According to Smith (1934: 503) stomachs of many specimens, from widely
scattered localities in Kansas, contained only large numbers of small
ants. Tanner (1950: 47) described the situation of a frog found on the
Reservation buried in loose soil beneath a flat rock, beside an ant
burrow, where, presumably, the frog could snap up the passing ants
without shifting its position. Anderson (_op. cit._: 21) examined
alimentary tracts of 203 specimens of _carolinensis_ from Louisiana,
representing a year round sample for several different habitats. He
found a variety of small animals including ants, termites, beetles,
springtails, bugs, ear-wigs, lepidopterans, spiders, mites, centipedes,
and snails. 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. Wood (1948: 226) reported an individual of _G. carolinensis_ in
Tennessee found under a flat rock in the center of an ant nest.
Freiburg (_op. cit._: 383) reported on the stomach contents of 52
ant-eating frogs collected near the Reservation. Ants constituted nearly
all these stomach contents, though remains of a few small beetles were
found. The ants eaten were of two kinds, _Lasius interjectus_ and
_Crematogaster_ sp. The latter was by far the more numerous.
Although I made no further study of stomach contents, the myrmecophagous
habits of _Gastrophryne_ have come to my attention frequently in the
course of routine field work. Individuals kept in confinement for a day
or more almost invariably voided feces which consisted mainly or
entirely of ant remains, chiefly the heads, as these are most resistant
to digestion.
Often upon examining frogs I have found ants (_Crematogaster_ sp.) or
their severed heads, attached with mandibles embedded in the skin. To
have been attacked by ants, the frogs must have been in or beside the
ants' burrow systems. Frequently the frogs that were uncovered beneath
rocks were adjacent to clusters of ants or to their nests or travelways,
in a position strategically located to feed upon them, as described by
Tanner. Often the feces of the frogs were found in pitfalls or under
flat rocks. Although these feces were not analyzed, they seemed to
consist mainly or entirely of ant remains.
The species of _Crematogaster_, which is the chief food of
_Gastrophryne_ in this region, is largely subterranean in habits, and is
extremely abundant. Any flat rock in damp soil is likely to harbor a
colony beneath it. Colonies are situated also in damp soil away from
rocks, beneath almost any kind of debris, and in hollow weed stalks and
decaying wood. Live-traps for small mammals, having nest boxes attached,
almost always were occupied by colonies of _Crematogaster_, if they were
left in the field in warm, humid weather. 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.