Patches of bare ground as a staple commodity for declining ground-foraging insectivorous farmland birds.

Conceived to combat widescale biodiversity erosion in farmland, agri-environment schemes have largely failed to deliver their promises despite massive financial support. While several common species have shown to react positively to existing measures, rare species have continued to decline in most European countries. Of particular concern is the status of insectivorous farmland birds that forage on the ground.

Site-occupancy distribution modeling to correct population-trend estimates derived from opportunistic observations.

Species' assessments must frequently be derived from opportunistic observations made by volunteers (i.e., citizen scientists).