02 Sep 2013
'Where have all my birds gone?' is a question that the BTO's Garden Ecology Team hears a lot at this time of year. One of the most conspicuous disappearances from British gardens at the end of the summer is that of the Blackbird. September and October see the lowest reporting rate in Garden BirdWatch as adult Blackbirds complete their moult and all age groups disperse into the wider countryside to take advantage of the bounty of natural food. It isn't until November that the GBW reporting rate picks up again.
In contrast the BirdTrack reporting rate increases steadily throughout September and October. The latter part of this increase is probably a result of contintental immigrants arriving and resident birds moving around to find suitable wintering areas. The September element of the increase is more likely to be due to the steadily-increasing detectability of British and Irish Blackbirds (in the wider countryside, rather than gardens) as they complete their post-breeding moult.