In this amphibian monitoring programme, around 1500 spawning areas with known or potential amphibian populations are monitored throughout the canton. Amphibian experts visit a random sample of over 300 spawning areas each year and systematically document the species occurring and the condition of the water bodies. This annual sample is a mixture of comprehensive mapping of certain sub-areas (5-year cycle), a canton-wide random sample and some water bodies that are surveyed annually to monitor their success.

Abb2 Stichprobe

The Landscape and Waters Department of the Canton of Aargau has commissioned Hintermann & Weber AG with the coordination of this extensive monitoring, i.e. we determine the annual sample, request the volunteer field workers and provide them with both technical and organisational support during the field season. We monitor the return of the data and are the interface for data entry by info fauna karch. The data collected is processed and used to calculate key figures on the development of amphibian populations. Further information can be found at this link (here). We also organise regular amphibian identification courses on behalf of the naturama Aargau nature museum. These make an important contribution to maintaining the pool of volunteers for monitoring.

The extensive dataset of more than 25,000 species records since 1999 serves the cantonal specialist centre as a basis for its day-to-day work, such as the planning of enhancement/promotion measures including subsequent impact monitoring or the assessment of the consequences of construction projects, etc. The data is also used for scientific evaluations. The data is also used for scientific analyses. For example, a newly developed statistical model was used to investigate the effect of water frog competition on the local population sizes of natterjack toads, yellow-bellied toads and midwife toads. The latter two actually showed significantly lower population densities when water frogs were also present in the same watercourse (Roth et al. 2016 and Bühler et al. 2017).

Abb4 1171 GBU INSIDE

A metapopulation analysis using the Aargau data set showed that populations increased primarily in areas where an above-average number of new water bodies were created (Moor et al. 2022). More in-depth analyses showed that both the characteristics of the new water bodies and their spatial location are decisive for colonisation by target species. The probability of recolonisation increased with increasing total water area of a spawning site for all target species except the yellow-bellied toad. For natterjack toads, yellow-bellied toads, crested newts and great crested newts, a fluctuating water level, i.e. occasional drying out of the water body, was also an important factor. And for all target species, the distance at which the species was already present was decisive for recolonisation (Moor et al. 2024). Thanks to such analyses, concrete recommendations for nature conservation practice can be derived.


The following publications were produced using the data set from the Aargau amphibian monitoring programme (selection):

  • Roth T., Bühler C., Amrhein V. (2016): Estimating Effects of Species Interactions on Populations of Endangered Species. The American Naturalist, 187(4), 457-467.
  • Bühler C., Roth T., Amrhein V. (2017): Verdrängen Seefrosch und Teichfrosch gefährdete Amphibienarten? KBNL Inside 2017/3
  • Moor H., Bergamini A., Vorburger C., Holderegger R., Bühler C., Egger S., Schmidt B. R. (2022). Bending the curve: Simple but massive conservation action leads to landscape-scale recovery of amphibians. Proceedings of the National Academy of Sciences, 119(42), e2123070119.
  • Moor H., Bergamini A., Vorburger C., Holderegger R., Bühler C., Bircher N., & Schmidt B. R. (2024). Building pondscapes for amphibian metapopulations. Conservation Biology, e14165.