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Pseudacris streckeriStrecker's Chorus Frog

By Blake Hintz and Taryn Yezek

Geographic Range

Pseduacris streckeri, also known as Strecker's chorus frog, is found in portions of the United States west of the Rocky Mountains, which acts as a geographic barrier. The range extends from southern Kansas to southern Texas. Isolated populations exist in central and southern Illinois, southeastern Missouri, and small parts of western Arkansas. Although questionable, it also may occur in northern Mexico. Data from Mexico, however, remains unreliable. There are no introduced populations. (Elliot, et al., 2009; Hammerson, 2004; Packard, et al., 1998)

Habitat

In comparison to other chorus frogs (Pseudacris), Strecker's chorus frogs are one of the most terrestrial species. They live in a variety of habit types, including moist woods, sand prairies, streams, swamps, and ponds. Strecker's chorus frogs also are know to inhabit temperate grasslands, wetlands, canals, and drainage channels. Most of the time, Strecker's chorus frogs remain burrowed underground. This is possible because they can tolerate a high loss of body water. When not feeding or breeding, chorus frogs burrow approximately six inches (15 cm) into the soil using their front limbs. Larvae and eggs require aquatic habitats and are typically found in small bodies of water such as small ponds, ditches, and flooded fields.

Recently populations of Strecker's chorus frog have been decreasing due to the destruction of breeding habitats. Primary causes include the expansion of agriculture and housing developments in southeast Missouri. (Gray and Stegall, 1986; Hammerson, 2004; Ralin and Rogers, 1972)

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams
  • temporary pools
  • Range elevation
    600 to 2000 m
    1968.50 to 6561.68 ft
  • Average elevation
    1300-1700 m
    ft
  • Range depth
    .01 to .80 m
    0.03 to 2.62 ft
  • Average depth
    .08 m
    0.26 ft

Physical Description

Frogs in the genus Pseudacris are known for their calls, giving them the common name "chorus frogs". Strecker's chorus frogs are stockier than other members of the genus. Strecker's chorus frogs reach a maximum size of 5 cm. Females range from 32 to 46 mm long, while males range from 25 to 41 mm. The subspecies P. illinoensis tends to be slightly smaller, with a maximum length of 3.7 cm. (Blair and Littlejohn, 1960; Brown, 1978; Brown, et al., 1972; Conant and Collins, 1998; Elliot, et al., 2009; Gray and Stegall, 1986; Gridi-Papp and Gridi-Papp, 2005; Handy, 2011; Hazen, 1949; Long, 1999; Packard, et al., 1998; Ralin and Rogers, 1972; Trauth, et al., 2006a; Tucker, 1995)

Dorsal coloration of P. streckeri is brown, gray, olive, or green, with contrasting black spots. Spots may appear grey to brownor green. Dark, sometimes black, splotchy stripes run down the back parallel to the spine. The epidermis is rough in texture, more similar to toads than frogs. These frogs also have a distingushing dark stripe though the eye, and a dark spot or bar beneath the eye. Strecker's chorus frogs differ from other chorus frogs because they lack a continuous thin light line on the upper lip. During the breeding seasons the species displays sexual dimorphism, as the throat coloration in males becomes darker. Pseudacris streckeri begins development as tadpoles. They follow the same development patterns as all frogs. Within two months after tadpoles begin to develop into frogs, the distinct markings of the Strecker's chorus frog starts to appear. (Blair and Littlejohn, 1960; Brown, 1978; Brown, et al., 1972; Conant and Collins, 1998; Elliot, et al., 2009; Gray and Stegall, 1986; Gridi-Papp and Gridi-Papp, 2005; Handy, 2011; Hazen, 1949; Long, 1999; Packard, et al., 1998; Ralin and Rogers, 1972; Trauth, et al., 2006a; Tucker, 1995)

There are a number of closely related species of chorus frogs that are similar in appearance to Strecker's chorus frogs. These include upland chorus frogs (Pseudacris feriarum) and western chorus frogs (Pseudacris triseriata). Compared to western chorus frogs, Strecker's chrous frogs have significantly thicker and larger forelimbs and fingers that lack terminal adhesive disks. This is unusual, as that most species of frogs have thin fingers with terminal adhesive disks. Other unique distinguishing features include a compact body form, dark marks placed high on the cheeks, and a V pattern between the eyes. Strecker's chrous frogs also may be confused with northern cricket frogs (Acris crepitans), a closely related species, but the body of Strecker's chorus frogs is stockier. (Blair and Littlejohn, 1960; Brown, 1978; Brown, et al., 1972; Conant and Collins, 1998; Elliot, et al., 2009; Handy, 2011; Hazen, 1949; Long, 1999; Packard, et al., 1998; Ralin and Rogers, 1972; Trauth, et al., 2006a; Tucker, 1995)

  • Sexual Dimorphism
  • female larger
  • sexes colored or patterned differently
  • Average mass
    3 to 4 g
    oz
  • Range length
    1.9 to 3.8 cm
    0.75 to 1.50 in
  • Average length
    2.5 cm
    0.98 in

Development

After eggs are laid, embryos develop and larva hatch within five days. Larvae then follow the Gosner developmental stages which are similar for all frog species. Around 60 days of age, tadpoles metamorphosize into adult forms. Early adult color patterns will continue to develop. After metamorphosis, growth rates can exceed one millimeter a day, until full size is reached in 60 to 75 days. (Dorcas and Gibbons, 2008; Gray and Stegall, 1986; Long, 1999; Tucker, 1995)

Reproduction

Mating occurs in winter months, usually starting in November and continuing until March. Variations in breeding season are dependent on the amount of rainfall that occurs in those months. Temperature also affects when Strecker's chorus frogs come above ground to breed. Most of the year, Strecker's chorus frogs remain underground. They generally emerge only to mate. Mating calls, high-pitched peep calls, are the primary way that these frogs call females for reproduction. If temperatures fall below 4.5 degrees Celsius (40 degrees Fahrenheit), mating calls tend to cease. (Blair and Littlejohn, 1960; Brown, 1978; Gray and Stegall, 1986; Loftus-Hills, 1973; Long, 1999; Michaud, 1962)

Like most frogs, P. streckeri is oviparous, meaning that females deposit eggs into the external environment. Males then fertilizes the eggs in the environment. Strecker's chorus frogs lay eggs in small temporary bodies of water, small rivers, or small creeks. These habitats typically have few to no predators and provide sufficient water for plant growth. Eggs are laid in large numbers, up to 600 at one time. Once in the water, they resemble small, jelly-like masses that float on the surface. After about 2 to 5 days, eggs hatch. The tadpoles are small but robust. Tadpoles have black or brown with little mottling on dorsal and are white on their ventral. Tadpoles are around 1.5 inches (3.8 cm) long when they start their transformation into frogs, and most mature in 60 to 75 days. (Blair and Littlejohn, 1960; Brown, 1978; Dorcas and Gibbons, 2008; Gray and Stegall, 1986; Loftus-Hills, 1973; Long, 1999; Michaud, 1962; Walls, 1997)

  • Breeding interval
    Strecker's chorus frogs breed every winter when the weather starts to warm up to around 40 degress Fahrenheit.
  • Breeding season
    Strecker's chorus frogs breed from November to March.
  • Range number of offspring
    250 to 600
  • Range time to hatching
    2 to 5 days
  • Range age at sexual or reproductive maturity (female)
    60 to 75 days
  • Range age at sexual or reproductive maturity (male)
    60 to 75 days

Neither males nor females protect the eggs once they are laid. Rather, females lay a large number of eggs at one time to ensure that at least some offspring will survive to adulthood. Since there is no parental investment, tadpoles must ensure their own survival. Tadpoles are known to be cannibalistic, beginning feeding within 28 days of development. This provides them with the necessary amount to protein to survive. (Walls, 1997)

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

Little is known about the lifespan of P. streckeri. However, there have been some accounts of these frogs living up to 3 years in the wild. Since Strecker's chorus frogs are small, they have numerous predators. This is likely to decrease their average lifespan. As they are not available in the pet trade, captive lifespans are unknown. (Jameson, 1956; Trauth, et al., 2006a; Turner, 1962)

  • Range lifespan
    Status: wild
    0 to 3 years
  • Average lifespan
    Status: wild
    2 years
  • Typical lifespan
    Status: wild
    2 to 3 years
  • Average lifespan
    Status: wild
    1.5 years

Behavior

Strecker’s chorus frogs are rarely seen, due to their reluctance to venture above ground except during the mating season. When they find sandy soil, they burrow down, staying below the frost line in winter. Unlike most burrowing frog species, Strecker’s chorus frogs dig with their front feet, rather than hind feet. While they dig, they eat any insect or worm they encounter. This is an example of their opportunistic nature.

During the tadpole stage, Strecker’s chorus frogs find safety among aquatic plants, coming out only to forage for algae and other food sources. If food is scarce tadpoles, may become cannibalistic. It is proposed that cannibalistic morphs may even exist. As an adult, these frogs prefer woodland and field ecotones. During the breeding season, these habitats ring with the songs of male chorus frogs, as they work to attract potential mates. (Blair and Littlejohn, 1960; Brown, 1978; Brown, 1988; Packard, et al., 1998; Trauth, et al., 2006a)

  • Range territory size
    150 to 500 cm^2
  • Average territory size
    300 cm^2

Communication and Perception

The most common form of communication in Strecker’s chorus frogs are the vocal chirps often heard in and around its midwestern ponds and creeks. The sound of these singing frogs is described as the ring of sleigh bells. Compared to Pseudacris ornata, Strecker’s chorus frogs have calls at a lower frequency. Strecker’s chorus frogs have a dominant frequency of calls at 2280 cps, while P. ornata has dominant frequency of 2640 cps. To the human ear, the singing of an entire population sounds like chaos, however, males wait until just after another to make their own note. These frogs can distinguish among the calls of individual males.

These songs are emitted only by males and are usually used to attract females. The call is also made by one male to inform another competing male of his presence and to establish his territory. While these calls are produced mostly at night during the height of mating season, they sometimes can be heard during the day. Mating calls typically only happen at night. Each call period consists of a refractory phase, excitatory phase, and a call activation phase. The refractory phase is between the beginning of the period and up to 80 milliseconds before the next call. The excitatory phase is between the end of refractory phase and the beginning of the call activation phase, and it is here where the lengthening of the call occurs. The call activation phase can last 5 to 30 milliseconds of the entire call period. Most call periods can last up to 50 milliseconds. In addition to vocalizations, mating uses pheromones to initiate the act and tactile information to excrete the sperm and eggs. (Blair and Littlejohn, 1960; Brown, 1988; Conant and Collins, 1998; Loftus-Hills, 1973; Michaud, 1962)

Food Habits

As tadpoles, Strecker's chorus frogs generally act as herbivores. Tadpoles scavenge for detritus and algae. However, tadpoles are known to be cannibalistic when resources are scarce. As adults, the diet of these frogs change dramatically. Adults are carnivorous, feeding primarily at night, and eating a wide variety of arthropods, such as mayflies (Ephemeroptera) and other invertebrates, such as crayfish (Orconectes). Younger, smaller frogs have a diet comprised of mainly smaller insects, including larval forms of midge flies (Chironomidae) and water mites (Hydrachnidiae). Prey capture techniques are largely opportunistic and, as these frogs are not quick, prey is often slow (such as larvae). Strecker's chorus frogs are also adapted to foraging underground. They have large front legs, allowing them to burrow front first and capture any food found in the process of burrowing. (Brown, 1978; Conant and Collins, 1998; Trauth, et al., 2006a)

  • Animal Foods
  • amphibians
  • insects
  • terrestrial non-insect arthropods
  • Plant Foods
  • algae

Predation

An abundance of predators are found in P. streckeri habitats. These include garter snakes, raccoons, snapping turtles, dragonfly larvae, and a wide variety of birds, fish, other snakes, and mammals. A predator deterrent used by Strecker's chorus frogs is their ability to burrow and stay burrowed for long amounts of time. Their ability to eat underground allows them to stay buried and essentially only come out to mate. Tadpoles will seek shelter in or around any underwater structure; they often are found among aquatic plants. (Blair and Littlejohn, 1960; Gridi-Papp and Gridi-Papp, 2005; Loftus-Hills, 1973)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Since most of their time is spent underground, the ecosystem impact of Strecker’s chorus frogs is not well known. (Clark, 1974)

Economic Importance for Humans: Positive

Since Strecker’s chorus frogs remain underground for most of the year, little is known about this species. However, they have been the focus of numerous research studies. Like all members of the family Hylidae, P. streckeri feeds on small insects, such as mosquitoes, which can be beneficial in preventing the spread of mosquito-born illnesses to humans. (Wells, 2007)

Economic Importance for Humans: Negative

Pseudacris streckeri has no adverse effects on humans.

Conservation Status

Populations of Strecker's chorus frogs are not believed to be under any major threats currently. This species of chorus frog is ranked as "Least Concern". However, the US Fish & Wildlife Service profile for this species does list them as "a species of concern". The conservation status of P. illinoensis (Illinois chorus frog) is of concern due to agricultural development in their habitat. Development has destroyed over half of P. illinoensis habitat; these habitats have been converted largely to agricultural fields and urban developments. (Handy, 2011; Trauth, et al., 2006b)

Contributors

Blake Hintz (author), Radford University, Taryn Yezek (author), Radford University, Christine Small (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

choruses

to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

detritus

particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

freshwater

mainly lives in water that is not salty.

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

marsh

marshes are wetland areas often dominated by grasses and reeds.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

References

Blair, F., M. Littlejohn. 1960. Stage of speciation of two allopatric populations of chorus frogs (Pseudacris). Evolution, 14/1: 82-87.

Brown, L. 1988. Distribution, habitat and calling season of the Illinois chorus frog (Pseudacris streckeri illinoensis) along the lower Illinois river. Biologial notes, 132: 12-13.

Brown, L. 1978. Subterranean feeding by the chorus frog Pseudacris streckeri (Anura: Hylidae). Herpetologica, 34/2: 212-216.

Brown, L., H. Jackson, J. Brown. 1972. Burrowing behavior of the chorus frog, Pseudacris streckeri. Herpetologica, 25/4: 325-328.

Carter, J., V. Resh. 2001. After site selection and before data analysis: sampling, sorting, and laboratory procedures used in stream benthic macroinvertebrate monitoring programs by USA state agencies. Journal of the North American Benthological Society, 20/4: 658-682.

Clark, D. 1974. The western ribbon snake (Thamnophis proximus): ecology of a Texas population. Herpetologica, 30: 372–379.

Conant, R., J. Collins. 1998. Field guide to reptiles and amphibians. New York, NY: Houghton Mifflin Company.

Dorcas, M., W. Gibbons. 2008. Frogs and toads of the southeast. Athens, GA: University of Georgia Press.

Elliot, L., C. Gerhardt, C. Davidson. 2009. The frogs and toads of North America: A comprehensive guide to their identification, behavior, and calls. New York, New York: Houghton Mifflin Company.

Gray, P., E. Stegall. 1986. Distribution and status of Strecker's chorus frog (Pseudacris streckeri streckeri) in Kansas. Transactions of the Kansas Academy of Science, 89/3: 81-85.

Gridi-Papp, M., C. Gridi-Papp. 2005. Abnormal digits in Strecker's chorus frogs (Pseudacris streckeri, hylidae) from central Texas. The Southwestern Naturalist, 50/4: 490-494.

Grubb, J. 1973. Olfactory orientation in Bufo woodhousei floweri, Pseudacris clarki and Pseudacris streckeri. Animal Behaviour, 21/4: 726-732.

Hammerson, G. 2004. "Pseudacris streckeri" (On-line). IUCN Red List of Threatened Species. Version 2011.1. Accessed February 17, 2011 at http://www.iucnredlist.org/apps/redlist/details/55898/0.

Handy, J. 2011. The secret life of the Illinois chorus frog. Outdoor Illinois, 29/3: 9-11.

Hazen, W. 1949. Handbook of frogs and toads. Ithaca, NY: Hazen Press.

Jameson, D. 1956. Survival of some central Texas frogs under natural conditions. Copeia, 56/1: 55-57.

Lenat, D. 1988. Water Quality Assessment of Streams Using a Qualitative Collection Method for Benthic Macroinvertebrates. Journal of the North American Benthological Society, 7/3: 222-223.

Loftus-Hills, J. 1973. Analysis of an acoustic pacemaker in Strecker's chorus frog, Pseudacris streckeri (Anura: Hylidae). Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, 90/1: 75-87.

Long, K. 1999. Frogs: A wildlife handbook. Boulder, Colorade: Johnson Books.

McCallum, M., S. Trauth. 2001. Are tadpoles of the Illinois chorus frog (Pseudacris streckeri illinoensis) cannibalistic?. Tranactions of the Illinois state academy of science, 94/3: 171-178.

Michaud, T. 1962. Call discrimination by females of the chorus frogs, Pseudacris clarki and Pseudacris nigrita. Copeia, 1962/1: 213-215.

Packard, G., J. Tucker, L. Lohmiller. 1998. Distribution of Strecker's chorus frogs (Pseudacris streckeri) in relation to their tolerance for freezing. Journal of Herpetology, 32/3: 437-440.

Ralin, D., J. Rogers. 1972. Aspects of tolerance to desiccation in Acris crepitans and Pseudacris streckeri. Copeia, 1972/3: 519-525.

Trauth, J., S. Trauth, R. Johnson. 2006. Best management practices and drought combine to silence the Illinois chorus frog in Arkansas. Wildlife Society Bulletin, 34/2: 514-518.

Trauth, J., S. Trauth, R. Johnson. 2006. Best management practices and drought combine to silence the Illinois chorus frog in Arkansas. Wildlife Society Bulliten, 34/2: 514-518.

Tucker, J. 1995. Early post-transformational growth in the Illinois chorus frog(Pseudacris streckeri illinoensis). Journal of Herpetology, 29/2: 314-314.

Turner, F. 1962. The demography of frogs and toad. The Quarterly Review of Biology, 37/4: 303-314.

Walls, J. 1997. The guide to owning American treefrogs. Neptune City, NJ: Tfh Pubns Inc.

Wells, K. 2007. The ecology & behavior of amphibians. Chicago, IL: The University of Chicago Press.

Wiggins, G., R. Mackay. 1978. Some Relationships between Systematics and Trophic Ecology in Nearctic Aquatic Insects, with Special Reference to Trichoptera. Ecology, 59/6: 1211-1220.

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