Little Grass Frog
© 2009 Stephen Bennett (1 of 12)
Pseudacris ocularis (Bosc and Daudin, 1801)
John B. Jensen1
1. Historical versus Current Distribution. Little grass frogs (Pseudacris ocularis) are found in the southeastern Coastal Plain (Harper, 1939) from southeastern Virginia to the southern tip of Florida, inland to the Fall Line and west to Choctawhatchee Bay in the Florida Panhandle (Moler, 1982; Conant and Collins, 1991; Jensen, 1994). Harper (1935) reported little grass frogs from Key West, Florida, however this record was challenged by Duellman and Schwartz (1958). A record of little grass frogs from Texas (Burt, 1936) was later determined to be a misidentified western chorus frog (Pseudacris triseriata; Franz and Chantell, 1978). Brandt (1936a) reported little grass frogs from Mississippi that were almost certainly misidentifications. A report of little grass frogs from the upper Gulf Coastal Plain of Georgia, specifically Fort Benning Military Reservation (Goodman, 1958), is quite distant from the nearest confirmed record. Many colleagues and I have spent considerable time in this area without encountering little grass frogs, therefore this record should be considered suspect as well. Misidentifications are not surprising, especially when one considers that several authorities have addressed possibilities that the original description of little grass frogs was based on a specimen of Acris (Harper, 1939; Mittleman, 1946). Indeed, some field guides state possible confusion between juvenile Acris, other Pseudacris spp., and adult little grass frogs (including Martof et al., 1980; Ashton and Ashton, 1988). Unless suspected misidentifications were in fact little grass frogs, there is no information available to indicate a change in this species’ distribution.
2. Historical versus Current Abundance. These are common frogs throughout much of their range, and no significant change in their abundance has been noted.
3. Life History Features.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Throughout most of their range, little grass frogs breed from January–September (Harper, 1939) with a peak in Florida during March–April (Ashton and Ashton, 1988). Little grass frogs breed throughout the year in Florida (Carr, 1940a; Einem and Ober, 1956).
ii. Breeding habitat. Little grass frogs breed in shallow, grassy, rain-filled depressional wetlands, including roadside ditches and semi-permanent ponds (Harper, 1939; Mount, 1975; Gibbons and Semlitsch, 1991).
i. Egg deposition sites. Eggs are deposited on the pond bottom or on submerged vegetation (Wright, 1923).
ii. Clutch size. Wright and Wright (1949) reported that little grass frogs deposit about 100 eggs, although Bartlett and Bartlett (1999a) suggested that > 200 eggs may be laid by a single female. Eggs are laid singly (Wright, 1923) or in several clusters of 25 or more (Bartlett and Bartlett, 1999a). Hatching occurs in 1–2 d (Ashton and Ashton, 1988).
i. Length of larval stage. From 45–70 d (Wright and Wright, 1949).
ii. Larval requirements.
a. Food. Unknown, but tadpoles likely graze on algae.
b. Cover. Tadpoles are most readily captured in relatively dense emergent and submerged vegetation.
iii. Larval polymorphisms. Unknown and unlikely for this species.
iv. Features of metamorphosis. Newly transformed froglets are 7–9 mm SVL (Wright, 1932; Gosner and Rossman, 1960).
v. Post-metamorphic migrations. Unknown.
D. Juvenile Habitat. Unknown, but likely similar to adults.
E. Adult Habitat. Little grass frogs use grass, sedge, and/or sphagnum habitats in or near cypress ponds, bogs, pine flatwoods and savannas, river swamps, and ditches (Harper, 1939; Wright and Wright, 1949; Mount, 1975; Gibbons and Semlitsch, 1991). They have been found calling from vegetation within brackish ditches (Neill, 1958a), though it is unknown whether reproduction is attempted or successful in such waters. Adults are capable of climbing vines, tree trunks, and bushes to a height of 1.5 m high or more (Harper, 1939; Wright and Wright, 1949). Harper (1939) found an inactive individual beneath a log in a dried-up cypress pond. Little grass frogs are often active both day and night. There is no information to indicate differing habitat characteristics between the sexes.
F. Home Range Size. Unknown.
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. In some areas, little grass frogs are active year-round (Carr, 1940a; Einem and Ober, 1956).
I. Seasonal Migrations. Related to breeding (see “Breeding migrations" above).
J. Torpor (Hibernation). In some areas, little grass frogs are active throughout the year (Carr, 1940a; Einem and Ober, 1956). In fact, Harper (1939) stated that except “possible suspension of activity during cold spells of a few days’ duration,” little grass frogs doubtfully hibernate in the Okefenokee (southeastern Georgia) region.
K. Interspecific Associations/Exclusions. Little grass frogs breed along with other chorus frogs (Ashton and Ashton, 1988) including ornate chorus frogs (P. ornata; Mount, 1975) and southern chorus frogs (P. nigrita), as well with other frogs such as southern leopard frogs (Rana sphenocephala), Cope's gray treefrogs (Hyla chrysoscelis), and southern cricket frogs (Acris gryllus; personal observations).
L. Age/Size at Reproductive Maturity. Little grass frogs are the smallest North American frog (Conant and Collins, 1991) with males ranging in size from 11.5–15.5 mm and females 12.0–17.5 mm SVL (Wright and Wright, 1949), although the maximum reported size is 20 mm (Franz and Chantell, 1978).
M. Longevity. Unknown.
N. Feeding Behavior. Marshall and Camp (1995) found that little grass frogs eat a wide variety of arthropods, especially insects. Springtails, hymenopterans (mainly ants and parasitic wasps), rove beetles, and homopterans, in that order, were the most abundant prey items consumed. Arachnids (primarily mites) were the only non-insect prey eaten. Most of the prey items are associated with leaf litter and/or soil, suggesting that little grass frogs frequently forage on the ground.
O. Predators. Owen and Johnson (1997) reported predation on a little grass frog by a wolf spider (Lycosa sp.) and suggested that little grass frogs may be important prey items for many species of vertebrates and invertebrates.
P. Anti-Predator Mechanisms. Despite their tiny size, little grass frogs can leap 15–22 cm (1–1.5 ft; Wright and Wright, 1949) to avoid predation. Little grass frogs are often cryptically colored similar to the dead grass and sedge blades in which they inhabit. The stripes through their eyes and along the sides may help to break-up their outline to visually oriented predators.
Q. Diseases. Unknown.
R. Parasites. The nematode Spironoura catesbianae has been found in little grass frogs (Yamaguti, 1961).
4. Conservation. Little grass frogs are not protected by either state or federal laws. They remain common throughout much of their range, and no substantial changes in their abundance have been noted.
John B. Jensen
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2018. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 18 Jul 2018.
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