Kovács, T. and J. Török 1995. Dietary responses by Edible Frog (Rana esculenta complex) to wetland habitat change in Hungary. Proceedings of Workshop 2 of the International Conference on Wetlands and Development, Kuala Lumpur, Malaysia, 9-13 October 1995, 79-86.

Abstract -- The study was conducted in a protected wetland area in Western Hungary. Since 1985, a long- term, 2-part research programme has been conducted in the area: in an old marshland and in a large, artificial water reservoir which began operating in 1985. In this project, the feeding ecology of amphibian species was studied. Changes in the food composition of Edible Frog (Rana esculenta complex) was observed to change over a 9-year period. This frog is known as a generalist and opportunistic forager, and its diet may reflect changes in the invertebrate biodiversity of its habitat. Food samples were collected in 1985-86, 1988-89 and 1992-93 by stomach flush method. In the first sampling period, the diet of frogs was less diverse in the reservoir than in the old marshland. At this time, the vegetation of the reservoir consisted of pioneer and planted communities (reed beds and willow and poplar saplings), and the food supply was rather poor and ephemeral. Over nine years, the extent of reed beds increased and typical lacustrine communities spread over the area. In the last two sampling periods the diet diversity was similar in the two areas: diet diversity did not change in the marshland, whereas in the reservoir the frogs diet became more diverse over time. In the reservoir, the dominant food type during the first sampling period was dipterans (mainly chironomids), however as the wetland vegetation evolved the dipteran content decreased and spiders, beetles, heteropterans and snails gradually appeared in the diet.