In many permanent ponds throughout western North America, the introduction
of a variety of exotic fish and bullfrogs (Rana catesbeiana) correlates wit
h declines in native amphibians. Direct effects of exotics are suspected to
be responsible for the rarity of some native amphibians and are one hypoth
esis to explain the prevalence of amphibian declines in western North Ameri
ca. However, the prediction that the permanent ponds occupied by exotics wo
uld be suitable for native amphibians if exotics were absent has not been t
ested. I used a series of enclosure experiments to test whether survival of
northern red-legged frog (Rana aurora aurora) and Pacific treefrog (Hyla r
egilla) larvae is equal in permanent and temporary ponds in the Puget Lowla
nds, Washington State, USA. I also examined the direct effects of bullfrog
larvae and sunfish. Survival of both species of native anuran larvae was ge
nerally lower in permanent ponds. Only one permanent pond out of six was an
exception to this pattern and exhibited increased larval survival rates in
the absence of direct effects by exotics. The presence of fish in enclosur
es reduced survival to near zero for both native species. An effect of bull
frog larvae on Pacific treefrog larval survival was not detected, but effec
ts on red-legged frog larvae were mixed. A hypothesis that food limitation
is responsible for the low survival of native larvae in some permanent pond
s was not supported. My results confirm that direct negative effects of exo
tic Vertebrates on native anurans occur but suggest that they may not be im
portant to broad distribution patterns. Instead, habitat gradients or indir
ect effects of exotics appear to play major roles. I found support for the
role of permanence as a structuring agent for pond communities in the Puget
Lowlands, but neither permanence nor exotic vertebrates fully explained th
e observed variability in larval anuran survival.