CREATING A POND ARRAY TO TEST THE EFFECTS OF PREDATION BY LARVAL NEWTS ON THE EGGS OF CALIFORNIA RED-LEGGED FROGS
|Michael F Westphal; United States Bureau of Land Management; email@example.com; Karen Kiemnec-Tyburzcy
Ecological interactions whose effects have conservation significance are often difficult to test in the wild. A potential negative predatory interaction between larval roughskinned newts, Taricha granulosa, and California red-legged frogs, Rana draytonii, was recently observed in a coastal pond in Santa Cruz County, California. In order to explore the effect of larval newts on R. draytonii, we constructed 9 small ponds where factorial experiments can be conducted in a setting where confounding factors can be controlled. The ponds are approximately 6 meters in diameter and one meter deep and are arranged in a triangular array to create three sets of three ponds, each of which is approximately 6 meters apart from center to center. Ponds will be ringed with 18 inch aluminum flashing to control ingress into the ponds and the array will be fenced to exclude cattle and pigs. Preliminary experiments will include rearing R. draytonii from salvaged egg masses to assess background reproductive success in the absence of predators. Subsequent experiments will include factorial treatments where newt larva will be combined with R. draytonii eggs, and eggs-only ponds and larva-only ponds will constitute the controls. The results will guide ongoing management of natural populations where R. draytonii and T. granulosa are sympatric.