Anaxyrus quercicus is a very small toad with a maximum snout-vent length of 32 mm. The head is short with a pointed snout. Dorsal coloration is brown to silver grey with a cream to orange colored mid- dorsal stripe. There are 4-5 dark unconnected blotches on either side of this stripe. The ventral side is granular and cream colored. There is black banding on the arms and legs. The parotoids are tear-shaped, and descend on the sides to the inferior edge of the tympanum.
Oak toads are found in the coastal plains of the southeastern United States. They are found from the southern tip of Florida to the southern portion of Virginia and to parts of eastern Louisiana.
Biogeographic Regions: nearctic (Native )
Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Coastal Plain from southeastern Virginia south through all of Florida and west to the Mississippi River in Louisiana (Conant and Collins 1991).
Distribution and Habitat
Distribution is restricted to the southeastern region of the United States: east and south of the Fall Line and east of the Mississippi River.
endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Anaxyrus quercicus is the smallest toad species in North America, ranging from 1.9 to 3.3 cm. It is so small that adults found in the wild were commonly classified as “half-grown” or “juvenile” southern toads (Bufo lentiginosus). They have a short head with a pointed nose and the short, flat body is black or brown in color (color can change with temperature) with a long dorsal stripe that may be white, cream, yellow, or orange. There are 4 to 5 pairs of dark blotches found on the back. The back is finely tuberculate, with the fine bumps (red, orange or reddish-brown in color) giving it a rough texture. The underside is grayish white and has no blotches, but is covered in tubercles. Oak toads have elongated, teardrop-shaped paratoid glands that extend down either side. These glands house a poisonous fluid used deter predators. Males can be distinguished by their dark, dusky colored throats.
Range length: 19 to 33 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous
Sexual Dimorphism: female larger; sexes shaped differently
Length: 3 cm
Oak toads are generally found in moist, grassy areas near pine or oak savannahs with sandy soil. They are also found in vernal pools and freshwater wetlands. They breed in shallow pools, ditches, and ponds.
Habitat Regions: temperate ; terrestrial ; freshwater
Terrestrial Biomes: savanna or grassland ; forest
Aquatic Biomes: lakes and ponds; rivers and streams; temporary pools
Habitat and Ecology
Comments: Sandy pine flatwoods and oak scrub; open pine and pine-oak woods; pine or oak savannas with sandy soils; maritime forests. Occurs on some barrier islands in South Carolina. Seems to favor open-canopied pine flatwoods with grassy ground cover. When inactive, burrows underground or hides under surface objects. Eggs and larvae develop in rain pools, ditches, cypress and flatwoods ponds, and other flooded areas.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Migrates between breeding pools and nonbreeding terrestrial habitats.
Oak toads are predaceous and feed primarily on terrestrial insects and other small arthropods.
Animal Foods: insects; terrestrial non-insect arthropods
Primary Diet: carnivore (Insectivore , Eats non-insect arthropods)
Comments: Metamorphosed toads eat a variety of small terrestrial invertebrates such as ants and beetles. Larvae eat organic debris, algae, and plant tissue.
Although smaller than other toads, the Oak Toad still plays a crucial role in insect population control.
The primary predators of oak toads are snakes, particularly hognosed snakes (Heterodon platirhinos), specialized for eating toads. Other predators of oak toads are garter snakes (Thamnophis sirtalis) and gopher frogs (Lithobates capito).
- hognosed snakes (Heterodon platirhinos)
- garter snakes (Thamnophis sirtalis)
- gopher frogs (Lithobates capito)
Anti-predator Adaptations: cryptic
100,000 - 1,000,000 individuals
Comments: Total adult population size is unknown but likely exceeds 100,000.
In Florida, density was estimated at 2/100 sq m (Hamilton 1955).
Life History and Behavior
Male oak toads make a high-pitched, bird-like chirping calls to attract females. Oak toads perceive their environment through visual, auditory, tactile, and chemical senses.
Communication Channels: acoustic
Other Communication Modes: choruses
Perception Channels: visual ; tactile ; acoustic ; chemical
Comments: Most active during the breeding period. More diurnal than most toads. Primarily diurnal except when breeding (Mitchell 1991).
In the span of two months, tadpoles hatch from their eggs and go through metamorphosis, becoming adult toads. Tadpoles have a grayish olive or grape green color to the body due to close set dots against a black background. The underside has a pale purplish color. the tail has 6-7 black saddles (coloration that wraps around the tail to a degree). Juvenile toads remain near the natal pond for a few days before moving to land, where they will spend the majority of their time.
Development - Life Cycle: metamorphosis
Oak toad lifespans are not well known.
Status: captivity: 1.9 years.
Males arrive before females at shallow, semi-permanent or temporary ponds, and roadside drainage ditches. At breeding ponds males establish territories and begin calling females with a high-pitched chirp. Approximately 100-250 eggs are laid at a time in long strings, held together by a gelatinous material, and either float or stick to surfaces. Fertilization takes place externally when the male frog releases his sperm in the vicinity of the eggs. In the case of a testicular malfunction, male oak toads have an ovary that will become functional, allowing them to breed as females.
Mating System: polygynandrous (promiscuous)
Male and female oak toads form a pair when the male grabs onto the female from behind in a position referred to as amplexus. The male stays attached to the female until she releases her eggs into the water. The female emits several eggs and then the male releases sperm into the water. The female will continue to release eggs. The eggs are released in bars containing 4-6 eggs apiece. Each female will lay about 700 eggs in total in a single season. These eggs will hatch within 3 to 3.5 days and develop into adult oak toads within 2 months.
Breeding interval: Oak toads are seasonal breeders and breeds once per year.
Breeding season: Oak toads breed from April to September or October. The mating season often begins with the arrival of warmer temperatures and thunderstorms. The interval of ovulation is approximately late May-mid August.
Average number of offspring: 700.
Range time to hatching: 72 to 80 hours.
Average age at sexual or reproductive maturity (female): 2 months.
Average age at sexual or reproductive maturity (male): 2 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
The extent of female energy investment is great during the ovulation and mating periods, as many females are found dead during these periods due to either the rigors of pair formation or energy investment in the laying of eggs. Once the eggs are fertilized and attached to a surface, there is no further parental care.
Parental Investment: no parental involvement; pre-fertilization (Provisioning)
Lays clutch of several hundred eggs, in small strands, April-October, usually coincident with heavy rains. Larval period lasts about 2 months.
Molecular Biology and Genetics
Statistics of barcoding coverage: Anaxyrus quercicus
Public Records: 0
Specimens with Barcodes: 1
Species With Barcodes: 1
Oak toad populations are declining throughout many states. In Virginia it is listed as a species of special concern (one that is not yet threatened but is expected to be in the near future). Also, in North Carolina, it is on the watch list for species that may be facing problems in the near future. A possible cause for decreases in oak toad populations is the clearing of the savannah forest habitats they prefer.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Apparently secure in much of the historical range in the southeastern United States; however, the species has declined locally as a result of drainage of wetlands, forest management practices, and urbanization.
Intrinsic Vulnerability: Moderately vulnerable
Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
Global Short Term Trend: Relatively stable to decline of 30%
Comments: In Florida, seemingly less common than historically, but the species remains common to abundant in many areas (Bartlett and Bartlett 1999).
Global Long Term Trend: Relatively stable to decline of 50%
Comments: Likely relatively stable in extent of occurrence, unknown level of decline in population size, area of occurrence, and number/condition of occurrences.
Degree of Threat: Medium
Comments: Does not appear to thrive in urban and suburban areas but may remain common in agricultural areas (Bartlett and Bartlett 1999). In some areas, threatened by conversion of habitat to dense monocultures of loblolly pine and by continued draining of surface waters in remaining stands of pine savanna and pine-oak (Mitchell 1991).
Relevance to Humans and Ecosystems
There are no known negative impacts of oak toads on humans.
Oak toads help control population levels of insects and other small arthropods.
Positive Impacts: controls pest population
The oak toad (Anaxyrus quercicus) is a species of toad in the family Bufonidae. It is endemic to the coastal regions of southeastern United States. It is regarded as the smallest species of toad in North America, with a length of 19 to 33 mm (0.75 to 1.30 in).
The oak toad can be identified by its light mid-dorsal stripe, variable brown and black spots, and proportionally large parotoid glands. One of the most remarkable features of this species is its small adult size relative to other toads.
The male can be distinguished from the female by its clear white belly and a slightly distended, loose flap of skin beneath the mouth, which expands into the vocal sac. The female has a dark-spotted belly and lacks a vocal sac.
Habitat and distribution
The toad's range extends across the coastal plains of the southeastern United States from eastern Louisiana to southeast Virginia and south throughout Florida.
It is mostly diurnal and spends much of its time burrowed into the loose soil of its habitat. It may remain in its burrow during the winter, often in hibernation.
Breeding takes place in shallow pools that accumulate during heavy rains. The male expands his distinctive elongated vocal sac to produce a chirping call. The breeding season extends from April to October, peaking early on. Heavy, warm spring rains stimulate mating behavior.
An average of 300-500 eggs are laid in short strands of 3 to 8 eggs each, with each egg about a millimeter wide. The strands are attached to vegetation, usually submerged blades of grass 4 to 12 cm (1.6 to 4.7 in) beneath the surface. Energy investment in producing this quantity of eggs is significant, and many females are found dead during the mating season due to the rigors of the process. Fertilization takes place externally, with sperm being released in the vicinity of the eggs. As with other species of toad, the male oak toad has a Bidder's organ, which can become a functional ovary in the event of testicular malfunction.
Eggs develop quickly, hatching in a mere 24 to 36 hours.. The tadpole reaches a maximum length of 18 to 19.4 mm (0.71 to 0.76 in). It is grayish olive or grape-green dorsally and purplish ventrally. The tail has 6 or 7 black saddle marks.. The tadpole completes metamorphosis into a juvenile toadlet in 4 to 6 weeks, and it reaches adulthood and sexual maturity at 1.5 to 2.3 years of age.
As with many bufonids, the oak toad inflates its body in unkenreflex when confronted by a potential predator. It secretes toxins from its parotoid glands and urinates when threatened. The male may chirp as a response to predators. Eggs also appear to have some toxic properties.
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