Populations of the brown frogs Rana arvalis, R. dalmatina and R. temporaria in 46 ponds in south Zealand during the years 1992-2020

For 29 consecutive years, the populations of three species of brown frogs, Rana arvalis, R. dalmatina and R. temporaria, were monitored in an open area (military training field) in South Zealand, Denmark. Population sizes were recorded by counting egg clumps. Not all egg clumps could be determined to species with full certainty. Some are designated “Likely R. temporaria”, and some are designated “Undetermined”. To obtain the most likely total number of R. temporaria egg clumps, figures for “Certain R. temporaria” and “Likely R. temporaria”  should be added. The tables show the number of egg clumps for each species in each of the waterbodies. Some waterbodies exist every year; others came into existence during the study period, and still others are temporary floodings existing only in a few years. In years when a given waterbody did not exist, the cell in the table is left blank. The waterbodies are numbered from 1 to 46 and their positions are shown on the map.
 The data allow analyses ..., The Excel sheets present data on the number of egg clumps of three species of brown frogs, in 46 water bodies, during the period 1992 to 2020 in a 1.8 km² area in Denmark The map shows the position of the 46 water bodies in the area Kulsbjerge in south Zealand. , , # Brown frog colonisations supplementary material

Data on the number of egg clumps of three species of brown frogs in 46 water bodies during the period 1992-2020.

## Description of the data and file structure

**Numerals** indicate the number of egg clumps.
**If a cell is empty**, it was not relevant to investigate the water body, e.g. if it did not exist yet, or did not exist in that year.
**(dry)** indicates that the water body was practically dry when investigated. This concerns cases when a water body holds water in most other years and so is believed to harbour an otherwise permanent population, which then has to move to another water body in that particular year.
**NI** means Not Investigated.
**0** means that the water body was investigated, but no eggs of that particular species were found.
**X** means the species was present and spawned, but the eggs were not counted.
**Water body** **numbers** refer to the map of the study area, with all 46 water bodies shown. Names of wat...