Individual study: Effect of herbicide spraying on densities of red-winged blackbirds Agelaius phoeniceus, yellow-headed blackbirds Xanthocephalus xanthocephalus and marsh wrens Cistothorus palustris in wetlands near Lakota, North Dakota, USA
Linz G.M., Blixt D.C., Bergman D.L. & Bleier W.J. (1996) Responses of red-winged blackbirds, yellow-headed blackbirds and marsh wrens to glyphosate-induced alterations in cattail density. Journal of Field Ornithology, 67, 167-176
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Treat wetlands with herbicide
A controlled, replicated before-and-after study in 1990-1993 in 23 inland wetlands in North Dakota, USA (Linz et al. 1996), found that the densities of three songbird species were all significantly lower on sites sprayed with glyphosate, than on unsprayed sites (red-winged blackbirds Agelaius phoeniceus: 0.6 birds/ha on sites where 90% of the site was sprayed vs. 1.6 on controls; yellow-headed blackbirds Xanthocephalus xanthocephalus: average of 2.1 birds/ha on all treated sites vs. 3.1 on controls; marsh wrens Cistothorus palustris: 0.7 birds/ha on treated sites vs. 2.2). Experimental wetlands had significantly lower percentage covers of emergent vegetation. Sites were sprayed from the air with either 90%, 70% or 50% of the site treated. There were no differences between sites before herbicide application.