The breeding biology of magpies Pica pica in an urban environment

The colonisation of British cities by magpies is a recent phenomenon. This work presents an analysis of magpie breeding biology in the urban environment of south Manchester; laying date, nesting success, clutch size, incubation period, hatching success and nestling success have been investigated and where possible, are contrasted with the situation in rural areas. A proportion of magpies in Manchester renovate an old nest for the breeding attempt, a habit which is uncommon in rural populations. As a result of this, the average laying date for urban magpies is advanced relative to that of the surrounding rural areas. Another aspect of the urban breeding ecology which differed from that of rural magpies was the high frequency and success rate of repeat breeding attempts following an initial failure. These increased fledgling productivity by 25%, so that the average annual breeding sucess in the Manchester urban environment was 1·55 young per pair, which is one of the highest recorded for the magpie.