Reproductive Behavior of Terrestrial Breeding Frogs Eleutherodactylus johnstonei in Guyana

Abstract

-I studied courtship, amplexus, and oviposition behavior of leaf litter and cavity breeding frogs (Eleutherodactylus johnstonei) in Georgetown, Guyana, using modified plastic planters equipped with observation windows. Both sexes used pots with and without plants as diumal retreats, but there was a preference for pots with plants. Calling males showed no preference for pots with or without plants. Females preferred pots with plants for oviposition. A gravid female initiated courtship by touching a calling male, who then led the female to one or more potential oviposition sites. The female either accepted or rejected cavities as nest sites, and sometimes abandoned the male if the nest cavities were unacceptable. Unacceptable cavities had direct contact with soil. Only 45% of the mating pairs employed axillary amplexus; males usually just sat on the females' backs. Twenty-five percent of the amplectic frogs then employed the reverse hind leg clasp after 0.50-1.75 h in the nest cavity. Oviposition lasted for 0.75-1 h, and approximately 14 externally fertilized, unpigmented eggs were laid in a pyramid. Fecundity was positively correlated with female size. The time from initial contact of the male by the female to egg laying was 4-6 h. Eggs hatched in approximately 13 d, and newly hatched froglets had snout-to-vent lengths of about 3.5 mm. Clutches were found during all months of the year; however, most clutches were deposited during the wettest months of the year. On average, males sired 3.3 clutches/year, while females produced 4.3 clutches/year. The most striking feature of E. johnstonei's reproductive behavior is that a few pairs used a reverse hind leg clasp during amplexus; a behavior only known for E. coqui that has internal fertilization. Much effort has been directed toward the documentation and description of the selective constraints of mating behavior in aquatic breeding anurans (Duellman and Trueb, 1986). Less effort has been expended on studying terrestrially breeding anurans (Duellman, 1989, 1992). Detailed life history information for terrestrial anurans is needed to test the generality of hypotheses based on studies of aquatic breeding species. We also need to better understand the diversity of the behavioral ecology of terrestrial anurans in the large genus Eleutherodactylus, because of many unusual characteristics already illustrated by only 1% of the species as follows: (1) they are not tied to standing water for reproduction, and have direct development (Crump, 1974, 1977; Lynch and Myers, 1983; Townsend and Stewart, 1986; Duellman and Trueb, 1986; Duellman, 1989, 1992); (2) there is a continuum from no parental care to either-sex parental care (Goin, 1947; Wells, 1981; Townsend, 1986; Duellman, 1992; G. R. Bourne, unpubl. data); (3) there is internal fertilization in at least two species (Wake, 1982); and (4) live-bearing is evident in one species (Wake, 1978). Unfortunately, the reproductive behavior of most terrestrial or arboreal breeding anurans whose eggs directly hatch into froglets (mode 17 sensu 'Present Address: Department of Biology, University of Missouri-St. Louis, St. Louis, Missouri 631214499, USA. E-mail: boume@ecology.umsl.edu Duellman and Trueb, 1986) are difficult to obser because many aspects of their behavior take place in sites hidden from human view. In the Neotropics, the largest genus of anurans, Eleutherodactylus, encompasses over 500 named species (Duellman, 1993) and is complete y terrestrial with direct development (Lynch and Myers, 1983; Frost, 1985; Duellman and Trueb, 1986; Duellman, 1992). Many of thes frogs are suitable for studies of their life histories if the problem of conducting continuous unobstructed observations can be overcome. To date, aspects of reproductive behavior of only a few Eleutherodactylus species have been detail d, for example, E. planirostris (Goin, 1947), E. diastema (Wilczynsky and Brenowitz, 1988), E. jasperi (Wake, 1978), E. cundalli (Diesel et al., 1995), and E. johnstonei (Bayley, 1950; Lemon, 1971; Beckwith, 1986; Ovaska 1991a, b, 1992; Ovaska and Hunt, 1992). However, details of courtship and mating behaviors have been published for E. coqui alone (Townsend et al., 1981; Narins and Hurley, 1982; Woolbright, 1985; Townsend, 1986, 1987, 1989; Townsend and Stewart, 1986, 1994; Stewart and Bishop, 1994), probably because they are not as secretive breeders as other species of Eleutherodactylus. Here I provide previously unknown details of the reproductive behavior of E. johnstonei, Barbour. Information is provided on: (1) a technique for unobstructed observation of courtship, mating, and egg laying behaviors of this leaf litter This content downloaded from 157.55.39.153 on Mon, 19 Sep 2016 04:56:36 UTC All use subject to http://about.jstor.org/terms