In low-productivity, high-altitude habitats food can become a limiting factor for the occurring amphibians. Common frog eggs deposited in ponds and the developing tadpoles represent energy-rich prey for syntopic Alpine newts that should be advantageous for storing sufficient amounts of energy to survive hibernation and breed the following spring. In our study population in the Zillertal Alps, Austria at 2100 m a.s.l., in two consecutive years we found the body mass of Alpine newts to be significantly higher in ponds containing tadpoles of the common frog than in ponds without tadpoles. As the frogs forage mostly on land, we regard their eggs as an allochtonous nutrient subsidy for ultra-oligotrophic high-altitude ponds that may have a profound effect on the fitness and distribution of Alpine newts and common frogs.