HABITAT

In the northeastern part of Kansas at least, rocky slopes in open woods seem to provide optimum habitat conditions. This type of habitat has been described by several earlier workers in this same area, Dice (1923: 46), Smith (1934: 503) and Freiburg (1951: 375). Smith (1950: 113) stated that in Kansas this frog is found in wooded areas, and that rocks are the usual cover, but he mentioned that outside of Kansas it is often found in mesquite flats that are devoid of rocks. Freiburg's field work was done almost entirely on the Reservation and was concentrated in "Skink Woods" and vicinity, where much of my own field work, both before and afterward, was concentrated. On the Reservation and in nearby counties of Kansas, the habitat preferences of the ant-eating frog and the five-lined skink largely coincide. In an account of the five-lined skink on the Reservation, I have described several study areas in some detail (Fitch, 1954: 37-41). It was on these same study areas (Quarry, Skink Woods, Rat Woods) that most of the frogs were obtained.

Although G. olivacea thrives in an open-woodland habitat in this part of its range, it seems to be essentially a grassland species, and it occurs throughout approximately the southern half of the Great Plains region. Bragg (1943: 76) emphasized that in Oklahoma it is widely distributed over the state, occupying a variety of habitats, with little ecological restriction. Bragg noted, however, that the species is rarely, if ever, found on extensive river flood plains. On various occasions I have heard Gastrophryne choruses in a slough two miles south of the Reservation. This slough is in the Kaw River flood plain and is two miles from the bluffs where the habitat of rocky wooded slopes begins that has been considered typical of the species in northeastern Kansas. It seems that the frogs using this slough are not drawn from the populations living on the bluffs as Mud Creek, a Kaw River tributary, intervenes. The creek channel at times of heavy rainfall, carries a torrent of swirling water which might present a barrier to migrating frogs as they are not strong swimmers. The frogs could easily find suitable breeding places much nearer to the bluffs. Those using the slough are almost certainly permanent inhabitants of the river flood plain. The area in the neighborhood of the slough, where the frogs probably live, include fields of alfalfa and other cultivated crops, weedy fallow fields, and the marshy margins of the slough. In these situations burrows of rodents, notably those of the pocket gopher (Geomys bursarius), would provide subterranean shelter for the frogs, which are not efficient diggers.

The frogs may live in many situations such as this where they have been overlooked. In the absence of flat rocks providing hiding places at the soil surface, the frogs would rarely be found by a collector. The volume and carrying quality of the voice are much less than in other common anurans. Large breeding choruses might be overlooked unless the observer happened to come within a few yards of them. Most of the recorded habitats and localities of occurrence may be those where the frog happens to be most in evidence to human observers, rather than those that are limiting to it or even typical of it.

On September 20, 1954, after heavy rains, juveniles dispersing from breeding ponds were in a wide variety of situations, including most of the habitat types represented on the Reservation. Along a small dry gully in an eroded field formerly cultivated, and reverted to tall grass prairie (big bluestem, little bluestem, switch grass, Indian grass), the frogs were numerous. Many of them were flushed by my footsteps from cracks in the soil along the gully banks. In reaching this area the frogs had moved up a wooded slope from the pond, crossed the limestone outcrop area at the hilltop edge, and wandered away from the woods and rocks, out into the prairie habitat. In this prairie habitat there were no rocks providing hiding places at the soil surface, but burrows of the vole (Microtus ochrogaster) and other small rodents provided an abundance of subterranean shelter. In the summer of 1955 the frogs were seen frequently in this same area, especially when the soil was wet from recent rain. When the surface of the soil was dry, none could be found and presumably all stayed in deep cracks and burrows.

Anderson (1954: 17) indicated that G. carolinensis in Louisiana likewise occurs in diverse habitats, being sufficiently adaptable to satisfy its basic requirements in various ways.