Livestock effects on reproduction of the Columbia spotted frog

We evaluated reproduction and recruitment of the Columbia spotted frog (Ran a luteiventris Thompson) in 70 ponds used by beef cattle and in 57 ponds no t used by beef cattle in northeastern Oregon. No significant differences we re detected in the number of egg masses or recently metamorphosed frogs in grazed and ungrazed sites. No pond characteristic measured could predict eg g mass numbers, but percent aquatic vegetation and dissolved oxygen had som e ability to predict recently metamorphosed frog numbers, Both variables ex plained 65% of the variability in recently metamorphosed frog numbers in gr azed ponds. At ungrazed ponds, 4 additional variables (presence of fish, el evation, percent of rock, and conductivity) were required to achieve the sa me level of variability in predicting recently transformed frog abundance. The egg mass volume was larger at grazed than at ungrazed ponds suggesting that grazed ponds may have a greater food abundance or larger (alder) indiv iduals.