Hyla avivoca Viosca, 1928
1. Historical versus Current Distribution. Bird-voiced treefrogs (Hyla
avivoca) range from extreme southwestern South Carolina, southwest across
Georgia to the Florida Panhandle, west across the Gulf Coast (roughly including the
southern half of Alabama and statewide in Mississippi) to the east side of the
Mississippi River drainage, and north through western Kentucky and Tennessee to extreme
southern Illinois (Drury and Gessing, 1940; Gentry, 1955; Smith, 1961, 1966a; Barbour,
1971; Mount, 1975; Martof et al., 1980; Ashton and Ashton, 1988; Conant and Collins,
1991; Redmond and Scott, 1996). Bird-voiced treefrogs also occur west of the
Mississippi River, in isolated populations in central and northwestern Louisiana, the Red
River Drainage of extreme southeastern Oklahoma, and in eastern, central, and southern
Arkansas (Blair and Lindsay, 1961; Krupa, 1986c; Dundee and Rossman, 1989; Trauth,
2. Historical versus Current Abundance. Historical abundance is unknown and
therefore cannot be compared with current abundance. Bird-voiced treefrogs are
currently listed as Threatened in Illinois (Redmer and Kruse, 1998), where many remaining
colonies are isolated due to past drainage of hardwood swamps.
3. Life History Features.
Reproduction is aquatic.
i. Breeding migrations. Males are stimulated by warm temperatures and will chorus
by day in treetops in the same swamps used for breeding. Chorusing often begins
≥ 1 mo before breeding (Dundee and Rossman, 1989; Redmer et al., 1999a), an indication
that males spend the entire year in the vicinity of the breeding site. The
prolonged breeding season begins in late spring (April in the southern part of the range;
May in the north) and lasts throughout much of the summer (Fortman and Altig, 1974;
Mount, 1975; Krupa, 1986c; Ashton and Ashton, 1988; Trauth, 1992; Redmer et al.,
1999a). In Illinois, chorusing commences at dusk and lasts until temperatures drop
below about 16 ˚C or until most males are paired; few individual males chorus after
midnight. Individuals are occasionally found alive on roads adjacent to swamps in
which they breed (Redmer et al., 1999a,b).
ii. Breeding habitat. Hardwood swamps and forested flood-plains, especially those
consisting of cypress (Taxodium distichum) and tupelo gum (esp.
Nyssa aquatica) trees (Viosca, 1928; Fouquette and Dalahoussaye, 1966;
Trauth and Robinette, 1990; Redmer et al., 1999a). Most males call from elevated
positions in trees and other woody vegetation over water (Parker, 1951; Secor, 1988;
Trauth and Robinette, 1990; Redmer et al., 1999a). Females approach and touch
calling males to stimulate amplexus (Redmer, 1998), or males may initiate amplexus with
approaching females (Trauth and Robinette, 1990).
i. Egg deposition sites. Amplexed pairs have been observed on the branches of
trees and shrubs, in reeds (Phragmites sp.), willow thickets, and a shrubby farm
pond (Parker, 1951; Turnipseed and Altig, 1975; Trauth and Robinette, 1990; Redmer,
1998). After amplexus begins, the female descends (carrying the male) head first to
the water surface to oviposit. When the female reaches the water she rotates and
backs her posterior into the water. Oviposition takes place with the female
clinging to the vegetation, and eggs sink to the bottom substrate (Redmer, 1998).
ii. Clutch size. I have examined clutch size in 12 females and found a mean of 632
eggs (range 409–811; unpublished data). Because of the prolonged breeding
season and presence of yolked ovarian eggs in individuals that have oviposited, it is
possible that females of this species lay multiple clutches (as do females of some other
North American Hyla), though direct evidence of this is lacking (Trauth and
Robinette, 1990; Redmer, 1998a).
Larvae/Metamorphosis. Tadpoles have been collected in the water under the perches
where amplexus occurs.
i. Larval period. Lasts approximately 30 d (Hellman, 1953; Volpe et al., 1961;
Trauth and Robinette, 1990).
Habitat. Juveniles are sometimes found perched on low vegetation or on the ground
adjacent to swamps used for breeding (Redmer et al., 1999a).
Habitat. Prior to and following the chorusing season, adults are sometimes found
perched on low vegetation, on the ground, under logs, in shrub thickets, or in tree
crevices in or adjacent to swamps used for breeding (Parker, 1951; Dundee and Rossman,
1989; Redmer et al., 1999a).
F. Home Range
Territories. Males combat to defend chorusing sites from other males (Altig, 1974).
Aestivation/Avoiding Dessication. Unknown.
Migrations. Unknown. Daytime chorusing in treetops over the same swamps used
for breeding might indicate that males spend the entire year in the vicinity of the
(Hibernation). Conditions under which torpor occurs in wild are unknown.
Captive individuals refuse food and become sluggish; their movement is noticeably
uncoordinated at air temperatures below 15 ˚C (unpublished data).
Associations/Exclusions. Bird-voiced treefrogs comprised 0.8% of the total
population of three species (also including cricket frogs [Acris
crepitans] and green treefrogs [H. cinerea]) of hylid tadpoles
in an upland pond in Mississippi (Turnipseed and Altig, 1975). In Illinois, large
choruses of bird-voiced treefrogs are most often associated with choruses of cricket
frogs, bullfrogs (Rana catesbeiana), and green frogs (R.
clamitans; Redmer et al., 1999a). Males may chorus with or near choruses of
green treefrogs, though male perch sites rarely overlap (Turnipseed and Altig, 1975;
Secor, 1988; Redmer et al., 1999a). While it has been reported that green treefrogs
often predominate in more shallow water areas with emergent herbaceous vegetation,
whereas bird-voiced treefrogs prefer deeper areas with woody structure (Turnipseed and
Altig, 1975; Redmer et al., 1999a), the opposite also has been reported (Secor,
1988). Differences in chorus sites and breeding call may usually act as isolating
mechanisms, but hybridization with other Hyla is known to occur naturally and
has been demonstrated in the lab (Mecham, 1960a, 1965; Fortman and Altig, 1974).
L. Age/Size at
Reproductive Maturity. Mature females from Illinois were found to be 2–4 yr
old (unpublished skeletochronology data). Male ages at sexual maturity are
unknown. Females (32–52 mm SVL) are larger than males (28–39 mm SVL;
Neill, 1948a; Wright and Wright, 1949; Smith, 1961; Trauth and Robinette, 1990; Redmer et
al., 1999a; unpublished data).
Maximum known age is 4 yr for females (unpublished data). Male longevity is
Behavior. Individuals feed primarily (if not entirely) on arboreal arthropods
(Jamieson et al., 1993; Redmer et al., 1999b).
Observations of predation in the wild are unknown, but birds, water snakes, and other
vertebrates probably prey on juveniles and adults. Tadpoles are probably consumed
by aquatic invertebrates and vertebrates.
Protozoans, trematodes, and cestodes have been reported (Reiber, 1941; C.T. McAllister et
al., 1993a). A report of a trypanosome (Woo and Bogart, 1984) is questionable
because the host reportedly was collected in Ohio, a state from which this species has
not been documented.
4. Conservation. Bird-voiced treefrogs are currently listed as Threatened in
Illinois, where many remaining colonies are isolated. They have fairly specific
habitat characteristics, including bottomland hardwood swamps and forested flood-plains,
especially those consisting of cypress and tupelo gum. This habitat specificity may
have had, and may continue to have, consequences for the conservation of this
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Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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