DO FEMALE COMMON FROGS CHOOSE THEIR BREEDING HABITAT TO AVOID PREDATION ON TADPOLES

Predation is an important mortality factor among larval amphibians. Fe male amphibians may therefore increase their fitness by choosing preda tor-free reproductive habitats. We studied whether female common frogs choose their breeding habitat in order to minimize tadpole mortality by fish predation. In a paired experimental design we manipulated twel ve freshwater rock-pools by introducing adult threespine sticklebacks in them and compared the numbers of reproducing female frogs and survi ving tadpoles with those in twelve unmanipulated pools at close distan ce. All pools had supported a breeding frog population during the two preceding years. Common frog females did not alter their pool choice a fter the fish introductions. There was no difference in the number of egg batches laid in manipulated and in control pools. The egg laying p attern did not differ qualitatively from that in the two previous year s. Laboratory experiments revealed that threespine sticklebacks prey h eavily upon young common frog tadpoles and field investigations indica ted significantly lowered tadpole survival in pools with sticklebacks. Thus, common frog females did not choose their reproductive habitat t o avoid predation on tadpoles. We discuss site tenacity and intraspeci fic competition among tadpoles as other possible agents affecting fema le reproductive habitat choice.