Räuber & Beute

Räuber & Beute
Räuber & Beute
Räuber & Beute
A software to calculate, display and manipulate predator prey population dynamics. The program supports English (default) or German.

This software is for educational purpose and suitable for school and lower university classes.

Don't hesitate to contact me for further information!

Ein Programm zum Berechnen, Anzeigen und Manipulieren der Populationsdynamik in einem einfachen Räuber-Beute-System. Die Programmoberfläche unterstützt englisch (Standard) und deutsch. Nicht alle Teile der Anleitung sind auf deutsch verfügbar.

Diese Software ist für Lehrzwecke gedacht und geeignet für Schul- und untere Universitätsklassen.

Bei Rückfragen, Anregungen, Wünschen einfach das Kontaktformular nutzen!


Table of Content - Inhaltsverzeichnis

Welcome - a brief introduction about the program

License - terms of use

Requirements - what is needed to run this program?

Installation - installation of the program

Usage - how to use the programm

Download - get your copy here

FAQ - frequently asked questions

History - history and future develoment

Welcome - Willkommen

Räuber & Beute is a software that computes and displays the predator prey population relation. The core of the program is based on the Lotka-Volterra algorithm. But it is also enhanced with a few environement parameters.
The dynamics are calculated for a given habitate which is in lose contact to neighbor habitates (a limited migration is possible). The simulation is assuming simplified years. Prey can breed once or twice a year, predators once. Lethality is higher during winter. Winters can be normal or tough ("icewinter"). Also a simplified virus epedemia (prey or predator) can get elicited manually. The virus infection dynamics is based heavily on popuation density, but there are also a few random parameters (lethality). Usually the virus infection follows a bell shaped course.
Many parameters can be manipulated in real time (see usage). As of yet the program language is English or German with English being the default language.

The program is probably of educational and/or scientific interest only.

Räuber & Beute ist ein Programm zum Berechnen, Anzeigen und Manipulieren der Populationsdynamik in einem einfachen Räuber-Beute-System. Grundlage des Programms ist der Lotka-Volterra-Algorithmus. Es ist darüberhinaus mit ein paar Umweltparametern erweitert.
Die Dynamik wird für ein gegebenes Habitat berechent, das in lockerem Kontakt zu Nachbarhabitaten steht, so dass eine begrenzte Migration möglich ist. Die Simulation legt ein vereinfachtes Jahr zu Grunde. Beutetiere können sich einmal oder zweimal pro Jahr fortpflanzen, Räuber einmal. Die Sterblichkeit ist im Winter höher als im Sommer, Winter können normal oder streng sein ("Eiswinter"). desweiteren können einfache Virusepedemien (Räuber oder Beute) manuell ausgelöst werden. Der Verlauf der Virusepedemie basiert,ergänzt um einige Zufallsparameter (Lethalithät des Virus), stark auf der Populationsdichte. Der Verlauf der Infektionsrate ist meist glockenförmig.
Viele Parameter der Simulation können in Echtzeit verändert werden, Daten können als Grafikdatei abgespeichert werden. Das Programm unterstützt Deutsch und Englisch als Sprache, wobei Englisch die Standardsprache auf allen nicht deutschsprachigen Systemen ist.

Das Programm ist wahrscheinlich nur von didaktischem und/oder wissenschaftlichen Interesse.

License - Lizenzbestimmung

This software is free for personal use. You may use it on your own risk. You are free to copy and distribute the archive. When distributing and/or spreading the program you must not:

  • charge money
  • modify the archive.
  • Note: If you want to use this software for teaching purposes in lectures, classes or courses (for schools, universities or other educational institutions) it is mandatory to obtain a permission from the author - please contact me.
    I am happy for any feedback though.

    Dieses Programm ist frei zur privaten Nutzung. Nutzung auf eigene Gefahr. Es ist erlaubt das Archiv zu kopieren oder zu verteilen. Wenn es angeboten oder verteilt wird darf nicht:

  • Geld verlangt werden
  • das Archiv irgendwie verändert werden.
  • Anmerkung: Falls das Programm zu Lehrzwecken in Klassen, Kursen, Vorlesungen oder ähnlichem eingesetzt werden soll, ist es notwendig die Erlaubnis vom Autor dafür einzuholen. Bitte mich kontaktieren.


    This software is written in the language Hollywood and hence available for many systems, either as native application or as .hwa-applet code. There is no additional software required and it should run on any computer running one of the supported operating systems. Be sure, you have downloaded the program version for your particular operating system. You may need a processor better not less than 400 MHz and a few MB of available RAM as well as a screen resolution of at least 1024*600 pixels and minimum 16 bit colour depth.


    Once you've downloaded the archive, unpack it and copy it to any destination you like (target drive needs at least 2.3 MB free space). You may put it on your harddsik, on a usb key or even on a server. There is no special installation process required.


    Just doubleclick the program icon. Once the splash screen has vanished the program starts with three windows: the control panel (shown below), the running average data of a 1 year period and the actual "real time" population dynamics.

    The program starts in a halted mode. To run the actual simulation you need to click on the Pause button within the control panel. Just play around with the buttons and sliders to change parameters of the prey predator dynamics.


  • Restart: reset all parameters and start over again.
  • Pause: halt the program
  • 2nd litter: Two prey generations per year (insted of only one)
  • Virus Pred.:A virus outbreak for predators (some good share will die)
  • Virus Prey: A virus outbreak for the prey (some good share will die)
  • Icewinter: An extreme winter that stresses the prey quite more than a normal winter

  • save current data as .png: save current data of the population dynamics and running average as .png files.
  • Wechseln zu deutsch: Change language to German (or back to English)

  • hide RA Fenster: hide (if hidden: show) the window that displays the running average data
  • hide PD Fenster: hide (if hidden: show) the window that displays the real time populaton dynamics

  • Sliders
  • Repro rate prey:Manipulate reproduction rate of the prey
  • Repro rate predator:Manipulate reproduction rate of the predators
  • Lethality prey:manipulate natural lethality factor of the prey
  • Lethality predator:manipulate natural lethality factor of the predators
  • Below the sliders the actual value is displayd in x.xx digits.

    At the bottom of the control panel window the current population of prey is continuously given as actual number as well as the population of predators.
    Below the "save current data as .png" the number of the last saved file is given. The files are saved to a directory called "RB-files" which is automatically generated at the actual directory the binary resides in. Each click on the save button will save two files: one for the running average (the file names follow this scheme: RAv_currentdate_currentnumber.png). and one for the population dynamics (the file names are following this scheme: RTime_current date_currentnumber.png). The RT .png-file has the last prey/predator numbers written to the bottom of the picture. On startup the program detects whether files of the current date are existing already and - if files exist - does apply the actual next number to the file name.

    There are two graphs displaying the population of the predators (blue) and prey (green) over time. One as a detailed actual population monitor ("real time" population numbers). This is shown at the larger graph window (titled "Population dynamics - Real Time" and may look like shown below.

    The vertical resolution (number of individuals) is not identical for prey and predators. The distance between two horizontal lines is 400 for prey and 10 for predators. Each 2nd thin vertical line (dark grey) denotes the beginning of a virtual year (drawing eastate is sufficient for 8 years), the horizontal thick lines at the top area denote the virtual winter time. White indicates a normal winter, black an "Icewinter" (stronger winter). Thin vertical lines denote a virus outbreak. A virus infectious for prey is marked by a red line, for predators the line is purple. Additionally at the bottom of the window the infection rate is given. Infection rate and course depends on several parameters, most important the size of the population. Once the drawing estate is filled for the first time all data gets continuously overwritten by new data. Right sided to the redly tinted cursor there's old data and leftly behind that cursor new data appears.

    The example screen shot shown here demonstrates many of the properties: There is an "Icewinter" (indicated by the thick black horizontal line), a rather small virus outbreak (indicated by the thin purple horizontal line) is affecting the predator population. Also, indicated by the thin red horizontal line, a virus outbreak lethally for prey is shown. The example shown demonstrates the interrelation of a prey virus and the predator population nicely.

    The 2nd graph shows a running average of the predator prey population for a continuous year period (365 days) year and may look like this:

    Again, green denotes the prey population and blue the predator population. Each 2nd thin vertical line (dark grey) denotes a year, the window hence has a drawing space for about 38 years. It is a continuous plot. The vertical resolution is of the same ratio as at the population dynamice window for prey while each horizontal line distance equals to 6 predator individuals here. At top of the plot thin horizontal lines indicate average times when a virus was affecting the population.

    The running average is good for long time observations and shows the Lotka-Volterra properties quite nicely (lagging maxima and minima time positions between prey and predator population).


    Grab a copy for your particular system from here:

    V1.4 - Download (Windows version)
    V1.4 - Download (MorphOS version)
    V1.4 - Download (Amiga 68k version)

    Or get the universal .hwa applet code for the Hollywood player which is available for Android, Windows, OS X, Linux, MorphOS, Amiga and AROS:

    V1.4 - Download (Hollywood player applet)

    Except for Windows the archives are packed with lha. That's a common packer on MorphOS (my development system) and AmigaOS. Most systems should have no problem to decrunch the archive - at least Winzip® >V11.1 is able to decrunch it.

    Note: You must not change the archive!

    Versions for Linux (x86, ARM or ppc), OS X (x86 or ppc), AROS (x86) and OS4 (ppc) are yet available on request only. Please mail for a copy.


    On the running average window the very first two data points (one for for prey and one for predator) seem a bit strange Well, that's a minor flaw I was too lazy yet to cover. Maybe next release...

    I don't like dictatorship and want to save my data elsewhere than the program forces me...? As of yet there's no way to change saving location. Will get changed with a next version.

    I found a bug, want to discuss the data or algorithm, have a feature request or want to donate you a bag of gold ducates? Well, in that case don't hesitate to contact me.

    Windows says this program is potentially dangerous
    Well, it's not dangerous, but the binary is not signed and hence, Windows warns about that issue. I don't want to judge whether that behaviour of Windows is good or bad in general but signing the program costs money. If you don't want Windows to annoy you with warnings you may self sign the program or ask me for a copy on a CD or usb stick which I provide for a small fee.

    On Android the program crawls! There's nothing to denay, it acually does. At least the graphics. The way the graphic ouput is implemented with this version is not optimized on Android...



    V1.4 released on 20.02.2019
    - introduction of a menu
    - internal clean ups
    - Android support (with the .hwa applet)

    V1.3 released on 26-Oct-2015
    - coordinate systems with labels
    - a few minor calculation glitches removed

    V1.2.3 released on 24-Sep-2015
    - User interface improved

    V1.2.2 released on 24-June-2015
    - new: version update availability notification (if online)
    - some internal changes

    V1.2.1 released on 15-May-2015
    - new: removed platform dependencies, applet file now available
    - new: autodetection of preferred language (English(default)/German)
    - changed: files get saved to sub directory "RB-files" of the program directory
    - improved: window arrangement is resolution aware now, UI polished a bit, autodetection of existing files with identical filename

    V1.2 released on 08-May-2015
    - new: save data as .png file
    - new: bilingual (English/German)
    - improved: population dynamics window with continuous data plot now
    - improved: UI polished a bit, introduction of a clearing cursor for RT and RA windows

    V1.1 released on 23-Apr-2015
    - new: show/hide button for the running average and population dynamic windows
    - improved: "virus" function placeholders for prey or predator viris outbreaks now with good functionality
    - plus improved internal parameters for some speed up

    V1.0 released on 02-Dec-2014
    - new: running average of the population
    - new: User interface now with three dedicated windows for more flexibility

    V0.10 released on 11-Nov-2014
    - new: sliders with digit output
    - improved internal parameters
    - minor design changes

    V0.9 released on 02-Nov-2014
    - initial public release



    Document history:

    26-Oct-2015 update for version 1.3
    24-Sep-2015 update for version 1.2.3, partially translated to German
    15-May-2015 update for version 1.2.1
    09-May-2015 update for version 1.2
    25-Apr-2015 update for version 1.1
    02-Dec-2014 update for version 1.0
    04-Nov-2014 this page started

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