Page:Territory in Bird Life by Henry Eliot Howard (London, John Murray edition).djvu/248

190 that the boundaries were to cease to exist, and that the birds were free to wander at will without fear of molestation, the end for which the territory had been evolved would none the less have been obtained; for inasmuch as the parents are accompanied by their young, it matters not in what part of the meadow they seek their food; all that matters is that the number of families shall not exceed the available supply of food. So far, then, as the Lapwing is concerned, the territory fulfils its purpose when once it limits the number of males, since, by doing so, it limits the number of families and prevents undue pressure upon the means of support.

Nevertheless, there are many birds that seem to rely entirely upon the territory to supply them with all that is necessary. Each Warbler seeks its food within the precincts of its own particular domain, and, except in occasional instances, neither resorts to neutral ground nor makes excursions into the locality immediately surrounding the territory, as does the Bunting. Probably it would be disastrous if it attempted to do so, for since its young at birth are so delicate and so susceptible to changes of temperature, it cannot afford to be absent from them for long. Of the two experiments made with young Whitethroats, one was made under favourable and the other under unfavourable conditions. In this latter case the temperature was 50°&thinsp;F., and the young, it may be remembered, only survived for a