Direct and indirect effects of the most widely implemented Dutch agri-environment schemes on breeding waders

Published source details Verhulst J., Kleijn D. & Berendse F. (2007) Direct and indirect effects of the most widely implemented Dutch agri-environment schemes on breeding waders. Journal of Applied Ecology, 44, 70-80.
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This study is summarised as evidence for the following.

	Action	Category
	Offer per clutch payment for farmland birds Action Link
	Delay haying/mowing Action Link
	Make direct payments per clutch for farmland birds Action Link
	Delay mowing or first grazing date on pasture or grassland Action Link

Offer per clutch payment for farmland birds

A replicated and controlled paired sites study in the western Netherlands in 2003 (Verhulst et al. 2007) found slightly higher breeding densities of birds on 19 grassland plots with per-clutch payments for wader clutches, compared to 19 paired, control plots, both when delayed mowing was also used and when per-clutch payment was the only scheme used (13 territories/plot for combined schemes; 13 territories/plot for per-clutch payment and 11 territories/plot for controls). However, birds were not more abundant under either scheme, compared with controls (approximately 125 birds/plot for combined schemes; 125 birds/plot for per-clutch payment and 110 birds/plot for controls). Wader breeding densities were higher (but not significantly so) on combined and per-clutch payment plots (approximately 7 territories/plot for combined schemes; 7 territories/plot for per-clutch payment and 5 territories/plot for controls). When individual wader species were analysed, there were higher numbers of redshank Tringa totanus on combined or per-clutch payment plots (approximately 5 birds/plot for combined schemes; 5 birds/plot for per-clutch payment and 3 birds/plot for controls), but there were no significant differences in breeding densities for redshank, northern lapwing Vanellus vanellus, Eurasian oystercatcher Haematopus ostralegus or black-tailed godwit Limosa limosa. The authors suggest that groundwater depth, soil hardness and prey density drove these patterns. All farms had been operating the schemes for at least three (and an average of four) years before the study. This study is also discussed in ‘Delay haying/mowing’.
Delay haying/mowing

A replicated and controlled paired sites study in the western Netherlands in 2003 (Verhulst et al.) found that 19 grassland plots with delayed mowing had significantly higher breeding densities of waders, compared to 19 paired, control plots (approximately 8 territories/plot for delayed-mowing plots vs. approximately 3 territories/plot for controls). This difference was not apparent when delayed mowing was combined with per-clutch payment, and there were no differences in abundances of waders or all bird species. However, when delayed mowing was combined with per-clutch payment, breeding densities of all bird species was significantly higher (13 territories/plot for combined schemes; 11 territories/plot for controls). There were higher numbers of redshank Tringa tetanus on combined plots (approximately 5 birds/plot for combined schemes; 5 birds/plot for per-clutch payment and 3 birds/plot for controls), but not on delayed-mowing plots. There were higher abundances of northern lapwing Vanellus vanellus on control plots, compared to delayed-mowing plots, but this difference was not significant (approximately 18 birds/plot for controls vs. 13 birds/plot for delayed-mowing plots). There were no significant differences in breeding densities for redshank, northern lapwing, Eurasian oystercatcher Haematopus ostralegus or black-tailed godwit Limosa limosa. The authors suggest that groundwater depth, soil hardness and prey density were drove these patterns. All farms had been operating the schemes for an average of four years before the study. This study is also discussed in ‘Offer per-clutch payment for farmland birds’.
Make direct payments per clutch for farmland birds

A replicated and controlled paired-sites study in the western Netherlands in 2003 (Verhulst et al. 2007) found slightly higher breeding densities of birds on 19 grassland plots with per-clutch payments for wading bird clutches, compared to 19 paired, control plots, both when delayed mowing was also used and when per-clutch payment was the only scheme used (13 territories/plot for combined schemes, 13 territories/plot for per-clutch payment and 11 territories/plot for controls). However, birds were not more abundant under either scheme, compared with controls (approximately 125 birds/plot for combined schemes, 125 birds/plot for per-clutch payment and 110 birds/plot for controls). Wader breeding densities were higher (but not significantly so) on combined and per-clutch payment plots (approximately 7 territories/plot for combined schemes, 7 territories/plot for per-clutch payment and 5 territories/plot for controls). When individual wader species were analysed, there were higher numbers of redshank Tringa totanus on combined or per-clutch payment plots (approximately 5 birds/plot for combined schemes, 5 birds/plot for per-clutch payment and 3 birds/plot for controls), but there were no significant differences in breeding densities for redshank, northern lapwing Vanellus vanellus, Eurasian oystercatcher Haematopus ostralegus or black-tailed godwit Limosa limosa. The authors suggest that groundwater depth, soil hardness and prey density were drove these patterns. All farms had been operating the schemes for at least three (and an average of four) years before the study.
Delay mowing or first grazing date on pasture or grassland

A replicated and controlled paired-sites study in the western Netherlands in 2003 (Verhulst et al. 2007) found that 19 grassland plots with delayed mowing had significantly higher breeding densities of wading birds, compared to 19 paired, control plots (approximately 8 territories/plot for delayed-mowing plots vs approximately 3 territories/plot for controls). This difference was not apparent when delayed mowing was combined with per-clutch payment, and there were no differences in abundances of waders or all bird species. However, when delayed mowing was combined with per-clutch payment, breeding densities of all bird species were significantly higher (13 territories/plot for combined schemes, 11 territories/plot for controls). There were higher numbers of redshank Tringa totanus on combined plots (approximately 5 birds/plot for combined schemes, 5 birds/plot for per-clutch payment and 3 birds/plot for controls), but not on delayed-mowing plots. There were higher abundances of northern lapwing Vanellus vanellus on control plots, compared to delayed-mowing plots, but this difference was not significant (approximately 18 birds/plot for controls vs 13 birds/plot for delayed-mowing plots). There were no significant differences in breeding densities for redshank, northern lapwing, Eurasian oystercatcher Haematopus ostralegus or black-tailed godwit Limosa limosa. The authors suggest that groundwater depth, soil hardness and prey density drove these patterns. All farms had been operating the schemes for an average of four years before the study.