For the last thirteen 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 thirteen years I have in total recorded 107 bird species, of which 51 have bred. 
These include 18 of the 19 farmland bird indicator species, of which 15 have bred, and 22 red list species of high conservation concern, of which 12 have bred. My most recent survey of the area – which you can download below – showed good numbers of grey partridge (right) and corn bunting (below left), as well as 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 2024 the area supported a grey partridge population of at least 14 spring pairs/km2 and around 42 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. These numbers are lower than the 18 pairs and 90+ birds in 2021. Several factors may have contributed to this – in particular the crop made counting autumn birds more difficult – but it does seem likely that the continued expansion of the Biomedical Campus and associated disturbance may be forcing the birds into a smaller area away from the development.
Corn buntings held 11 territories. This is an important population – there are just 11,000 pairs in the UK and their recent extinction in Ireland risks being repeated in large parts of Britain if their 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).
You can download a copy of my report for 2024 here:
The local plan
The area I study is currently green belt. However the local councils have already released the two fields closest to the Biomedical Campus for development, and one of these (Field 1 on my maps) has already been built on and is no longer suitable for any of the farmland species. Planning applications for the second field (Field 2 on my maps) are likely before long and I will post links here.
In the next local plan the councils are likely to propose releasing two further fields (Fields 7 and 8 on my maps) from green belt for development, and this would have a negative impact on the farmland birds that live there.
The local plan had been on hold until recently but is now underway again. The councils are currently providing an opportunity for ‘developers, landowners and others’ to contribute, ahead of the ‘Proposed submission consultation’ this autumn or early winter. The timetable is now available here. where you can also sign up for updates from Greater Cambridge Planning.
In the meantime I will continue to liaise with councillors, planners and landowners to make sure that they are aware of the wildlife value of the area. You can raise the issue with your local councillors and read/download my response to the previous consultation here:
Past reports
My report for 2023 is here:
My report for 2022 is here:
My report for 2021 is here:
My report for 2020 is here:
My report for 2019 is here:
My report for 2018 is here:
My report for 2017 is here:
My reports for 2016 are here:
My reports for 2015 are here: