1996). The reports, however, have met with some skep-
ticism. Because extreme natural fluctuations could be
mistaken for a more significant phenomenon (Pech-
mann et al. 1991), researchers have been divided over
how to interpret the observed patterns (see Pounds,
"Monteverde Salamanders," p. 172). The Golden Toad
has thus figured prominently in one of the most vola-
tile debates in conservation biology, and Monteverde
has provided an important test case (Blaustein 1994,
Pechmann and Wilbur 1994, Blaustein et al. 1994a,
Sarkar 1996, Pounds et al. 1997). The debate has hinged
on standards of scientific proof and the scarcity of long-
term data needed to judge whether a population is in
decline. Diverse tropical faunas, however, afford an
approach that does not rely on these data. A compari-
son of the number of disappearances at Monteverde to
the number that could be expected for an assemblage
of demographically unstable populations suggests that
the declines go beyond natural fluctuations (Pounds
etal. 1997).
It is essential that we identify the causes and ex-
plore the implications of these patterns. We could
develop a plausible model of how the ecological con-
text has changed if we had sufficient data—from both
the past and the present—on levels of resources, in-
teractions with competitors, predators, and parasites
and the influences of physical and chemical condi-
tions of the environment. The picture, however, is
woefully incomplete. Moreover, some of the poten-
tially most instructive data cannot be obtained be-
cause the populations no longer exist. We must there-
fore rely on the available information on ecology to
provide clues that point the way to future research.
The present chapter summarizes this information for
Monteverde's amphibians and reptiles. Although pre-
vious discussion of the declines and disappearances
has focused on frogs, toads, and salamanders, I dem-
onstrate that lizards and snakes have also been af-
fected. I provide an overview of the patterns, ask what
bearing they may have on our understanding of the
declines, and suggest topics for further study.
5.1. The Area and Its FaunaI focus on amphibians and reptiles in a broad east-west
belt that bisects the Cordillera de Tilaran (Fig. 1.5).
This belt extends from the 690-m contour in the drain-
ages of the Rios Lagarto and Guacimal on the Pacific
slope, to 1850 m along the continental divide, and to
600 m in the Pefias Blancas valley on the Caribbean
slope, following Hayes et al. (1989). Many biologists
have contributed to our knowledge of Monteverde's
herpetofauna. The first species list (Van Devender
1980) built on the work of Jay Savage and his associ-ates (Savage and Villa 1986, Villa et al. 1988). Subse-
quent lists (Timmerman and Hayes 1981, Hayes et al.
1989) amplified the study area and added species
descriptions, annotations on distribution and natural
history, and identification keys. A revised checklist
(Appendix 8) includes 161 species, seven of which
are additions. The 60 amphibian species include 2
caecilians (elongate limbless animals), 5 salamanders,
and 53 anurans (frogs and toads). The 101 reptile spe-
cies include 29 lizards and 71 snakes. To standard-
ize nomenclature, I follow a 1995 revision of the Costa
Rican checklist plus recent changes (J. Savage, un-
publ. data). Common names are from Hayes et al.
(1989) with some modifications; hereafter I use these
rather than the scientific names, which are in Appen-
dix 8. The numbered zones used to describe distribu-
tion (Zones 1-6; Appendix 8) also follow Hayes et al.
(1989), with one exception: Zone 5 extends down to
a point just above the junction of the Pefias Blancas
trail and the Rio Pefias Blancas (950 m).
Although species composition is well known at
Monteverde compared to most tropical localities, the
checklist is probably incomplete. Some secretive spe-
cies—especially snakes, which often occur at low den-
sities in the tropics (Henderson and Hoevers 1977)—
are likely to be added for the areas farthest from the
Monteverde community (Hayes et al. 1989). Turtles
could inhabit the lower elevations (Zones 1 and 6) but
are unknown in the region except for an unconfirmed
sighting of Kinosternon scorpiodes on the Pacific
slope. Estimates of diversity (a term I use interchange-
ably with "species richness" to refer to the number of
species) are conservative, because of incomplete sam-
pling, and uncertainties with taxonomy. For example,
preliminary data suggest that further study of rain
frogs (Eleutherodactylus, a large genus rich in species
that closely resemble one another; Savage 1975) could
reveal the presence of additional representatives.5.1.1. Recent Changes in the Fauna
Amphibians. Although early studies of disappear-
ances in the Monteverde region focused on the Golden
Toad and the Harlequin Frog (Crump et al. 1992,
Pounds and Crump 1994; Fig. 5.3), other anuran spe-
cies have disappeared. To assess the number of dis-
appearances, my co-workers and I surveyed popula-
tions in a 15-km east-west belt that averages 2 km in
width (Pounds et al. 1997). This belt corresponds to
a core area where most earlier sampling had been
done and includes habitats in each of the area's cli-
matic and vegetation zones (see Chap. 2, Physical En-
vironment). Before 1987, it contained populations of
all anuran species on the Monteverde checklist, al-
though some species were rarely encountered (Hayes151 Amphibians and Reptiles