Photo Credit: John Jensen
SCIENTIFIC NAME: Hyla andersonii (Baird)
OTHER NAMES: Anderson’s Treefrog.
STATUS: Known from fewer than 20 isolated locations in southern Escambia, Covington, and Geneva counties as part of a disjunct population shared with the Florida Panhandle. Habitat quality and quantity declining, especially on private lands. HIGHEST CONSERVATION CONCERN.
DESCRIPTION: Adults small (about 3.8 cm [1.5 in.] long), plump, and green, with round, expanded toepads for climbing. Back and upper surfaces of legs pea-green, but may become dark olive-green under certain conditions of stress or weather. Sides with chocolate-brown to plum-colored band extending from nostril to hind limb that is delineated from green dorsum by a narrow, lemon-yellow border. Belly skin granular and white. Armpits, inside surfaces of hind legs, and lower sides have several bright yellow-orange spots that are usually concealed unless frog is moving (Gosner and Black 1967). Females slightly larger than males; recently transformed and young frogs identical to adults. Call consists of a series of high-pitched “quanking” notes repeated rapidly in sequence about 0.4 seconds apart for several seconds duration. Tadpoles up to 3.8 centimeters (1.5 inches) long and dark olive with black spots scattered over back. Belly greenish yellow. Tail musculature, and to a lesser extent the tail crests, with well-defined dark blotches and spots coalesced along the upper sides of the tail musculature to form a distinctive black line with irregular borders beginning just behind the body and progressing uninterrupted about halfway down tail (Means and Longden 1976).
DISTRIBUTION: Discontinuous in Atlantic Coastal Plain from New Jersey to South Carolina and found in the Gulf Coastal Plain in the Florida Panhandle and a small area of southern Alabama. An intensive search in Alabama revealed it at only 22 sites in southern Covington, Escambia, and Geneva Counties (Mount 1980b, Moler 1981). An additional 13 sites were subsequently found in Conecuh National Forest (Jensen 1991).
HABITAT: Hillside seepage bogs along gently sloping, small stream valleys typical in Alabama. Usually upper slopes historically supported longleaf pine/wiregrass forest that graded downslope into an acid wetland herb bog, with pitcher plants, sundews, and sphagnum moss. Further downslope beyond the herb bog and along the stream typically was an evergreen shrub bog consisting predominantly of titis, large gallberry,and other leathery-leafed shrubs. Breeding sites and larval habitats are small pools of clear, cool seepage water along tiny rivulets on boggy hillsides. Pools usually less than 25 centimeters (10 inches) deep and contain a diverse aquatic flora of delicate plants (sphagnummoss, pipeworts, etc.; Means and Longden 1976). Some of the Alabama habitats are atypical in that either planted slash pine is the dominant woody plant of the “shrub bog” component, or in that fire exclusion has enabled an overstory of mesophytic hardwood trees to develop (Mount 1980b).
LIFE HISTORY AND ECOLOGY: Males call from April to September. Tadpoles have been collected from early May to the last week in August. By the end of September, all larvae have probably transformed. Based on laboratory growth rates, larvae of one summer are capable of reaching adult size by the next, but this is not confirmed in the field. Males call from low perches (ground level to about 1.2 m [3.9 ft.] high) in vegetation surrounding breeding sites. Females deposit 200 or more eggs in batches of four to nine while amplexed with a male that fertilizes the eggs as they are extruded (Means and Longdon 1976). After hatching in three to four days, larvae soon begin an aquatic life grazing on algae and other plant matter. The frogs and tadpoles are very sensitive to changes in their environment. Attempts to rear tadpoles in captivity in tap water or even in water from the habitat often are unsuccessful. Captive adults that are especially well cared for usually die after a few months or less. Choruses rarely exceed 10 males. A locality having audible males at one part of the breeding season may be silent at another, even though the species is calling elsewhere (Means and Moler 1979). Most knowledge based on information obtained at breeding sites found by locating calling males. This represents only a fraction of the life history and ecology of the species. Little known of the ecology of nonbreeding adults.
BASIS FOR STATUS CLASSIFICATION: The remarkable distribution of disjunct populations makes it a subject valuable to the study of biogeography and evolution (Means and Longden 1976). Also, the Alabama-Florida populations differ significantly from those of the Atlantic Coastal Plain in aspects of morphology, ecology, call structure, and isozymes (Karlin et al. 1982). The ecology, distribution, and habitat suggest that the species was formerly more widespread during milder, wetter climates. Living populations could be considered “physiological relicts,” possibly best adapted to some Pleistocene climates. Local populations are subject to extirpation. Of 10 Conecuh National Forest populations documented in 1980, four could not be confirmed as extant a decade later (Jensen 1993). The assigned priority status is warranted because fewer than 30 localities in one small area are known in Alabama, and the only efforts to preserve the species’ delicate and rare habitats occur in a few places in Conecuh National Forest. In Florida, the frog was found to be more common and widespread than was believed earlier, resulting in its being removed from federal protection. Nevertheless, Florida officially considers it a Species of Special Concern.
Author: D. Bruce Means