frogs: Counts of the number of frogs in a water body
Description
Counts of the number of frogs in ponds of the Canton Aargau, Switzerland.source
The data is provided by Isabelle Floess, Landschaft und Gewaesser, Kanton Aargau.Details
The amphibian monitoring program started in 1999 and is mainly aimed to survey
population trends of endangered amphibian species. Every year, about 30 water
bodies in two or three randomly selected priority areas (out of ten priority
areas of high amphibian diversity) are surveyed. Additionally, a random selection
of water bodies that potentially are suitable for one of the endangered amphibian
species but that do not belong to the priority areas were surveyed. Each water body
is surveyed by single trained volunteer during two nocturnal visits per year.
Volunteers recorded anurans by walking along the waters edge with precise rules
for the duration of a survey taking account of the size of the surveyed water
body and noting visual encounters and calls. As fare as possible, encountered
individuals of the Pelophylax-complex were identified as Marsh Frog (Pelophylax
ridibundus), Pool Frog (P. lessonaea) or hybrids (P. esculentus) based on
morphological characteristics or based on their calls. In the given data set,
however, these three taxa are lumped together.References
Schmidt, B. R., 2005: Monitoring the distribution of pond-breeding amphibians,
when species are detected imperfectly. - Aquatic conservation: marine and freshwater
ecosystems 15: 681-692.Tanadini, L. G.; Schmidt, B. R., 2011: Population size influences amphibian
detection probability: implications for biodiversity monitoring programs. - Plos One 6: e28244.