Spring migration rates and community structure of amphibians breeding in an old and newly established midfield ponds

Abstract

We studied the amphibian breeding migration into an old established (the beginning of the 1990s) pond and a new one (2007), using drift fences in 2008–2011. The two ponds were located at a distance of about 0.5 km from one another in a post-agricultural landscape in the Mazurian Lakeland, north-eastern Poland. We examined the community structure and migration rates of adults and juveniles. The amphibian breeding communities were similar in the two ponds in each year. The moor frog Rana arvalis was the most common species and comprised between 35 and 55 % of all adult amphibians migrating to both ponds. The new pond was colonized by adult amphibians in the first spring after its creation. In the second year, the amphibian migration rates doubled in the new pond and remained stable over the next two years. However, during the entire period of the study the old pond was a more attractive spawning site than the new pond, when measured by the number of migrating individuals of all recorded species. Despite some annual variation, there were no significant differences between the ponds in terms of the sex structure, mean body mass or migration timing of the predominant amphibian species. The most probable explanation for the observed differences in the rates of migration is breeding site fidelity.