Determinants of Nesting Success in the Pumpkinseed (Lepomis gibbosus): A Comparison of Two Populations under Different Risks from Predation

Abstract

location, and water chemistry but with different fish communities. Ranger Lake had well-established populations of smallmouth and largemouth bass and few planktivorous fish, whereas Mouse Lake had no piscivores and many planktivorebenthivores capable of consuming pumpkinseed eggs and larvae. Both lakes had well-established pumpkinseed populations, but nesting success was significantly higher in Ranger Lake. The influences of environmental factors (nesting substratum and depth, temperature, solar radiation, precipitation, and wind velocity) on nesting success were investigated, and only wind-induced water turbulence was important. Although wind events were associated with significant amounts of nest destruction, the effects were the same in both lakes. Nest attacks and male nest defense were higher in Mouse Lake, particularly at night. These attacks came from the dense populations of golden shiners found at Mouse Lake and resulted in the loss of many pumpkinseed nests. We conclude that a predatorinduced cascade indirectly influenced nesting success. At Mouse Lake, piscivores were rare, planktivore-benthivore nest predators were abundant, nest-specific behavioral interactions were numerous and nesting success was low. At Ranger Lake, large piscivores were abundant, planktivore-benthivore numbers were low, and nesting success was high.