Invertebrates are a major component of chickfood for many farmland bird species

Invertebrates are a major component of chickfood for many farmland bird species: chaffinch (Fringilla coelebs), cirl bunting (Emberiza cirlus), corn bunting (Miliaria calandra), goldfinch (Carduelis carduelis), greenfinch (Carduelis chloris), grey partridge (Perdix perdix), house sparrow (Passer domesticus), quail, red-legged partridge (Alectoris rufa), reed bunting (Emberiza schoeniclus), rook (Corvus frugilegus), skylark (Alauda arvensis), stone curlew (Burhinus oedicnemus), tree sparrow (Passer montanus), yellowhammer (Emberiza citrinella) and yellow wagtail (Motacilla flava).

Source: DEFRA EPG 1/5/188
https://www.dur.ac.uk/philip.stephens/DefraDocs/FullReport-ish.pdf