DOI: 10.5061/dryad.1g1jwsv3z
title: Populations of the brown frogs Rana arvalis, R. dalmatina and R. temporaria in 46 ponds in south Zealand during the years 1992-2020

description: 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 of changes in population size from year to year and shifts
 in the location of breeding populations. Analyses have been made of the
 time course of colonisation after a water body came into existence. 15
 initially unoccupied suitable ponds were available for colonisation by R.
 dalmatina after 1992. Permanent colonisation usually happened in the very
 first year that the waterbody existed. A total of 19 initially unoccupied
 suitable waterbodies could potentially be colonised by the two other
 species. Rana arvalis permanently colonised 17 ponds after an average of
 10.5 years. Rana temporaria permanently colonised eight ponds after an
 average of 13.4 years.  
description: 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 <br>The map shows the position
 of the 46 water bodies in the area Kulsbjerge in south Zealand. 
description: # 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 water bodies are
 the names used by the author. **”Colonisable from”** indicates the year of
 the first spring when the water body existed after it had been restored,
 or excavated, or formed during winter floodings. In the *R. dalmatina*
 data sheet, water bodies that were already inhabited by this species
 before the start of the study period have no year indicated under this
 heading.