Page:The British Warblers A History with Problems of Their Lives - 4 of 9.djvu/19

 dangers attendant on migration, &c.—which materially affect their numbers, causing a certain deficiency universal in some years.

When large numbers of individuals arrive simultaneously, I have often noticed that a considerable proportion of them are immature birds with undeveloped plumage and colour lacking in intensity; and so much is this sometimes the case that it is by no means easy to find a male with the breast suffused with the vinous tint, so prominent a beauty of a really adult bird. The plumage of the males varies; some have much richer colouring and a greater development of feather; this I believe to be largely due to age, but until we have further information with regard to the spring moult it is impossible to say how much this may be the case. The majority of the males upon arrival in this country appear to have only recently completed their moult.

Where plentiful they add considerable charm to the country roads and lanes, which they love to inhabit, for they are generally singing, uttering their peculiar hissing note, or performing a series of aerial dances. Tall and tangled hedgerows, especially by the side of the road, are their favourite resorts; but they are found in various places, such as wooded banks with luxuriant undergrowth, osier beds, gardens, the more open parts of large forests where the timber has recently been felled, and the outskirts of woods and coppices, the only real necessity to them being thick and tangled undergrowth, in which they can quickly conceal themselves and ultimately rear their young. In all such places they are not only very plentiful, but, in contrast with so many wild creatures, make their presence known—in fact, almost intrude themselves upon one by their apparent inquisitiveness.

It often happens that solitary males make their appearance some few days ahead of the general bulk of the species; but they differ somewhat from other migratory species in this, that they do not increase so gradually, but arrive more