Investigation on the environmental influence of hang- and paragliding on bird populations.

In accordance with German law, the DHV is required to evaluate and certify flying sites before they may be used. A part of this certification process involves consultation with nature-conservation authorities. As hang- and paragliding are both sports which take place outdoors, conflicts of interest may exist between conservationists and pilots.

In the past, differing opinions on the influence of hang- and paragliding on bird populations have been the source of much controversial discussion. In some cases conservationists feared severe disturbances to birdlife, particularly in regions close to launch- and landing-sites.
In order to be able to make objective decisions on the impact of hang- and paragliding on bird populations, the DHV commissioned the above named investigation with Zukunft Biosphere GmbH, a company specialising in environmental studies.Initially two environmentalists HÜPPOP & KEMPF (1998) formulated methods and procedures which should ensure a scientifically correct investigation. These were followed carefully and are outlined below:

1. An ornithological study of 10 different flying-sites throughout Germany, which are characteristic for a particular habitat.
2. For unbiased results, the investigators should be independent qualified ornithologists with local knowledge of the site to be investigated.
3. To record all bird species (nesting, migratory, foraging etc.) observed on the site, with particular emphasis on those included on the endangered list.
4. To evaluate whether song-birds breed in the near vicinity of launch fields. (Main investigatory theme).
5. To evaluate the population density of all bird species present on the site.
6. To compare the results with expected averages for the sites chosen.
7. To compare the results with those from previous studies.
8. To estimate to what degree the results may be valid for other sites.

Important note: for the interpretation of the results, validity estimations and appropriate environmental recommendations, Zukunft Biosphere GmbH relied on the impartial recording work of the investigators, and objective information from land owners.

Summary of results

The main goals of this investigation were to determine whether bird breeding is reduced or bird populations are depleted in the near vicinity of flying sites.
In addition to these goals, complete diversity and population counts were made for nesting, foraging, migrationary and otherwise present birds within the entire sites. The evaluation methods used indicate that in most of the sites investigated, balanced populations of almost all bird species exist. This is also true for flying sites which have been in use over periods of several years.

The absence of some species of birds which were normally to be expected in certain habitats was not generally attributed to hang- and paragliding. The investigators rated factors such as the evaluation procedures used, local habitat destruction or other external influences as more significant within the results than the presence of hang- and paragliders.
In some of the sites investigated, it was recommended that in order to secure bird populations, the preservation of current vegetation was more important than a reduction in air traffic.

The populations of breeding birds within the sites investigated, lie for the great majority, within the tolerance for the central European maximums which are to be expected for similar habitats. In a few cases, more significant deviations were noted, which could be interpreted as being due to habitat changes due to hang- and paragliding. It is however, not possible to conclude that these deviations are directly related to hang- and paragliding activity without further study. For certain sites further investigations to resolve this question should be undertaken.

It is only possible to make a limited generalisation of the validity of these results for alternative flying sites. However it would appear, that under similar environmental conditions, predictions as to the expected species diversity and bird populations, and their sensitivity to hang- and paragliding can be made from these results.

Forecasts on breeding success rates and other population regulatory factors, and predictions on changed behaviour patterns as a direct result of hang- and paragliding activity were not goals set in this investigation. In addition to this, the results of this investigation are an indication of the present status quo, and cannot therefore be taken as a forecasts for future changes (e.g. air traffic increase or habitat alterations).