Amphibians of North Carolina
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NC Records

Pseudacris crucifer - Spring Peeper

Class: Amphibia Order: Anura Family: Hylidae Subfamily: Hylinae
Taxonomic Comments: Herpetologists previously recognized two subspecies of the Spring Peeper that comprised northern (Pseudacris c. crucifer) and southern (P. c. bartramiana) groups, but molecular evidence do not support the recognition of these subspecies (Dodd 2013). This species does show substantial genetic differentiation across it range with six major mtDNA lineages. Cairns et al. (2021) analyzed and summarized information on mitochondrial and nuclear variation, along with geographic variation in calls. The six major mtDNA lineages showed extensive geographic and mitonuclear discordance. There were three nuclear lineages that contained six more structured mtDNA lineages, along with nuclear introgression at some contact zones. Geographic patterns of variation in male advertisement calls were also mostly incongruent with the genetic structure that was observed. The authors believed that this group is best treated as a single species that is in early stages of speciation.
Species Comments:
Description: Adults of the Spring Peeper are small frogs with a light tan to dark brown dorsal ground color and rather inconspicuous toe pads. The ground is overlain with darker patterning that typically consists of an X shape on the back, a V-shaped line that connects the eyes, and a few bands on the legs. A brown stripe extends along each side from the nares through the eyes to the shoulders. On many specimens it continues from the shoulders posteriorly as a broad, diffuse band along the lower sides. The belly and chest are light and normally unmarked, and the undersides of the legs are flesh-colored. Males have a dark vocal pouch that is usually evident year-round, but that is more prominent during the breeding season. In general, the juveniles tend to be lighter colored and have less conspicuous patterning.

The adults vary from 18-37 mm SUL, and the males average 5-14% smaller than the females in local populations (Dodd 2013). Some representative values provided by Dodd (2013) include 23–30 mm SUL (mean = 28 mm) for males and 29–34 mm SUL (mean 31 mm) for females from Florida, 18–30 mm (mean = 24 mm) for males and 23–33 mm SUL (mean 28 mm) for females from New York, and 21–30 mm SUL (mean 25 mm) for males and 23–35 mm SUL (mean = 28 mm) for specimens from Connecticut.

The tadpoles have squared snouts, widely spaced eyes, and deep bodies that are medium brown with scattered golden flecks (Dodd 2013, Jensen 2008). The tail is medium-sized and the musculature is mottled. The fins can be either clear or have scattered blotches that are generally absent from near the fin base where it attaches to the tail musculature.
Vocalizations: The advertising call is a familiar sound to most naturalists in eastern North America and consists of a high-pitched whistle or peep, with each peep ascending in pitch and lasting about one-fifth of a second. The calls are made in a long, repetitive sequence, “peep"- “peep"- “peep" - “peep"- “peep" and are typically repeated about every half second to three-quarters of a second depending on the temperature (Dodd 2013).

The Spring Peeper also makes a trilling call that is used to induce calling by duet or triplet members, and another to warn males that are trespassing on a calling male's territory. Males may also modify their advertisement call when a female approaches. In addition to breeding calls, solitary peepers are sometimes heard calling in single notes from the tree canopy during the autumn (Dodd 2013).
Technical Reference: Dodd (2013)
Online Photos:    Google   iNaturalist
Observation Methods: The calling adults are a familiar sound during the spring warm-up and provide an easy way to document local populations. Adults can frequently be found on rainy nights moving to and from the breeding sites.

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AmphibiaWeb Account
Distribution in North Carolina
Distribution Comments: The Spring Peeper occurs across a large swath of eastern North America. In Canada, it occurs from the Canadian Maritime provinces westward to southeastern Manitoba. The range includes most of the eastern US from the northeastern states westward to eastern Minnesota and southward to eastern Texas, the Gulf Coast states, Georgia, and central Florida.

This species occurs statewide in North Carolina from coastal areas to mostly lower elevation sites in the mountains. Due to its affinity for hardwoods, it is less common in the Coastal Plain relative to the Piedmont and Blue Ridge. It also appears to be absent from the barrier islands.
Distribution Reference: Beane et al. (2010), 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 juveniles and adults live in forested habitats that have breeding sites that are either in the forests or in open areas close to forests. Given their broad geographic range, the adults use terrestrial habitats that range from conifer-dominated forests in the far north to mesic hammocks in Florida. In the eastern US they commonly occur in mesophytic hardwood forests, mixed pine-hardwood forests, and upland and bottomland hardwoods. Dodd (2013) noted that they can also be found in xeric hammocks, Great Lakes pine barrens, and tamarack forests. Their western range limit in the US is strongly tied to the western limit of the Eastern Deciduous Forest.

The adults use a wide range of breeding sites. Seasonal or semipermanent ponds that lack fish are important habitats throughout the range, but permanent sites such as beaver ponds, farm ponds and lakes are also used. Babbitt et al. (2003) found that seasonal or semipermanent habitats that hold water for at least 4 months are most preferred. Sites that are sunny or partially shaded are preferred over closed-canopy sites, and the larvae generally perform better in these habitats (Skelly 2001, Skelly et al. 2002, Williams et al. 2008). The habitats can range from small mud puddles to lakes and reservoirs, and from habitats with little vegetative cover to others with extensive surface vegetation (Dodd 2013).

In North Carolina, populations occur in a variety of forested habitats, including bottomland forests, mesic to somewhat drier hardwood or mixed pine-hardwood forests, and coastal swamplands. We have a few records from sites in pine savannas, but it is uncertain if hardwoods were nearby. Representative breeding habitats include vernal ponds, floodplain pools, beaver ponds, swamps, bogs, Carolina Bays, marshes, roadside ditches, borrow pits, farm ponds, and the vegetated, shallow areas of lakes.
Environmental and Physiological Tolerances: The eggs and larvae are sensitive to highly acidic waters, with hatching success decreasing at a pH of 4.3 or lower and larvae showing decreased activity when the pH is < 4.5 (Dodd 2013, Karns 1992, Freda 1986, Freda and Taylor 1992). Populations generally use ponds with a pH of 5 or higher (Dale et al. 1985, Karns 1992, Owen 1996).
Biotic Relationships: The larvae are palatable to aquatic predators such as fishes, newts, Ambystoma larvae, and aquatic insects (Kats et al. 1988, Kurzava and Morin 1998, Lawler 1989, Skelly 1992). Their primary defense appears to be to rely on crypsis and to remain relatively immobile, particularly when in the presence of predators (Lawler 1989, Richardson 2001, Skelly 1992). Very early breeding likely helps to reduce predation from aquatic predators that colonize pools later in the year.

The juveniles and adults are palatable and are preyed upon by numerous species. Dodd (2013) listed some of the known predators that include trout, aquatic snakes, Barred Owls, skunks, ground beetles, giant water bugs, and dytiscid diving beetles. The latter killed individuals that were calling at a breeding site (Hinshaw and Sullivan 1990). Spiders are also known predators (Nyffeler and Altig 2020). The juveniles and adults are excellent jumpers and probably use fleeing as one of their primary defenses against terrestrial predators. They blend in well with leaf litter or bark and can change colors to better match their backgrounds (Kats and Van Dragt 1986). When approached by a predator they may also remaining motionless, crouch, or inflate their bodies (Marchisin and Anderson 1978).
See also Habitat Account for General Forests and Shrublands
Life History and Autecology
Breeding and Courtship: The calling and breeding seasons vary markedly depending on latitude and elevation. In Florida calling begins in late October and extends into April (Krysko et al. 2019), while in Canada the males typically begin calling in April and continue through June or July. Dodd (2013) has detailed information for numerous localities throughout the range. Males frequently begin calling in November or December in the Deep South during bouts of warm weather, but actual mating and egg laying typically happens 1-3 weeks after the first males begin to call.

Calling in North Carolina can sometimes be heard in November and December during warm weather. However, the formation of large choruses and associated breeding normally does not occur until January or February in areas outside of the mountains. It may continue through April (Murphy 1963, Alexander 1966, Gaul and Mitchell 2007). Although vigorous chorusing has been documented as early as January in the mountains, populations generally begin calling in earnest in late February or March and may continue into early July at higher elevations (Dodd 2013).

The adults migrate to and from the breeding sites at night during rainy weather (Pechmann and Semlitsch 1986, Todd and Winne 2006). Movements to a local breeding site often occur over the course of several weeks and the adults do not engage in explosive breeding (Dodd 2013). In North Carolina individuals may linger at the breeding sites for several weeks after seasonal chorusing ends, then move back to wooded retreats (Murphy 1963).

After arriving at a breeding site the males set up calling stations in or near the water. Individuals may call sporadically throughout the day, but most chorusing occurs from late afternoon through the first several hours after dark (Dodd 2013, Owen 1996, Steelman and Dorcas 2010). Individuals may call from the lower branches of shrubs or other vegetation around a pond margin, or from within the pond proper while sitting in shallow water near the pond edge, or resting on or beneath grass mats, sedge hummocks, moss clumps at the base of trees, or emergent plants. Individuals rarely perch more than 1-2 meters above the water when calling from shrubs or other vertical vegetation. Dodd (2013) noted that the males are capable of calling in very cold weather when temperatures are just a few degrees above freezing, but the optimal temperatures for calling are 10–20°C (Steelman and Dorcas 2010).

Males normally outnumber females at the breeding sites and complete for the limited number of females. For example, at a North Carolina site, Murphy (1963) found a 1.43:1 sex ratio one year, and 1.2:1 males per female the next year, while Oplinger (1966) found a 9.2:1 ratio in New York. The dominant males establish small calling territories and often call in close proximity to one another. Studies in Missouri (Gerhardt et al. 1989), Maryland (Fellers 1979a) and elsewhere show that they commonly space 20-140 cm or more apart (Dodd 2013).

Communication among rivals is facilitated by both altering characteristics of the advertisement call and using warning calls (Dodd 3013, Rosen and Lemon 1974, Schwartz 1989). Individuals do not increase their advertisement call rates when another male in close, but do increase the length of the call (Fellers 1979a, Sullivan and Hinshaw 1990). Rival males also communicate by producing trills, which are warning or aggressive calls that are often graded depending on the level of threat (Schwartz 1989). Interactions between rivals may eventually escalate into aggressive encounters. In addition to calling males, noncalling satellite males sometimes occur in close proximity to the calling males and are occasionally successful in amplexing females that are moving towards calling males (Forester and Lykens 1986). Gatz (1981b) found that males from amplexed pairs were slightly larger than single males, which suggests that females may show a slight preference for larger males.

Neighboring frogs frequently call in duets or triplets, with the calls mostly staggered to avoid overlap (Rosen and Lemon 1974). Calling males often alter their calls when a female approaches. Females appear to use call characteristics to discriminate between males (Lykens and Forester 1987). Each female will make her way to the male of her choosing, then nudge him to initiate axillary amplexus (Dodd 2013). Egg laying and fertilization normally begins several hours later.
Reproductive Mode: Females lay their eggs singly or occasionally in small clusters of a few eggs. They attach them to submerged vegetation, twigs, leaves, or other substrates in the pond. As the female releases an egg she arches her back to bring her cloaca in close contact to the male's cloaca to facilitate fertilization. The pair will typically swim about for short distances and scatter small groups of eggs at different sites in the pond (Wright 1914).

The freshly laid eggs are brownish to black above and white or cream-colored below and are surrounded by a single jelly envelope. Gosner and Rossman (1960) reported a mean egg diameter of 1.1 mm for eggs from two Florida females, with the jelly envelope averaging 2.6 mm. Wright (1914) reported a mean egg diameter of 1.0 mm (range = 0.9-1.1 mm) for New York specimens, with the envelopes varying from 1.4-2.0 mm in diameter (mean = 1.7 mm). Eggs that are maintained in the lab at room temperature hatch in 4-6 days, but an incubation period of 5-15 days or even longer is more typical in natural breeding sites (Dodd 2013, Wright 1914).

Data of clutch size is rather scarce. The clutch sizes of 72 Virginia females that laid eggs in captivity varied from 242–1,648 and averaged 889 eggs (Mitchell and Pague 2014). Clutch size in this sample showed a weak but insignificant tendency to increase with female SUL (N = 24).
Aquatic Life History: The hatchlings are around 4-4.5 mm TL and the mature larvae metamorphose when around 33-39 mm TL (Dodd 2013, Harper 1939a, Wright and Wright 1949, Gosner and Black 1957a, Gosner and Rossman 1960). The larvae feed throughout the day and are inactive feeders that scrape the substrate, often nibbling with little movement of the body or tail. They do not actively swim through the water while feeding or form feeding aggregates as seen in some seasonal pond breeders. The food items include detritus and diatoms, filamentous, colonial, and unicellular green algae, blue-green algae, protozoans, invertebrates, and the eggs of crustaceans (Dodd 2013, Munz 1920, Quammen and Durtsche 2003). The rather low-keyed lifestyle of the tadpoles results in slower growth rates and longer larval periods than some of the active feeders like Scaphiopus or Anaxyrus. The larvae are readily preyed upon by odonates and will reduce their activity levels even further when with odonates (Smith and Van Buskirk 1995).

Larval densities in North Carolina vary from 12 to 464 larvae per cubic meter of pond water (Morin 1983), and larvae may compete for food resources when at high densities. Growth rates, length of the larval period, and size at metamorphosis are influenced by ambient pond conditions such as water temperatures, food quality and quantity (Hensley 1993), the densities of conspecific and heterospecific competitors, and the presence of predators. Crowding slows growth and development and reduces the average size at metamorphosis (Crump 1981a). The presence of odonate predators can reduce activity levels and also reduce growth rates (Van Buskirk 2000).

Length of the larval period is variable and appears to be shorter on average in southern populations where the breeding sites are warmer. Dodd (2013) noted that the larval period typically lasts 45-65 days, but may last up to three months in northern populations such as those in Canada and New York (MacCulloch 2002, Wright 1914). The metamorphs typically vary from around 9-15 mm SUL. Representative values that were provided by Dodd (2013) include 9–11 mm in Florida, 10–17 mm (mean = 13.5 mm) in South Carolina, 9–13 mm in North Carolina (Alexander 1966), 10–11 mm in Maryland, and 9–14 mm (mean = 11 mm) in New York.
Terrestrial Life History: The young metamorphs may remain in the vicinity of breeding sites for a few weeks before dispersing into the surrounding forests. In Missouri, Hocking et al. (2008) found that all of the metamorphs had dispersed into surrounding oak-hickory forest by mid-June to mid-July. The juveniles and adults live secretive lives and are only occasionally seen outside of the breeding season. Their enlarged toe pads allow them to climb, but they appear to spend much of their time either in the leaf litter or in low-growing vegetation. Delzell (1958) found that adults in Michigan moved as far as 550 m from the nearest breeding site. Most established small home ranges in the woods and remained near piles of bark, logs, stumps, or vegetation. Some left their home ranges in late summer and moved into ecotones and open fields, but most overwintered in the woods.

The juveniles and adults take a broad range of prey and appear to be gape-limited, generalist predators. The young juveniles consume small prey such as ants, larval lepidopterans, spiders, beetles, springtails and mites. The adults continue to take small invertebrates, but add larger prey to the diet as well. Dodd (2013) noted that the adults consume numerous taxa of invertebrates, including aphids, ants, mosquitoes, fungus gnats, crane flies, larval lepidopterans, beetles, spiders, ticks, mites, phalangids, springtails and terrestrial gastropods.

Many juveniles appear to reach sexual maturity within a year after metamorphosing and breed for the first time the following spring (e.g., Delzell 1958). Others, particularly the females, may require an additional year before they first breed (Dodd 2013, Lykens and Forester 1987). Alexander (1966) estimated that between 36–67% of females in a Piedmont population in North Carolina do not breed until their second year of life. Lykens and Forester (1987) conducted skeletochronology studies of adults from three pond populations in Maryland and found that individuals do not survive beyond four years of age. Almost all do not breed until they are two years old (entering their third spring), and many only breed once in their lifetimes.
General Ecology
Population Ecology: Local populations of the Spring Peeper can vary from a few dozen individuals at small breeding sites to a thousand or more at larger sites. We have very little data on dispersal distances or the extent to which local populations are interconnected.
Community Ecology: This species tends to use ponds that have long hydroperiods and that are shared by numerous predators and competitors. The larvae appear to primarily rely of being cryptic and relatively immobile to reduce predation risk. However, reduced activity may compromise feeding efficiency and cause slower growth rates, which in turn may compromise the ability of larvae to compete with other anurans. Morin and Johnson (1988), for example, found that the Wood Frog tadpoles that are more active and feed in aggregates were superior competitors in artificial ponds. In a more complex experiment that used several native anurans, survivorship in the absence of predators was near zero and active feeders like Scaphiopus holbrooki were competitively superior (Morin 1983). When adults of the Eastern Newt was added as a predator, P. crucifer performed better than any species. This reflects the fact that newts had a greater adverse effect on fast-swimming, active feeders than on P. crucifer tadpoles that tended to remain immobile.

Another study that addressed seasonal phenology showed that the relative time of breeding can influence competitive outcomes. Using artificial ponds, Lawler and Morin (1993) found that P. crucifer performed well if tadpoles were added before those of Fowler's Toad. When the reverse occurred, P. crucifer tadpoles had longer larval periods, slower growth, and were smaller at metamorphosis - all signals of interspecific competition. Pseudacris had little effect on Anaxyrus regardless of the experimental treatments.

Despite the potential adverse effects of competitors and predators on the tadpoles, this species is often one of the most common anuran species at shared breeding sites, with the adults often times engaging in deafening choruses. A fundamental challenge of many of the experiments conducted in laboratory aquaria and outdoor pools is to better understand to what extent the results apply to natural breeding sites.

Adverse Environmental Impacts
Effects of Pollution: Pseudacris crucifer is highly sensitive to heavy metals and its presence is negatively correlated with the atmospheric deposition of cadmium, nickel, and other correlated metals (Dodd 2013).
Status in North Carolina
NHP State Rank: S5
Global Rank: G5
Environmental Threats: Populations in North Carolina are strongly affiliated with deciduous or mixed pine-deciduous forests. Studies elsewhere indicate that this species is often absent or underrepresented in cut-over lands, urban areas, and agricultural land where forested areas are not in close proximity (Anderson and Arruda 2006, Dodd 2013, Knutson et al. 2004, McLeod 1995, McLeod and Gates 1998).
Status Comments: Pseudacris crucifer is common and populations appear to be stable in most portions of the species range. Dodd (2013) noted that populations appear to be declining in some northeastern states, but are increasing in some areas. Populations in North Carolina show no evidence of widespread declines.
Stewardship: Populations are best maintained by having a series of ponds or marshy habitats with hydroperiods that last for 6-10 months per year on average. Deciduous forest should be maintained within 50-100 m of the breeding sites, and preferably closer.

Recording Gallery for Pseudacris crucifer - Spring Peeper

2022-03-07. Orange Co. Steve Hall - A few heard singing around the edge of the slough (contains fish), with Pickerel and Leopard Frogs also chorusing, along with American Toads. Between 2100 and 2200 following a heavy downpour. ~64 F.

2022-03-18. Richmond Co. Jim Petranka and Becky Elkin - Calling in late afternoon; air temp. ca. 70F

2022-04-13. Madison Co. Jim Petranka and Becky Elkin -

2022-04-13. Madison Co. Jim Petranka and Becky Elkin -

Photo Gallery for Pseudacris crucifer - Spring Peeper

11 photos are shown.

Recorded by: Andrew W. Jones
Polk Co.
Recorded by: Rob Van Epps
Hoke Co.
Recorded by: Rob Van Epps
Hoke Co.
Recorded by: K. Bischof
Transylvania Co.
Recorded by: G. Schneider
Buncombe Co.
Recorded by: Rob Van Epps
Mecklenburg Co.
Recorded by: Owen McConnell
Durham Co.
Recorded by: Steve Hall, Sara Childs, Linda Pearsall, Ann Prince
Orange Co.
Recorded by: Mark Shields
Onslow Co.
Recorded by: Owen McConnell
Durham Co.
Recorded by: Jim Petranka
Buncombe Co.