SummaryBull, Evelyn L.; Carter, Bernie E. 1996. Tailed frogs: distribution, ecology, and association with timber harvest in northeastern Oregon. Res. Pap. PNW-RP-497. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 11 p.Tailed frogs (Ascaphus truer) were found in 42 of 80 streams surveyed in Union, Umatilla, Wallowa, and Baker Counties in 1992. At least three size classes of larvae were identified in seven of the streams, thereby suggesting that larvae transform after spending 3 or more years in the streams. The amount of cobble and fines in the streambed best predicted abundance of larvae, whereas, cobble, boulders, slope gradient, and stream buffers best predicted abundance of adults.Keywords: Amphibians, Ascaphus, northeastern Oregon, tailed frog, timber harvest.This study was designed to investigate the distribution, abundance, life history, and effect of timber harvest on tailed frogs. In 1992, 80 streams in northeastern Oregon were surveyed for tailed frogs. More intensive surveys (diurnal searches for larvae and nocturnal searches for adults) were conducted in 30 streams in 1993.Tailed frogs were found in streams in four counties (Union, Umatilla, Wallowa, and Baker Counties) in northeastern Oregon. Their presence in three of these counties was previously unknown.Tailed frog adults and larvae were present in streams all summer. It appeared that three or more age classes of larvae were present in most streams, thereby suggesting that larvae are in the streams at least 3 years before they transform into frogs. Transforming larvae were found in streams in July, August, and September; none was found in October. There were no significant differences in numbers of larvae or adults in streams with a low, moderate, or heavy amount of timber harvest; however, there was a general downward trend in the abundance of tailed frogs as the amount of timber harvest increased.It appeared that stream characteristics were more important than landscape characteristics in predicting the abundance of tailed frogs in streams. Stepwise regression selected the two-variable model by using the amount of cobble and fines in the streams as best able to predict larval abundance. For adult frogs, the best model was a four-variable model with the stream buffer, amount of boulders and cobble in the stream, and the slope gradient being the variables best able to predict the abundance of adult frogs.

No abstract

No abstract

Tailed frogs (Ascaphus truei) were found in 42 of 80 streams surveyed in Union, Umatilla, Wallowa, and Baker Counties in 1992. At least three size classes of larvae were identified in seven of the streams, thereby suggesting that larvae transform after spending 3 or more years in the streams. The amount of cobble and fines in the streambed best predicted abundance of larvae, whereas, cobble, boulders, slope gradient, and stream buffers best predicted abundance of adults. SummaryThis study was designed to investigate the distribution, abundance, life history, and effect of timber harvest on tailed frogs. In 1992, 80 streams in northeastern Oregon were surveyed for tailed frogs. More intensive surveys (diurnal searches for larvae and nocturnal searches for adults) were conducted in 30 streams in 1993.Tailed frogs were found in streams in four counties (Union, Umatilla, Wallowa, and Baker Counties) in northeastern Oregon. Their presence in three of these counties was previously unknown.Tailed frog adults and larvae were present in streams all summer. It appeared that three or more age classes of larvae were present in most streams, thereby suggesting that larvae are in the streams at least 3 years before they transform into frogs. Transforming larvae were found in streams in July, August, and September; none was found in October. There were no significant differences in numbers of larvae or adults in streams with a low, moderate, or heavy amount of timber harvest; however, there was a general downward trend in the abundance of tailed frogs as the amount of timber harvest increased. It appeared that stream characteristics were more important than landscape characteristics in predicting the abundance of tailed frogs in streams. Stepwise regression selected the two-variable model by using the amount of cobble and fines in the streams as best able to predict larval abundance. For adult frogs, the best model was a four-variable model with the stream buffer, amount of boulders and cobble in the stream, and the slope gradient being the variables best able to predict the abundance of adult frogs. 10 Appendix A 1 Appendix B