British farmland birds are in trouble. Since recording began in 1970 they have experienced an overall population decline of 56%, with some species decreasing by over 90%. Intensification of farming practices aiming at increasing agricultural yields has been widely linked to these declines, especially the systematic removal of key habitats, such as hedgerows and wet meadows. Such changes have reduced food availability for birds, both when raising chicks and also over winter. A further major change since the 1970s is the widespread neglect of farmland ponds, which, due to the cessation of traditional management practices, have become overgrown by scrub, or at worst filled in.
Building on some previous work of the Pond Restoration Research Group (Davies et al. 2016), my PhD research, as part of the London NERC Doctoral Training Partnership, is investigating the role that pond management plays in supporting farmland birds. 16 study ponds are the focus of the research, divided into two groups; managed, open ponds (Figure 1) and non-managed, overgrown ponds (Figure 2). Since April I have been visiting these ponds on a weekly basis to record bird activity. I will continue to do this until the end of March next year, providing a detailed seasonal record of bird activity and usage at the ponds. Despite being just six months in, my research is already offering valuable insights into how pond management can help to support birds.
Figure 1. A managed pond, rich in invertebrate life and seeds, provides a variety of food sources for birds
Figure 2. An unmanaged pond offers fewer invertebrates and seeds for birds
Over the spring and early summer months, I recorded a higher number and greater diversity of birds at the managed ponds. This most probably relates to a higher abundance of insect life found at managed ponds, combined with a more varied surrounding vegetation which offers prime opportunities for nesting. Sharp spikes in bird activity in May and June were synchronised with mass mayfly hatches, which provide food for both adult birds and their young. In comparison, unmanaged ponds were visited by fewer birds, comprising a lower diversity of species. Common woodland and garden birds, such as wren and robin, have mainly been seen around the unmanaged overgrown ponds, whereas a wide range of species (and importantly a higher proportion of scarce and threatened species), including yellowhammer (Figure 3), linnet, snipe, grey wagtail and swift have been recorded at the managed ponds.
Figure 3. Yellowhammer have declined by 54% since 1970 (copyright Francesco Veronesi)
This autumn there has been a shift in feeding behaviour – invertebrate numbers have dwindled and many bird species are now focusing on seeds and fruits around the pond margins. Linnet, goldfinch, bullfinch and brambling have been recorded eating the smaller seeds alongside fieldfare and redwing which have been observed eating fruits from bankside bushes. As winter sets in it will be interesting to see how birds respond to both colder temperatures and continually reducing food sources in the farmland. Will they flock to the ponds when the going gets tough?
Further experiments and surveys over the next two years will aim to unravel exactly how managed ponds support farmland birds, with the aim of influencing agri-environment policy such that farmers are more encouraged to manage ponds to the benefit of birds and all sorts of other wildlife. I will share my findings as they happen through this blog and via my twitter feed @norfolkwildlife
Davies, S.R., Sayer, C.D., Greaves, H., Siriwardena, G.M. & Axmacher, J.C. (2016) A new role for pond management in farmland bird conservation. Agriculture, Ecosystems & Environment, 233, 179-191. doi.org/10.1016/j.agee.2016.09.005