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Voedselecologie en gedrag van overwinterende watervogels langs de Zeeschelde: een methodologische studie

Onderzoeksoutput: Boek/rapportRapporten van het Instituut voor Natuur- en Bosonderzoek

Auteurs

Details

Originele taal-2Nederlands
UitgeverijInstituut voor Natuur- en Bosonderzoek
Aantal pagina's111
StatusGepubliceerd - 2006

Publicatie series

Naam Rapporten van het Instituut voor Natuur- en Bosonderzoek
UitgeverijInstituut voor Natuur- en Bosonderzoek: Brussel
Nr.INBO.R.2006.28

Abstract

Context and aims

This methodological study is the result of a 6 month desk study as part of the research andmonitoring program embedded within the long-term vision for the Scheldt estuary (LTV O&M).

The need for this study results from the conclusion that, although results of long-term monthly monitoring of waterfowl show the regional and international importance of the Seascheldt for wintering water birds, we still have little understanding on the precise key features of the estuary underlying this importance. Nevertheless this knowledge is important if we want to understand and evaluate anthropogenic and natural changes in the Scheldt estuary in relation to its function as waterfowl habitat.

The questions underlying this study are complex and need an interdisciplinary approach assembling information from various scientific fields (behavioural ecology, demographical ecology, estuarine ecology,…).

Because we don’t know which approach would be the most efficient and tractable method to resolve these complex questions, we evaluate the different methodologies possibly clarifying the posed problems. Moreover, there is need for a strategic plan to investigate the ecological functions of the Seascheldt for wintering and migrating birds.

Results

Based on a literature study and expert judgement we evaluate different research techniques. All methods are tested against the specific conditions in the Seascheldt and against their ability to answer the specific research questions. The feasibility (time investment, logistic needs and financial consequences) and expected results of each method are summarized. Based on this knowledge different research strategies are formulated.

In chapter 4 a survey of the existing datasets in the Scheldt estuary and the current knowledge about five important water bird species (Shelduck, Common teal, Gadwall, Pintail and Pochard) is presented. Next all research techniques are discussed and evaluated (chapter 5). Each discipline (bird trapping, diet research, foraging research, habitat use, wintering strategy and modelling techniques) is evaluated in general and recommendations are formulated in chapter 6.

Conclusions

  1. Long term datasets (bird counts, benthos spatials, habitat maps and characteristics,….) are extremely valuable; they form the basis for future research and should by all means be continued.
  2. However, the existing datasets should be explored more thoroughly and interrelated. Some datasets where never reported before or can reveal more useful information. Some of the datasets should be explored and combined by use of a Geographic Information System.
  3. For each promising technique listed a pilot study is necessary. This is because none of the techniques could be fully evaluated as 1) present knowledge is too limited; 2) the method was never tested before on ducks; 3) we must test whether the technique is practible in the specific conditions posed by the Seascheldt ecosystem (bird trapping techniques, exclosures, telemetry).
  4. There is urgent need for direct observation on the diet of waterfowl in the Seascheldt to model and monitor water birds. Benthos (Oligochaeta) are probability the main food source but this must be confirmed.
  5. Anticipating on the assumption that benthos is indeed the main food source, there is need for knowledge on the relationship between abiotic variables and benthic organisms.

Recommendations – research strategy

The formulated research strategy uses a figurative locomotive to pull several smaller research studies as carriage in a flowchart approach. On the first level three work hypotheses are formulated. All ask for a spatial model approach. We propose to combine the datasets in a GISenvironment.
The work hypotheses are:

  1. There is a significant correlation between bird density and sediment characteristics
  2. There is a significant correlation between bird density and habitat quality parameters (abiotic)
  3. There is a significant relation between bird density and water quality
To investigate wintering strategy of waterfowl an international approach is needed. Some possible tracks are formulated.

Proposed research strategies will eventually result in models able to predict/evaluate to some extent effects of:

  • deepening of the Scheldt (European Habitats and Species Directives)
  • mitigating and compensating measures (European Habitats and Species Directives)
  • water quality changes (European Water Framework Directive) on the functionality of the Seascheldt in its international context as a wintering area for water birds (Ramsar, European directives).

Additionally the results will give us a better understanding of

  • the way forward to reach the conservation objectives (European directives)
  • The carrying capacity of the Scheldt estuary
The proposed research strategies fill the present gaps in our knowledge and supply the policy maker with background information.

EWI Biomedische wetenschappen

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