Quantification of the nutrient input into freshwater habitats by waterbirds

In the last decades in Western Europe water bird populations  have increased probably as a result of decreased hunting pressure and enhanced food availability due to changes in agricultural practice. Because many herbivorous waterfowl are feeding away from lakes, on pasture and meadows, but still use these lakes for roosting, they are causing a nutrient input into these freshwaters.

The input of external nutrients may cause severe changes in the nutrient dynamics of lakes, especially if limiting elements (e.g. P and N) are being added. Notably if we consider the estimated 200 million geese and swan days for the whole of the Netherlands per winter (!), it is evident that allochthonous, bird-borne nutrient input to freshwater systems may play a considerable role in the nutrient dynamics of these ecosystems.
But also carnivorous birds may impact the nutrient dynamics of freshwater systems. Because of their mobility, also carnivorous waterbirds may contribute to a redistribution of nutrients across lakes.

Water birds 1.1

Water birds 1.1 is a computation tool to estimate the nutrient input of various water bird species into freshwater habitats in Europe. Main focal area of application includes central Europe and particularly the Benelux. All calculations based on models published in the following articles:

• Herbivore part: Hahn, Bauer & Klaassen (2008)
  Quantification of allochthonous nutrient input into freshwater bodies by herbivorous waterbirds. Freshwater Biology online 11/2007 http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2427.2007.01881.x
• Carnivore part: Hahn, Bauer & Klaassen (2007)
  Estimating the contribution of carnivorous water birds to nutrient loading in freshwater habitats. Freshwater Biology 52 (12), 2421-2433. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2427.2007.01838.x

The model includes only those bird species that can be encountered in the Netherlands and might be of relevance for nutrient input into freshwaters. For herbivores, we considered only those water birds, which are known to feed at least temporarily in terrestrial habitats based on data published in (Cramp 1998) and Glutz von Blotzheim (1990). For carnivorous birds we included species which are abundant in the Dutch mainland either as migrants/visitors or as breeding birds. All species are given by their common (English) names. If other or more species should be included, the input file 'Input_Birds.txt' can be adjusted (see HELP for instructions).

To start the program:
Download the zip file into a new folder and unzip it. Double-click ‘Waterbirds.exe’ to start the program. In the program-window, select bird species, time periods and food types for which you want to calculate the nutrient input.

Contact:
Steffen Hahn: steffen.hahn@vogelwarte.ch 
Silke Bauer: s.bauer@nioo.knaw.nl 
Marcel Klaassen: m.klaassen@nioo.knaw.nl