TOPEKA, KANSAS
1956

25-7819

A FIELD STUDY OF THE KANSAS ANT-EATING FROG, GASTROPHRYNE OLIVACEA

By

Henry S. Fitch

INTRODUCTION

The ant-eating frog is one of the smallest species of vertebrates on the
University of Kansas Natural History Reservation, but individually it is
one of the most numerous. The species is important in the over-all
ecology; its biomass often exceeds that of larger species of
vertebrates. Because of secretive and subterranean habits, however, its
abundance and effects on community associates are largely obscured.

The Reservation, where my field study was made, is the most northeastern
section in Douglas County, Kansas, and is approximately 5-1/2 miles north
and 2-1/2 miles east of the University campus at Lawrence. The locality
represents one of the northernmost occurrences of the species, genus,
and family. The family Microhylidae is a large one, and most of its
representatives are specialized for a subterranean existence and a diet
of termites or ants. The many subfamilies of microhylids all have
distributions centering in the regions bordering the Indian Ocean, from
South Africa and Madagascar to the East Indies, New Guinea, and
Australia (Parker, 1934). Only one subfamily, the Microhylinae, is
represented in the New World, where it has some 17 genera (de Carvalho,
1954) nearly all of which are tropical. _G. olivacea_, extending north
into extreme southern Nebraska (Loomis, 1945: 211), ranges farther north
than any other American species. In the Old World only _Kaloula
borealis_ has a comparable northward distribution. Occurring in the
vicinity of Peiping (Pope, 1931: 587), it reaches approximately the same
latitude as does _Gastrophryne_ in Nebraska. The great majority of
microhylid genera and species are confined to the tropics.

Nearly all ant-eating frogs seen on the Reservation have been caught and
examined and individually marked. By November 1, 1954, 1215 individuals
had been recorded with a total of 1472 captures. In the summer of 1950,
Richard Freiburg studied this frog on the Reservation and his findings
(1951) led to a better understanding of its natural history. The
numbers of frogs studied by him however, were relatively small and the
field work was limited to the one summer. The data now at hand,
representing six consecutive years, 1949 through 1954, serve to
supplement those obt