CORTICOSTERONE AND ANDROGEN PLASMA-LEVELS IN MALE TOADS BUFO-BUFO DURING THE REPRODUCTIVE PERIOD

In the toad Bufo bufo reproductive activity took place within a few weeks in early spring: males were sexually active when entering and staying in the breeding pond and did not exibit any sexual behaviour when leaving. We analyzed changes in the plasma levels of corticosterone and androgens in the toad Bufo bufo during two consecutive breeding seasons under natural conditions. Males were trapped and blood collected at their arrival and departure from the pond where reproductive behaviour occurred. Androgens decreased in animals leaving the pond in both years and the final levers were negatively correlated with the length of stay in the water. The final levels of corticosterone were also negatively correlated to the time spent in the water. A significant corticosterone decrease in animals leaving the pond was observed only in the first year, and it is probably due to sampling technique.