If managed sympathetically cropped areas can also provide valuable habitat for arable plants, birds and mammals. Conservation headlands, which have reduced inputs from insecticides, herbicides and fertilisers, benefit farmland bird species that have suffered the most extensive declines, such as grey partridge Perdix perdix, corn bunting Emberiza calandra and turtle dove Streptopelia turtur, with the last showing the greatest decrease of any species, 93% since 1994. Turtle doves have suffered a 93% UK population decline since 1994, and research shows that the number of chicks they are producing has halved since the 1970s.
Banbury Ornithological Society (BOS) conducts what is probably the longest running survey of winter farmland birds anywhere in the country. This is the “Winter Random Square Survey” which started in 1975 and is continuing to this day. It measures the abundance and distribution of around 40 common species. This survey has shown that several resident farmland birds, including yellowhammer and linnet, declined greatly in the 70s and 80s, before stabilising somewhat in the late 90s and 2000s. For a few, the declines are continuing, notably corn bunting Emberiza calandra and tree sparrow Passer montanus.
Small farmland mustelids, such as the weasel Mustela nivalis and stoat Mustela ermine are lacking county data due to difficulties in robustly assessing population size. Both considered declining species in 1998, opportunistic anecdotal evidence suggests that both species are still widespread throughout the county. The harvest mouse Micromys minutus, arguably the most iconic farmland mammal, is also currently lacking data to determine population status and trends but recent surveys by the Oxfordshire Mammal Group should provide a better picture of their status for future reports.