Henry S. Fitch

“ Heavy rainfall is a necessity, not only to ensure a water supply in temporary pools where the frogs breed, but to create the moist conditions they require for an overland migration. An individual male may migrate to a pond and breed at least twice in the same season. Whether or not the females do likewise is unknown. Amplexus and spawning occur mainly within a day or two after the frogs reach the ponds. The males call chiefly at night, but there may be daytime choruses when breeding activity is at its peak. ”

“ The viscous dermal secretions copiously produced by a frog being handled made the animal so slippery that after a few seconds it might slide from the captor's grasp, and always was quick to escape when such an opportunity was presented. ”

“ Calling males were floating, almost upright, in the water within a few yards of shore, where there was dense vegetation. The throat pouch when fully expanded is several times as large as the entire head. When a person approached to within a few yards of frogs they usually stopped calling, submerged, and swam to a place of concealment.
Having heard the call of typical G. carolinensis in Louisiana, I have the impression that it is a little shorter, more sheeplike, and less insectlike than that of G. olivacea. The call of Gastrophryne is of such peculiar quality that it is difficult to describe. ”

“ De Carvalho (1954: 12) resurrected the generic name, Gastrophryne, for the American species formerly included in Microhyla, and presented seemingly valid morphological evidence for this plausible generic separation.
G. olivacea is obviously closely related to G. carolinensis; the differences are not greater than those to be expected between well marked subspecies. Nevertheless, in eastern Oklahoma and eastern Texas, where the ranges meet, the two kinds have been found to maintain their distinctness, differing in coloration, behavior, calls, and time of breeding. ”

“ Occasionally the ants attacked and killed small mammals caught in such traps. Among the thousands of kinds of insects occurring on the Reservation, this ant is one of the most numerous in individuals, one of the most important on the basis of biomass and provides an abundant food source for those predators that are ant eaters. Food supply probably is not a limiting factor to populations of Gastrophryne on the area. ”

“ The movements made by these frogs were of several distinct types:
1. Routine day to day movements from shelter to shelter within the area familiar to the animal, the "home range." 2. Shifts from one home range to another; such shifts may have been either long or short, and may have occurred abruptly or by gradual stages. 3. Travel by adults to or from a breeding pond. In most or all instances these adults were regularly established in permanent home ranges, and they often moved through areas unsuitable as habitat to reach the ponds. ”

“ Heavy precipitation, especially rains of two inches or more, stimulates the frogs to migrate in large numbers to breeding ponds. Even though there are several well spaced periods of unusually heavy rainfall in the course of a summer, each one initiates a new cycle of migration, mating and spawning. ”

“ The number of frogs caught from day to day under varying weather-conditions provided evidence as to the factors controlling surface activity. After nights of unusually heavy rainfall, a dozen frogs, or even several dozen, might be found in each of the more productive pitfalls. A few more might be caught on the following night, and occasional stragglers as long as the soil remained damp with heavy dew. Activity is greatest on hot summer nights. Below 20° C. there is little surface activity but individuals that had body temperatures as low as 16° C. have been found moving about. ”

“ Ant-eating frogs, a little less than twice natural size, adult and newly metamorphosed young, showing differences in size and coloration. The young is darker and has a leaflike middorsal mark which fades as growth proceeds.
The trend of growth after attainment of minimum adult size is also well shown by the records of marked individuals recaptured. Many of these were marked while they were still small so that their approximate ages are known. For those recaptured in their second year, after one hibernation, length averaged 30.92 mm. ”

“ At the pond on the Reservation I noted this same tendency many times. After a lull the chorus would begin with a few sporadic croaks, then four or five or even more frogs would be calling simultaneously from an area of a few square yards. Anderson (op. cit.: 34) found that in small groups of calling G. carolinensis there was a distinct tendency to maintain a definite pattern in the sequence of the calls. One "dominant" individual would initiate a series of calls, and others each in turn would take up the chorus.
Pairing takes place soon after the breeding aggregations are formed. ”

“ The flat pointed head seems to be in contact with the ground or very near to it as the animal moves about rapidly and erratically. The frog has a proclivity for squeezing into holes and cracks, or beneath objects on the ground. The burst of activity by one that is startled lasts for only a few seconds. ”

“ In G. olivacea in Kansas, time of breeding is controlled by the distribution of heavy rainfall creating favorable conditions. Onset of the breeding season may be hastened or delayed, or an entire year may be missed because of summer drought. If favorable heavy rains are well distributed throughout the summer, frogs of age classes that are not yet [Pg 289] sexually mature in the early part of the breeding season, may comprise the bulk of the breeding population in late summer. ”

“ The young grow a little more than one mm. in length per week. Those metamorphosed in early summer may attain minimum adult size before hibernation which begins in October. It seems that sexual maturity is most often attained in the second season, at an age of one to two years.
Gastrophryne belongs to a family that is primarily tropical in distribution, and frogs of this genus have much higher temperature thresholds than most other amphibians of northeastern Kansas, with a correspondingly short season of activity. ”

“ This shrew is common on the Reservation, especially in woodland. Many have been trapped in the pitfalls. On several occasions when a short-tailed shrew was caught in the same pitfall with ant-eating frogs, it was found to have killed and eaten them. Like the frogs, the shrews were most often caught in pitfalls just after heavy rains. Once in 1954 a shrew was found at the quarry in a pitfall that had been one of those most productive of frogs. ”

“ Most of these prey animals were represented by few individuals, and ants were much more numerous than any of the other groups. Anderson concluded that ants, termites, and small beetles were the principal foods. He noted that some of the beetles were of groups commonly found in ant colonies. Tanner reported that in a large number of the frogs which he collected in Douglas, Riley, Pottawatomie, and Geary counties, Kansas, the digestive tracts and feces contained only ants. ”

“ The pair was still joined, but the male was actually clasping only part of the time, and as the frogs moved about in the water, it became evident that they were adhering to each other by the areas of skin contact, which were glued together by their dermal secretion. They were unable to separate immediately, even when they struggled to do so. They [Pg 288] were observed for approximately 15 minutes before separation occurred, and during this time they were moving about actively. As they separated, the area of adhesion was discernible on the back of the female. ”

“ Less frequently, undisturbed individuals have been seen wandering on the soil surface. Such wandering occurs chiefly at night. Diurnal wandering may occur in relatively cool weather when night temperatures are too low for the frogs to be active. Wandering above ground is limited to times when the soil and vegetation are wet, mainly during heavy rains and immediately afterward. ”

“ 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. ”

“ The large average and maximum size in this sample of a breeding population may be typical after periods of drought years have prevented successful reproduction. Summer drought in 1952 and 1953 prevented breeding in those years, or, at least, it drastically reduced the numbers of young produced. One-year-old and two-year-old frogs may not have been represented at all in the sample of 58. Three-year-old frogs presumably made up a substantial part of the sample, since 1951 was a year of successful breeding. ”

“ Their account indicates that the dark dorsal mark present in young of olivacea but not present in adults, is better developed and longer persisting in other forms. Specimens of carolinensis, presumably adult, are figured which have the dark middorsal area contrasting with paler color of the sides. The dark area is seen to consist of dots or blotches of black pigment which may be in contact producing more or less continuous black areas, or may be separate and distinct producing a spotted pattern. Pigmentation is usually most intense along the lateral edges of the dorsal leaflike mark ”

“ For more than half the year, mid-October to early May the frogs are normally in hibernation. Body temperatures of active frogs ranged from 17.0° C. to 37.6° C., but more than two-thirds were within the relatively narrow range, 24.0° to 31°. Near the date of the first autumn frost the frogs disappear from the soil surface and from their usual shelters near the surface, presumably having retired into hibernation in deep holes and crevices. ”

“ In most individuals smaller than 20 mm., this dorsal mark is well defined and conspicuous. As growth proceeds, however, it becomes faint. In frogs 19 to 25 mm. long the marks have disappeared. In individuals of this size the brown ground color is markedly paler than in those newly metamorphosed, but is darker than in adults.
In large adults the dorsal coloration is a uniform pale tan, paler on the average in females than in males. ”

“ Males are more vagile. Of 21 adult males recaptured, none was less than 40 feet from its original location, whereas six of the 26 adult females were less than 40 feet away from the original point of capture. ”

“ The smallest one found was 19 mm. long (May 19, 1951) , and in each year except 1954 many such young were found that were less than 25 mm. in length in May or early June. None of the frogs marked at or near metamorphosing size has been recaptured, but the trend of early growth is well shown by Table 2 and Fig. 3. However, many juveniles that were captured and marked within a few weeks of metamorphosis were recaptured as adults. The selected individuals in Table 3 are considered typical of growth from "half-grown" to small adult size. Growth in many other individuals is shown in Figs. ”