The arable wildlife south of Cambridge

For the last eleven years I have surveyed breeding populations of farmland birds on a square kilometre of green belt on the southern fringe of Cambridge, to assess the levels of the biodiversity of an area close to the city. I have written a book about my study, entitled A haven for farmland birds.

Over the eleven years I have in total recorded 94 bird species. These include 18 of the 19 farmland bird indicator species for the Sustainable Development Strategy, of which 14 breed, and 22 red list species of high conservation concern, of which 10 breed. My most recent survey of the area – which you can download below – showed exceptional numbers of grey partridge in the autumn (right) and corn bunting (below left), as well as good numbers of skylark, linnet, yellowhammer (below centre) and yellow wagtail (below right). Grey partridge declined by 93% between 1970 and 2018 and corn bunting by 89% while yellow wagtail declined by 68%, skylark by 60%, yellowhammer by 56% and linnet by 55%.

In 2021 the area supported a grey partridge population of at least 18 spring pairs/km² and 90+ birds/km² in autumn. The arable farms typical of Cambridgeshire support between 0 and 5 pairs/km² and 0–20 birds/km² in the autumn.

Corn buntings did particularly well in 2022, with 11 pairs. This is an important population – there are just 11,000 birds in the UK and its recent extinction in Ireland risks being repeated in large parts of Britain if its breeding sites are not protected.

In addition, the site supports thriving populations of water voles – in Hobsons Brook and the ditch that runs alongside the cycle path – and at least 20 brown hare.

I also survey butterfly and dragonfly populations in the area; the 25 species of butterfly I have recorded include brown argus (below left), clouded yellow, small copper (below centre) and small heath (below right).