The Lazy Naturalist

The Re-Enchantment of Nature - Sarasota, Florida

Oak Toad (Anaxyrus quercicus)

Key Profile Facts

  • Common Name: Oak Toad
  • Scientific Name: Anaxyrus quercicus
  • Family: Bufonidae (True Toads)
  • Size: It is North America’s smallest toad species, with adults measuring a mere 0.75 to 1.3 inches (19 to 33 mm) in length.
  • Identification: They are typically grey, brown, or nearly black with a distinctive, bright white, yellowish, or orange stripe running down the center of the back. They feature dark spots on their back and a conspicuously rough, wart-covered skin.
  • Geographic Range: Southeastern United States, stretching from southeastern Virginia down through the entire Florida peninsula, and west into coastal Louisiana.
  • Habitat: Commonly found in sandy soils, pine flatwoods, oak scrub, maritime forests, and sandhills. They require semi-permanent or ephemeral wetlands, such as shallow ditches and shallow ponds, for breeding.
  • Diet: Insectivore; they primarily consume a massive quantity of ants, along with other tiny invertebrates like beetles, spiders, and centipedes.

8 Most Interesting Things About Oak Toads

1. The Pint-Sized Titleholder

The Oak Toad holds the crown as the absolute smallest toad species in North America. Even when fully grown, an adult Oak Toad can easily sit on the face of a quarter with room to spare. Because of their tiny stature, they are frequently mistaken for the newly metamorphosed juveniles of larger toad species.

2. A Call Like a Baby Chick

Unlike the deep, resonant trills or guttural groans of larger amphibians, the Oak Toad has an extraordinarily high-pitched call. Their mating vocalization sounds nearly identical to the “cheep-cheep” of a newborn baby chicken. During the summer breeding season, a large chorus of these tiny toads can create a piercing, deceptively bird-like wall of sound near wetlands.

3. Dedicated Ant Commandos

While most toads are generalist predators that snap up any insect that fits in their mouth, Oak Toads are heavily specialized ant specialists. Because they are so small, ants make up the vast majority of their daily diet. They can routinely be found sitting right next to ant trails, casually zapping up dozens of passing ants with their sticky tongues.

4. Daytime Adventurers

Amphibians are notoriously nocturnal to avoid drying out, but Oak Toads frequently buck this trend. They are highly diurnal (active during the day) and are often seen actively hopping through leaf litter and pine needles under the bright morning or afternoon sun, hunting for insects.

5. Fire-Adapted Lifespans

Oak Toads are perfectly evolved to thrive in fire-dependent ecosystems like the longleaf pine flatwoods of the Southeast. They rely on periodic wildfires to keep the forest floor open and sunny. When a fire sweeps through, these clever toads escape the heat by burrowing into the loose, sandy soil or slipping into the underground tunnels dug by gopher tortoises.

6. Explosive Breeding Rituals

Oak Toads are “explosive breeders,” meaning their reproduction is intensely tied to heavy weather events. They spend much of the year quietly foraging, but the arrival of torrential summer rainstorms triggers them to converge on shallow, temporary pools all at once. They lay their eggs in small, fragile gelatinous strands attached to underwater vegetation, which hatch into tadpoles in just a few days.

7. Chemical Defense System

Despite their diminutive size, Oak Toads are not helpless snacks. Like all true toads, they possess parotoid glands behind their eyes that secrete toxins when they are stressed or attacked. This chemical defense makes them highly unpalatable to many small mammalian and avian predators, though certain species of snakes are immune to the poison.

8. Master Burrowers

Don’t let their small size fool you—Oak Toads are exceptional diggers. They utilize their hind legs to shuffle backward into loose sand, quickly vanishing beneath the surface to stay moist during dry spells or to hide from predators. They spend a significant portion of their lives underground, safe from the fluctuating elements of the southeastern landscape.

Oak toad
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Bufonidae
Genus: Anaxyrus
Species:
A. quercicus
Binomial name
Anaxyrus quercicus
(Holbrook, 1840)
Habitat range of A. quercicus
Synonyms

Bufo quercicus Holbrook, 1840

The oak toad (Anaxyrus quercicus) is a species of toad in the family Bufonidae that is endemic to the coastal regions of southeastern United States.[2][3] 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).[3]

Description

Adult male (left), female (right) - note the sharply contrasted ventral surface, the vocal sac on the male's throat, and the female's larger size
Smallest toad species in North America

The oak toad may be identified by its light mid-dorsal stripe, variable brown and black spots, and proportionally large parotoid glands. The female has a dark-spotted belly and the male has a clear white belly with a slightly distended, loose flap of skin beneath the mouth that expands into a vocal sac. As noted above, one of the most remarkable features of this species is its small adult size relative to other toads.

Habitat and distribution

The oak toad is native to the coastal regions of the southeastern United States, ranging from eastern Louisiana to southeast Virginia and south throughout Florida. It is found in a variety of habitats, including sandy pine flatwoods and oak scrub, open pine and pine-oak woods, pine or oak savanna with sandy soils, and maritime forests. Oak toads prefer open-canopied pine flatwoods with grassy ground cover. They are generally found in moist, grassy areas near pine or oak savannahs with sandy soil. They also are found in vernal pools and freshwater wetlands.[1][3][4]

Behavior

Oak toads are mostly diurnal and spend much of the time burrowed into the loose soil of their habitat. They may remain in burrows during the winter, often in hibernation.[5] The breeding season extends from April to October, peaking early on.[6][7] Breeding takes place in shallow pools that accumulate during heavy rains. Heavy, warm spring rains stimulate mating behavior.[8] The male expands his distinctive elongated vocal sac to produce a chirping call.

An average of 300 to 500 eggs are laid in short strands of three to eight eggs each, with each egg about a millimeter wide.[5] The strands are attached to vegetation, usually submerged blades of grass 4 to 12 cm (1.6 to 4.7 in) beneath the surface.[9][10] 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 may become a functional ovary in the event of testicular malfunction.[11][12]

Size comparison: adult male (left), female (right), USA quarter dollar
Oak toad tadpole

Diet

The oak toad is a small, terrestrial frog that feeds on a variety of insects and other small invertebrates. Its diet consists primarily of ants, beetles, and spiders, as well as other insects and arthropods. The oak toad spends much of its time foraging for food, using its long, sticky tongue to capture prey. The oak toad eats mainly small insects and other arthropods. The adult has a strong preference for ants.[5] While ants comprise a large percentage of its diet, the dietary preferences of B. quercicus are more diverse compared to those documented for numerous tropical anuran species. [13]

Life cycle

Eggs develop quickly, hatching in a mere 24 to 36 hours.[5] 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.[11][12]

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.[5] The length of the lifespan is unclear.[3] Although there are records of specimens living for four years in captivity,[9][11] the reported average lifespan in captivity is 1.9 years.[14]

Predation

The primary predators of the oak toad are snakes, particularly hognosed snakes, which are specialized for eating toads. Other predators include garter snakes and gopher frogs.[11][15] 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.[5]

Conservation

The oak toad is listed as "least concern" by the International Union for Conservation of Nature.[1] It may become rare locally due to habitat replacement by loblolly pine plantations, urbanization, and draining of surface water in its preferred wooded habitats.[1]

References

  1. 1 2 3 4 IUCN SSC Amphibian Specialist Group (2021). "Anaxyrus quercicus". IUCN Red List of Threatened Species. 2021 e.T54743A56952440. doi:10.2305/IUCN.UK.2021-3.RLTS.T54743A56952440.en. Retrieved 21 May 2023.
  2. ↑ Frost, Darrel R. (2016). "Anaxyrus quercicus (Holbrook, 1840)". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 30 January 2016.
  3. 1 2 3 4 Buckley, Ryan (2006). Dewey, Tanya; Fraser, Ann (eds.). "Anaxyrus quercicus". Animal Diversity Web. Retrieved 18 June 2024.
  4. ↑ Oak Toad, Bufo quercicus. Archived 2013-03-01 at the Wayback Machine USGS, Northern Prairie Wildlife Research Center, Checklist of Amphibian Species and Identification Guide. Retrieved 30 March 2013.
  5. 1 2 3 4 5 6 Lannoo, M. Amphibian Declines: The Conservation Status of United States Species. University of California Press. 2000. 432-33.
  6. ↑ Harper, F. 1931. A dweller in the piney woods. Science Monthly 32 176–81.
  7. ↑ Einem, G. E. and L. D. Ober (1956). "The seasonal behavior of certain Floridian Salientia". Herpetologica. 12 (3): 205–212. JSTOR 3889772.
  8. ↑ Wright, A. H. and A. A. Wright. 1949. Handbook of Frogs and Toads of the United States and Canada. Third edition. Comstock Publishing Associates, Ithaca, New York.
  9. 1 2 Ashton, R. E., Jr. and P. S. Ashton. 1988. Handbook of Reptiles and Amphibians of Florida: Part Three: The Amphibians. Windward Publishing, Miami, Florida.
  10. ↑ Hamilton, W. J. (1955). "Notes on the ecology of the oak toad in Florida". Herpetologica. 11 (3): 205–210. JSTOR 3889360.
  11. 1 2 3 4 Wright, A. 1932. Life Histories of the Frogs of Okefinokee Swamp, Georgia: North American Salientia (Anura) No. 2. United States: Cornell University Press.
  12. 1 2 Bufo quercicus. Archived 2007-11-10 at the Wayback Machine Virginia Department of Game & Inland Fisheries. 2004. Retrieved on 20 October 2005.
  13. ↑ Punzo, Fred. "AN ANALYSIS OF FEEDING IN THE OAK TOAD, BUFO QUERCICUS (HOLBROOK), (ANURA : BUFONIDAE)." Florida Scientist, vol. 58, no. 1, 1995, pp. 16–20. JSTOR, http://www.jstor.org/stable/24320633. Accessed 15 Jan. 2024.
  14. ↑ Bowler, J. K., 1975. Longevity of reptiles and amphibians in N. American collections as of 1 November 1975. Society for the Study of Amphibians and Reptiles, Miscellaneous Publications, Herpetological Circular 6 1-32.
  15. ↑ Behler, J. 1979. The Audubon Society Field Guide to North American Reptiles & Amphibians. New York: Chanticleer Press, Inc.

Further reading

source: https://en.wikipedia.org/wiki/Oak_toad

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