Abstract from BTO Research Report No 312:

Henderson, I (March 03)

Birds Eye Walls: Partnership for Sustainability. Progress report on the use of pea fields.
ISBN 1-902576-63-2 1-902576-55-1

Executive summary

1. As part of Birds Eye Wall’s Partnership for Sustainability programme the BTO carried out a month by month breeding season survey of pea fields and adjacent crops, for birds on 20, 19 and 5 and 9 farm sites (for 1999, 2000, 2001 & 2002 respectively) in the east of England. The fieldwork included an intensive study of Skylarks on five East Anglian farms (using timed point counts). Elsewhere the spatial distribution of birds on peas was analysed in relation to pesticide versus non-pesticide treated field margins in 2001 and 2002 only.

2. The study revealed that higher densities of species and a greater abundance of most species were recorded on pea fields compared to cereal fields. This was true for seed-eating passerines (finches and buntings) also but for these species preferred crops were spring cereals or oilseed rape rather than peas. Peas were especially important for Lapwing (in Humberside) and Skylark (all sites) whose numbers approached those recorded on weedy fallows, and Yellow Wagtails were present in relatively high densities.

3. As a rule, in March bare soil was avoided by most species, and far greater use was made of sparse or developing pea crops (i.e. from April to June). Because of this, it was clear that farm activities, such as rolling, should best be performed either before April or quickly after the peas had been drilled, in order to protect the clutches of Skylarks and Lapwings.

4. Thrushes, finches and buntings occurred at higher densities nearer field boundaries, and would probably benefit from field margin conservation strips. From intensive studies, Skylarks would only use marginal strips where these occurred on open boundaries between two fields (e.g. beetle banks).

5. The majority of species occurred at higher densities on unsprayed margins than sprayed margins, but the difference was not statistically significant. The strongest difference was for insectivorous bird species (thrushes, wagtails and Dunnocks) and Grey Partridge but there was virtually no difference in the densities of buntings on the two treatment types.

6. Skylarks breeding on peas appeared to continue into June and possibly July, thereby potentially raising more offspring than on cereals. However, when not tied to a breeding site, birds used pea fields much less frequently and often foraged beyond the pea-field boundary. Overall, the mosaic created by pea crops, cereals and other crop types on rotational farms may help to maintain both foraging and breeding habitat for longer over the summer season.

7. The main focus of study should now concentrate on the species for which peas are especially important. These include Lapwings, Skylarks and Yellow Wagtails, although it is likely that other insectivorous birds would benefit (i.e. young Grey Partridge, thrushes, Dunnocks, Swallows and martins and Whitethroat), especially from reductions in herbicide or insecticide applications that can reduce invertebrate prey. For Lapwings, there may be additional field management criteria, such as the timing of rolling or drilling, that can be manipulated to help protect pairs that attempt to breed within pea crops.

Breeding Lapwings will form the basis of study in the proceeding year ahead. Attention will be focused on their frequency of occurrence within peas crops, management threats to breeding birds and their offspring and the foraging location and requirements of Lapwing broods.

Back to Research Reports 289 - 344