaining to natural predators of carpenter frogs, some research suggests that water snakes ( Nerodia ) eat carpenter frogs. Zampella and Bunnell (2000) suggest that the presence of American bullfrogs ( Rana catesbeiana ) negatively affects carpenter frog populations. When pig frogs ( Rana grylio ) are present there has also been a noticeable absence or decline in carpenter frog populations. Carpenter frogs are well camouflaged in their natural habitats.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Carpenter frogs co-occur with green frogs ( Rana clamitans ), southern leopard frogs ( Rana sphenocephala ), and Pine Barren treefrogs ( Hyla andersonii ).

Economic Importance for Humans: Positive

Like most frogs, carpenter frogs consume insects that may be considered a nuisance.

• Positive Impacts
• controls pest population

Economic Importance for Humans: Negative

There are no known adverse effects of carpenter frogs on humans.

Conservation Status

According to the 2006 ICUN Redlist, carpenter frogs are of Least Concern. Conservation status varies locally in the United States. In New Jersey, Delaware, and some areas of Virginia they are protected, while in Maryland and other areas of Virginia they are listed as a species of special concern.

Knowing that carpenter frogs thrive in acidic waters it is thought that the neutralization of wetland areas in the Delmarva region may be the cause of their decline in that region. As wetlands become less acidic a larger variety of frogs can inhabit the area including more aggressive species such as northern green frogs ( Rana clamitans ). Historically populations of carpenter frogs have been found in Kent and Sussex County in Delaware, and Queen Anne’s, Talbot, Caroline, Dorchester, Wicomico, and Worcester counties in Maryland. In the 1990s the carpenter frog population in Talbot County was found to be severely decreased as a possible result of habitat degradation.

Areas farther south like Georgia the Carpenter Frog is considered common. However it does have a limited range. Considering that the Carpenter Frog requires wetland areas with large amounts of submerged vegetation for breeding, human disturbances to such environments have and will continue to impact the species.

Additional Links

AmphibiaWeb

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Danielle Morrow (author), Environmental Concern, Inc., Sarah Toman (editor, instructor), Environmental Concern, Inc..

References

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Behler, J., W. King. 1979. National Audubon Society Field Guide to North American Reptiles and Amphibians . Random House Inc.

Conana, R. 1975. The Peterson Field Guide Series: A Field Guide to Reptiles and Amphibians of Eastern and Central North America . Boston: Houghton Mifflin Company.

Given, M. 1999. Distribution records of Rana virgatipes and associated anuran species along Maryland's Eastern Shore. Herpetological Review , 30: 144-146.

Given, M. 1988. Growth rate and the cost of calling activity in male carpenter frogs, Rana virgatipes. Behavioral Ecology and Sociobiology , 22: 153-160.

Given, M. 1987. and acoustic interactions of the carpenter frog, Rana virgatipes. Herpetologica , 43: 467–481.

Gosner, K., I. Black. 1957. The effects of acidity on the development and hatching of New Jersey frogs. Ecology , 38: 256–262.

Hammerson, G. 2006. "NatureServe Explorer" (On-line). Accessed March 20, 2007 at http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Rana+vir gatipes .

Hammerson, G. 2004. "The IUCN Red List of Threatened Species" (On-line). Accessed March 20, 2007 at http://www.iucnredlist.org/search/details.php/58747/summ .

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White, J., A. White. 2002. Amphibians and Reptiles of Delmarva . Tidewater Publishers with Delaware Nature Society.

Zampella, R., J. Bunnell. 2000. The distribution of anurans in two river systems of a Coastal Plain watershed. Journal of Herpetology , 34: 210–221.

USGS Patuxent Wildlife Center. An Introduction to Mid-Atlantic Seasonal Pools. 2005.

Florida Fish and Wildlife Conservation Commission. Conservation Plans for Biotic Regions in Florida Containing Multiple Rare or Declining Wildlife Taxa. 2003.