Organisatieprofiel

Meadow Bird Ecology

Approximately 60% of the land area of ​the Netherlands consists of agricultural land and more than half of that is pasture. Many bird species use these grasslands to breed, feed or rest. The Netherlands hosts a significant portion of the world population of some of these species and we use for the diverse group of breeding birds even a typical Dutch word: "weidevogels" which means meadow birds. But also outside the breeding season, grasslands are important for various species of waders.

The populations of breeding wader species as black-tailed godwit, lapwing, oystercatcher and redshank, that were common 30 years ago, are now under heavy pressure. The scale up and intensification of land use has changed the agricultural fields dramatically and has had a negative impact on nearly all bird populations. Setting reserves and the large-scale implementation of agri-environmental schemes have not prevented that in many places meadow birds have almost disappeared or severely decreased. We are curious if meadow birds can cope with these changed circumstances.

Non-breeding waders use the grasslands as foraging and resting area in winter or during migration to and from the breeding grounds. Well-known examples are ruff, golden plover and curlew. Until recently it was assumed that these species were able to survive in the highly modified agricultural landscape but in the last decade the numbers of migratory ruffs are decimated while golden plovers have moved more towards the coast. That raises the question to what extent the Dutch grasslands are still suitable for these species.

Our group has a long tradition in the field of wader research. In 2004 we therefore started with two long-term studies in the grasslands of southwest Friesland, a key area for both categories of "waders". We chose the black-tailed godwit as model species for breeding wader species, while migrating and wintering waders are represented by ruff and golden plover.

Intertidal foodweb studies

The variety of shorebirds that feature as research subjects in some of the above themes, have themselves generated a long tradition of in-depth studies on foraging and energetics in which our group was involved. Studies on food selection and intake rates by the shorebirds eating intertidal invertebrates naturally lead to focussed studies on the antipredation behaviour of these prey. The work on bivalve-specialist shorebirds such as red knots, oystercatchers and eiders, has thus spawned studies on the life-history, population genetics and biogeography of important mollusc prey, especially the Baltic tellin and its many Tellinid relatives. This work has usually been carried out in close co-operation with sister institutes, especially the Royal Netherlands Institute for Sea Research (NIOZ) on Texel, in their research programmes on intertidal foodwebs and coastal marine community structure. The very fact that many of the shorebirds studied in the Wadden Sea migrate onwards to intertidal areas elsewhere has opened opportunities for comparative work on population biology, foodwebs and community structure of intertidal soft sediment systems worldwide. Currently our group is involved in such studies in the Wadden Sea, West-Africa and Northwest Australia, usually with a focus on the role of molluscivore shorebirds and their bivalve prey.

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