Distribution:
Found throughout the forested regions of the eastern third of Kansas. An isolated record exists at in Pratt County and may represent an accidental introduction at the state fish hatchery.
The tetraploid Gray Treefrog is morphologically indistinguishable from the diploid Cope’s Gray Treefrog and both species occupy similar ranges, however, the Cope’s Gray Treefrog is more widely distributed in Kansas. Gray Treefrogs are known from the Verdigris, Marias des Cygnes, and Kansas River drainages in Kansas.
Collins and Hillis (1985) and Hillis et al. (1987) analyzed the chromosomes of both species throughout Kansas. They found H. chrysoscelis throughout the eastern third of Kansas. H. versicolor was found in the Cross Timbers, lower Neosho River basin, the Marais des Cygnes, and the lower Kansas river basins. They determined the specific status for the following specimens:
Hyla chrysoscelis: Chase Co.: KU 203673; Chautauqua Co.: KU 203710; Cherokee Co.: KU 33490, 203665-68, 203706-07, 203720-22; Coffey Co.: KU 203705; Crawford Co.: KU 203718-19; Douglas Co.: KU 16371, 16373-381, 203995-96, 203991-92, 203993-94, 203676- 79, 203712-714; Elk Co.: KU 203711; Franklin Co.: KU 203669-671, 204038; Greenwood Co.: KU 203701; Jackson Co.: KU 203690-94; Jefferson Co.: KU 17398; Johnson Co.: KU 203723-24; Leavenworth Co.: KU 21145; Marshall Co.: KU 49182-84; Miami Co.: KU 203672, 204037; Montgomery Co.: KU 203708-09; Neosho Co.: KU 203715-17; Osage Co.: KU 17681, 203689; Pottawatomie Co.: KU 203674-75; Riley Co.: KU 203698-700; Shawnee Co.: KU 203688; Wabaunsee Co.: KU 203695-97; Wilson Co.: KU 203680-87; Woodson Co.: KU 203702-04
Hyla versicolor: Atchison Co.: KU 203740-41; Bourbon Co.: KU 28672; Cherokee Co.: KU 28671, 31099, 203746; Douglas Co.: KU 8122, 22013, 203745; Elk Co.: KU 203742-44; Franklin Co.: KU 203735; Greenwood Co.: KU 22931; Jefferson Co.: KU 203732-34; Miami Co.: KU 21833, 22112, 203736-39.
There is anecdotal evidence that the species complex range has been expanding in Kansas (Collins et al. 2010). Over the past 50 years, specimens have been found increasingly westward along riparian corridors where they weren't found previously.
(,   Museum Voucher) (,   Observation) (,   Literature Record) (,   iNat Record), (  Fossil)
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Full range depicted by light shaded red area. Export Google Earth (.kml)

• Occurrence Summary:  
• 2,969
  Records 
• 1,628
  Museum Vouchers 
• 1,341
  Other Observations 

Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):
Allen (22); Anderson (1); Atchison (28); Bourbon (20); Brown (31); Butler (50); Chase (33); Chautauqua (12); Cherokee (595); Clay (11); Cloud (2); Coffey (110); Cowley (17); Crawford (293); Dickinson (13); Doniphan (23); Douglas (352); Elk (8); Ellis (1); Ellsworth (1); Finney (1); Franklin (35); Geary (9); Greenwood (63); Harper (3); Harvey (1); Jackson (59); Jefferson (70); Johnson (82); Labette (41); Leavenworth (100); Linn (88); Lyon (10); Marshall (13); McPherson (1); Miami (74); Mitchell (1); Montgomery (60); Morris (9); Nemaha (16); Neosho (17); Osage (39); Ottawa (7); Pottawatomie (122); Pratt (1); Reno (1); Republic (2); Riley (93); Saline (10); Sedgwick (98); Shawnee (53); Sumner (26); Unknown (3); Wabaunsee (53); Washington (13); Wilson (28); Woodson (24); Wyandotte (20);

Fossil History:
Fossils from the Kanopolis Local Fauna of Ellsworth County (Pleistocene: Rancholabrean I) (Preston 1979, Holman 1972, Holman 1984; Holman 1995) are assignable to this taxon. Ellsworth County is outside the currently known range of this species.

Natural History:
According to Fitch (1958), in northeastern Kansas Gray Treefrogs inhabit the trees and low shrubs of woodland and woodland edge areas and are more arboreal than other frogs.
Their enlarged adhesive toe pads allow them to cling to smooth leaf surfaces. They appear to be very tolerant of high temperatures and frequently call from treetop perches on warm, humid summer nights. Fitch (l 956) further reported Gray Treefrogs to be active during the summer when humidity was high. He found specimens in small holes and niches in sun-heated limestone rocks, but the frogs maintained body temperatures lower than the rocks. During the summer, he observed these frogs on low-hanging branches in trees, perched in direct sunlight in no apparent discomfort, their bodies reaching temperatures as high as 90°F. In Osage County, Clarke (1958) observed activity in these treefrogs from 12 May to 28 July at an air temperature range of 60-88°F. Male Gray Treefrogs are territorial and maintain their territories by using encounter calls and fighting when another frog approaches too closely.
Gray Treefrogs normally breed from April to July. Caldwell and Glass (1976) reported choruses of these treefrogs from May to July at a small pond in Woodson County. Air temperatures of 60°F or above stimulated males to begin chorusing and to approach a suitable breeding site. Heinrich and Kaufman (1985) reported two males calling on 10 June on the Konza Prairie. Collins and Hillis (1985) and Hillis et al. (1987) recorded Kansas choruses of Hyla chrysoscelis from 11 April to 26 June, and of H. versicolor from 11 April to 22 June.
These amphibians breed in permanent, semi-permanent, or temporary pools with mud bottoms and weedy vegetation in or near woodlands. The male mounts a female in the water, clasping her behind her forelegs with his front limbs. A single female may lay from 700 to 3,800 eggs (Steven Roble, pers. com, 1980; Collins, 1993) in small floating masses. The eggs hatch in four or five days and the free-swimming tadpoles metamorphose within two months. The young frogs evidently remain on or near the ground within proximity of the breeding site during the first season following metamorphosis (Roble, 1979).
Collins and Hillis (1985) and Hillis et al. (1987) found few apparent differences in breeding site selection in Kansas between the two Gray Treefrogs; indeed, both species were taken at the same breeding site on the same date in Douglas, Elk, and Franklin counties. They noted, however, that Hyla versicolor was apparently restricted to breeding sites within heavily forested areas, whereas H. chrysoscelis used a wider variety of sites, whether forested or not. Breeding areas varied from temporary flooded ditches to rain pools in cultivated fields to permanent ponds and ranged in depth from 0.1-2.4 meters (few inches to eight feet). Only a few sites contained fish predators, and none was more than 152.4 meters (500 feet) from forest.
Recently, studies elsewhere have shown that when these two species bred at the same site, male H. chrysoscelis sat and called closer to the ground whereas H. versicolor chorused from more elevated perches; when allopatric at breeding localities, both species called from a wider range of elevations.
A specimen from Pottawatomie County contained a small cricket (Hartman 1906). These frogs eat both terrestrial and flying insects.

Occurrence Activity:
Number of Unique Obervations (=days): 212; Range: 17 Feb to 10 Nov

Chorusing:

Audio recording by Keith Coleman.

Chorusing Phenology: The black outlined dots denote the Julian date (day of the year; 1 January = 1 to 31 December = 365) an observation was made. The thin red line depicts the range of dates between the beginning of the first, and end of the fourth quartile (excluding outliers; Tukey method). The thick light blue bar represents the second and third quartile (interquartile range; the middle 50% of all observations). Only one observation per Julian date is included in the graphs; so a date with multiple observations carries the same weight as a date with only one observation. The vertical bars correspond to the 12 months of the year; January through December.
Number of Unique Obervations: 729; Range: 16 Mar to 23 Jul; Interquartile range: 29 Apr to 19 Jun;

Remarks:
First reported in Kansas by Cragin, (1880) based on a specimen from "Kansas" in the Cambridge Museum of Comparative Zoology. The earliest existing specimen (MVZ 43356) was collected in May of 1909 at Lawrence (Douglas County).
A complex of two separate, yet externally indistinguishable, species. For this reason, they are included in the same account, however, it should be noted that this arrangement should not minimize their recognition as independent evolutionary entities. Diploid Hyla chrysoscelis and tetraploid H. versicolor are cryptic species that range across much of eastern North America (Bogart, 1980; Powell, et al. 2016). The two species cannot be distinguished by morphology, but they have distinctly different calls (pulse rate at the same temperature) (Blair, 1958; Johnson, 1966; Gerhardt, 1974) that was noted prior to their recognition as different species (Wasserman, 1970; Bogart and Wasserman, 1972). They also differ in cell volume, nucleolar organizing regions (NOR's) (Keller, 2000), and as stated, karyotype. [Interestingly, Wasserman (1970) never correlated the trill rate with the karyotype. His study frogs (all considered H. versicolor) were from Alpine, New Jersey (in the range of what we currently consider H. versicolor, and just outside the range of H. chrysoscelis) and Bastrop, Texas (in the range of what we currently consider H. chrysoscelis, and just outside the range of H. versicolor). Later studies cite Wasserman (1970) as denoting that two chromosomal forms existed and associated them with the trill rate of their call, when in fact Wasserman never makes that connection. He states "It therefore appears likely that there are several tetraploid populations of this species [H. versicolor] or that the species in entirely tetraploid. It may be that the ploidy level and call type within this complex do not actually correlate.]
Tetraploid H. versicolor is the result of recurrent hybrid origins with a complex reticulate evolutionary history. H. versicolor is likely polyphyletic. Ptacek et al., (1994), analyzed mitochondrial sequences to infer that H. versicolor arose at least three times, twice from H. chrysoscelis and once from an unknown maternal ancestor.
Holloway et al. (2006), using mitochondrial and nuclear markers, suggested that H. versicolor arose multiple times from H. chrysoscelis and two other extinct lineages. They further report that parallel evolution of advertisement calls in tetraploid lineages has allowed these lineages to interbreed (exclusive of the diploid lineages), resulting in a single sexually interacting polyploid species (H. versicolor) despite the separate origins of polyploids from different diploids.
Tetraploid cells have approximately twice the volume of diploid cells and may be a mechanism for mate recognition among different tetraploid lineages. Keller and Gerhardt (2001) found that polyploidization (and the concomitant increased cell size) may lead to a predictable and consistent change in the advertisement call, which would result in automatic isolation of the tetraploids from the diploids but identification of other (even more distantly related) tetraploids as possible mates. Tucker and Gerhardt (2011) followed by demonstrating that artificially produced autotriploid females of the diploid species (Hyla chrysoscelis) show a shift in pulse rate preference in the direction of the pulse rate produced by males of the tetraploid species (Hyla versicolor). This process helps to explain why tetraploid lineages with different origins have similar advertisement calls and freely interbreed.
Rather than tetraploidy arising anew from diploid ancestors, the available mitochondrial data would also support the ‘triploid bridge hypothesis' (Ralin and Selander, 1979; Bogart and Bi, 2013) where new tetraploids arise from triploid hybrids. Furthermore, while these two species are often found in sympatry, the phylogenetic lineages within either of these species are generally allopatric, thus tetraploids are often sympatric with diploids that are not of the diploid lineage from which the tetraploids evolved.
Species in the complex are known to hybridize (Gerhardt et al., 1994) (male H. chrysoscelis X female H. versicolor).
Booker et al. (2022) determined that H. versicolor was most likely formed via autopolyploidization from a now extinct lineage of H. chrysoscelis. They uncovered evidence of significant hybridization between diploids and tetraploids where they co-occur, and demonstrated that historical hybridization between these groups led to the re-formation of distinct polyploid lineages following the initial whole-genome duplication event.
A histological examination of the type of H. chrysoscelis (Cope 1880) (ANSP 13672) demonstrated that the specimen was actually H. versicolor. In the interest of maintaining stability (at least 70 publications associating H. chrysoscelis with the diploid morphology at the time of publication) the authors chose not to elevate H. v. sandersi (Smith and Brown 1947) and instead petitioned the ICZN (Smith, Fitzgerald, and Guillette 1981) to designate a neotype (the holotype of H. v. sandersi; USNM 123978).
Duellman et al. (2016, Zootaxa 4104: 1–109) restricted Hyla to Eurasia and North Africa and referred the North American and East Asian sister taxon of this group to Dryophytes. This change has not received much of a following in US publications so far.
The species complex is freeze-tolerant and can produce cryoprotectants (glycerol and/or glucose) in response to lowering ambient temperatures (Schmid, 1982).
Their skin secretions can be very irritating to the eyes, so wash your hands after you handle them.
Based on a captive specimen , Snider and Bowler (1992) reported a maximum longevity for these frogs of seven years, nine months, and twenty days.