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| Intensive dairy farming has changed the agricultural grassland areas of The
Netherlands profoundly, with negative impacts on the reproduction of the shorebirds
breeding there. This modern agricultural landscape also forms a staging
site for migrating shorebirds, where they moult and replenish fuel stores, but
staging performance in these areas has received much less attention. We
studied northbound migrating Ruffs Philomachus pugnax staging in the grasslands
of southwest Friesland over a ten year period, during which peak numbers
declined from 20,000 in 2003 to 3500 birds in 2009 and then stabilized. On the
basis of resighting locations of individually marked birds, we describe changes in
their day-time foraging distribution from spring 2006 to spring 2013. Ruffs
progressively retreated to the centre of the c. 10,000 ha study area, where,
among intensive grasslands, established and newly created inland wetlands
occurred that served as feeding and/or roosting sites. To quantify the spatial
changes, in 2013 we repeated a transect survey of meadow use carried out
earlier in 2003. Using similar characteristics of individual meadows in terms of
herb richness (a measure of agricultural intensity) and landscape characteristics
(distance to the roost, soil type), we show that, during spring 2013, as in 2003,
Ruffs foraged preferentially on meadows close to roosting areas. The survey
also highlights the preference of Ruffs for the Workumerwaard, a particularly
large and open polder with a sandy soil and short vegetation bordered by a traditional
roosting area on the shoreline. This study provides some evidence that
inland wetlands may increase the attractiveness for migrating Ruffs of landscapes
dominated by modern grasslands. | |
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