EFFECTS OF LARVAL HISTORY AND MICROTAGS ON GROWTH AND SURVIVAL OF NATTERJACK (BUFO-CALAMITA) METAMORPHS

The metamorphic success of larval cohorts and the post-metamorphic gro wth of toadlets were studied in a large metapopulation of natterjack t oads (Bufo calamita) in the Rhinelands, Germany. Larval density was gr eater in the cohorts studied in 1991 than in those studied in 1992 and metamorphs were smaller in 1991 than in 1992, indicating short-term c arry-over effects. Metamorphic success and average snout-vent length w ere larger in the cohort originating from the early breeding period th an in those from the main breeding period in the previous year. The fu rther terrestrial development of three metamorph cohorts was followed until adulthood using commercial fish marks (microtags) for batch-tagg ing. Microtags are small pieces of wire which are injected below the s kin. Their presence is determined using a hand-wand metal detector. Th e short-and long-term effects of this new marking technique on growth and survival of almost 2000 free-ranging toadlets are reported. The re sults obtained indicate that microtagging is a useful and harmless tec hnique for the study of metamorphs.