a female approaches, he leaps onto her back (Jacobson
1985). In territorial disputes, males of this species
often grapple with one another while hanging upside
down in the vegetation by their hind limbs; the loser
signals his defeat by dropping lower in the vegetation
or flattening himself against a leaf. In contrast to male
Fleischmann's Glass Frogs, which brood eggs imme-
diately after they are laid (see Sec. 5.5.3), male Emer-
ald Glass Frogs call while in amplexus and shortly
afterward.
Mating in Harlequin Frogs, which are also pro-
longed breeders, is poorly understood. Some pairs
stay in amplexus for at least 32 days. Prolonged am-
plexus may be a result of strong male-male competi-
tion due to a relative scarcity of receptive females
(Crump 1988). Because oviposition has not been ob-
served, the picture remains unclear. Perhaps males
whose territories contain the best oviposition sites
mate more times and stay in amplexus for shorter
periods than males with poorer territories and "tran-
sient" males, who do not hold territories.
Both male and female Harlequin Frogs are terri-
torial (Crump 1986, 1988). "Resident" frogs of both
sexes show strong site fidelity; they stay for as long
as two years within a small area (recapture radius of
a few meters) and usually return within a week if dis-
placed 10m upstream or down. Transient frogs wan-
der up and down the stream and show no homing
tendency. Male aggressive behavior, directed toward
other males, includes chasing, pouncing, squashing,
wrestling, and calling. Both territory holders and in-
truders emit a weak call, usually before engaging in
any physical contact, and the winner of a fight gives
the same call afterward. Males also produce "chirps"
during struggles with rival males and when unrecep-
tive females attempt to dislodge them from amplexus.
Aggressive behavior of females, which is directed
toward both males and other females, is like that of
males except for the absence of wrestling and calling.
Female aggression toward males seems to function in
the avoidance of prolonged amplexus. Females at-
tempt to dislodge males that clasp them prematurely.
They also chase them from their territories and may
leap onto their backs and pound their heads against
the substrate.
Of the two broad strategies—explosive and pro-
longed breeding—the former is associated with the
use of ephemeral pools (Wells 1977). Thus, explosive
breeders are often subject to the vagaries of these tem-
porary bodies of water. In 1987, for example, early
drying of pools caused high mortality of Golden Toad
embryos and larvae (Crump et al. 1992). Harding
(1993) interpreted this to mean that "water shortages
in temporary pools" had caused this species' decline,
and proposed management of pools as a solution to
the problem. Nevertheless, many prolonged breeders,
which do not depend on these ephemeral habitats,
declined along with the Golden Toad (e.g., Fleisch-
mann's and Emerald Glass Frogs, and the Harlequin
Frog; see Sec. 5.4.1). Drying of breeding pools due to
unusual weather cannot be a general explanation for
the declines (Pounds and Fogden 1996; see Sec. 5.4.3).5.5.3. Oviposition and Parental Care
in Frogs and Toads
Anurans are selective about where they lay eggs.
Golden Toads, for example, lay small clutches (157-
385 eggs) in ephemeral pools, mostly beneath the
stilt-like roots of elfin-forest trees (Jacobson and Van-
denberg 1991). Meadow Treefrogs deposit large
clutches (1800-2500 eggs), divided into masses of
several hundred each, in ponds of various sizes
(Crump 1991a). Females of the latter species appear
to avoid shallow sites that may dry up and pools with
conspecific tadpoles that may cannibalize eggs and
hatchlings (see Crump, "How Do Meadow Treefrogs
Decide," p. 173). Harlequin Frogs lay eggs in fast-
flowing streams, probably anchored to rocks; the tad-
poles have large ventral sucking discs that help them
maintain their position in the current (Starrett 1967,
McDiarmid 1971).
Parental care differs among species. Many rain
frogs (Eleutherodactylus) leave their eggs unattended,
often in leaf litter or bromeliads (Taylor 1955, Myers
1969, Scott 1983c), but some species tend their eggs.
A nest of the Tilaran Rain Frog containing 77 eggs was
buried in soil near a stream (Hayes 1985). For several
nights, the female sat on the nest and appeared to
defend it by pushing away intruding objects. Like-
wise, a female Leaf-breeding Rain Frog in Panama
laid eggs on the surface of a leaf and stayed closely
huddled to them until they hatched (Myers 1969).
Fleischmann's Glass Frog exhibits a similar brooding
behavior (Hayes 1991). At variable intervals, the male
presses his ventral side against the eggs to hydrate
them (mean clutch size = 26). Because the eggs are
shielded from rain on the undersurfaces of leaves,
desiccation causes high mortality of embryos not
brooded in this way. Keeping them too wet, however,
encourages parasitic fungi and drosophilid fly larvae,
which also cause high mortality. Males brood more
frequently under dry conditions. Brooding does not
guard directly against predation, but hydration thick-
ens the egg jelly, which discourages predaceous
arthropods (see Sec. 5.4.2). Brooding is essential im-
mediately after oviposition and is important during
early development; it becomes less crucial as devel-
opment advances. Male Emerald Glass Frogs do not
brood eggs (Jacobson 1985). The females brood for164 Amphibians and Reptiles