Pseudacris streckeri
Strecker's Chorus Frog

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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)

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

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)

Pseudacris streckeri has no adverse effects on humans.

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)