CANCELLED - Experimental hedgerow removal results in negative effects on bird diversity and bat richness, but not frog richness: a before-after-control-impact study

Background/Question/Methods

Agricultural land cover now occupies more than 40% of the ice-free surface area of the earth and is one of the largest drivers of biodiversity loss globally. This is because agro-ecosystems often lack natural and semi-natural land covers that support wildlife. In Europe, there is increasing evidence that hedgerows or strips of linear woody vegetation along field margins provides habitat for many different wildlife species. However, in North America, similar research is generally lacking. We conducted a before-after-control-impact study in eastern Ontario Canada, where we experimentally removed the hedgerow along a 4 km drainage ditch while leaving the hedgerow intact along a parallel drainage. We also dredged the treatment drainage the year following vegetation removal. Hedgerow removal and dredging are common practices used by farmers and conservation authorities to improve water flow in the drainages in our research area. Along each drainage, we measured bird diversity and abundance using point-counts every 200 m, as well as bat and frog richness and activity/abundance using recording devices every 400 m along each drainage across the three years of our experiment.

Results/Conclusions

We found that hedgerow removal negatively impacted bird diversity and bat richness, but had a positive effect on frog richness. We also found that dredging had a negative effect on frog abundance, but had no effect on either bird abundance or bat activity. Our results suggest that a mosaic of intact and cleared hedgerows needs to be maintained along drainages within agro-ecosystems in our study region to maximize biodiversity.