Whilst attempting to discourage pigeons from eating a local farmers oilseed rape this weekend I noticed a significant number of fieldfares in a large flock descending on and working the crop which had been established behind a subsoiler. There was a good stubble present as well as a strong crop canopy - given the harsh winter and limited remaining hedgerow fruit are they driven to foraging in such situations or is this standard practice for the time of year?
I have always viewed mintill/autocast osr to be the ideal combination of stubble and brassica canopy especially for game birds but was not sure of what benefit it was for farmland birds in general.
Hi Richard
Whilst fieldfares and other thrushes will take fruit whenever this is available, they are primarily invertebrate feeders, and predominantly feed on invertebrates in open fields, both arable and pastoral. They may well have been feeding on slugs and earthworms in this case? A study of fieldfare diet in Britain (Sep - May) in 1920's (ref in 'Birds of the Western Palearctic') found it was composed of 37.5% insects, 14.5% earthworms, 4.5% slugs, 2.5% other inverts, 36% fruit and seeds and 5% other plant material.
There have been studies showing some evidence for more use of min till fields by seed-eating birds through the winter (eg ref below*), but I have often wondered about the soil invertebrate abundance of min till fields after a winter visit to one farm where the fields were full of golden plovers and fieldfares, and I discovered that they had not been ploughed for at least five years.
*Field RH, Benke S, Badonyi K & RB Bradbury (2007) Influence of conservation tillage on winter bird use of arable fields in Hungary. Agriculture, Ecosystems & Environment, 120: 399-404.
Hmm, good point. I've seen plenty of fallen crabs still available too. Some have just turned to brown mush of course, but I wonder why more things are eating them?