This is undoubtedly our most plentiful breeding types of land bird, and although its fine song is restricted to a comparatively short season, whatsoever other times it is constantly on the give audible notice of their presence, for this is one of the chief alarmists of garden, hedgerow and woodland; also, during wintertime, it is as noisy as the pheasant in advertising the proven fact that it is going to roost.
While not a sociable species in the same manner as redwings and fieldfares, roosting assemblies of from twenty to some hundred birds are very usual, and the quantity of chasing and rivalry exhibited before the flock settles down, and the preponderance of males, shows that this is a pre-mating ritual as opposed to a mere roosting assembly.
Usually at the morning hours dispersal from this type of roost, blackbirds may be seen feeding with what may be thought to be a very widely-spaced flock, and the other characteristic-that of never venturing not even close to the cover of hedge or trees-may then be noted.
Blackbirds and song thrushes, the two commonest medium-sized birds of garden and hedgerow, share many food-gathering activities-searching lawns and meadows for earthworms, following the gardener's spade or fork for worms or grubs, and pecking fruit and eating berries. However in spite of the song thrush's superiority in the few making use of snails, the blackbird is the better adapted of the two with regards to procuring food in difficult times.
Its greater bulk certainly provides it with some slight advantage in resisting extreme cold, but the more essential factor in helping it to outlive is its digging and scuffling technique which enables it to locate food beneath leaf-litter when none can be obtained on the surface; proof of this strength of feet isn't confined to the tell-tale debris on the snow at the hedge-bottom-the gardener's mulch of humus might be similarly scattered throughout a droughty summer.
The distinctive plumage of the cock blackbird causes it to be an unmistakable bird, but the same can't be said of females and young; for this type of common garden-nesting species, it's amazing how often the brown hen leads individuals to conclude (and report) that the mixed marriage has had place from a thrush along with a blackbird. The first-year male, changing from juvenile to adult plumage from early August onward, look very odd inside a parti-coloured coat containing large patches of both the new black and the old mottled brown.
Regardless of its ability to deal with hard weather, the blackbird isn't entirely a static resident; some part of our population moves, usually to milder western areas and Eire, at the approach of winter, and our winter numbers are considerably augmented by immigrants from across the North Sea. As these European birds (unlike Continental song thrushes) are indistinguishable from your native birds in plumage or behaviour, arriving is not so obvious as those of the fieldfare and redwing; but, often coinciding with the arrival of the last two species, sudden increases in blackbird numbers might be noted-and at night the 'sip' flight-call might be heard. The recovery of marked birds shows that the countries around the Baltic are the breeding-haunts of those winter immigrants.