While the (true nature of birds' te

While the (true nature of birds' territories has
proved very elusive (Lack 1954, Hinde 1956), two
separate lines of evidence suggest strongly that
territories contribute to the regulation of local
densities in warbler populations. Stewart and Aldrich (1951) and Hensley and Cope (1951)
removed adult birds from their territories in 1949 and 1950 respectively, in a 40 acre plot in a budworm infested area of Maine. The vacated territories were always filled by new pairs. the males singing the vigorous song of a bird setting up a
territory. It seems nearly inescapable that these
were part of a large floating population of birds
only prevented from breeding by the absence of
unoccupied .territories. Since this was in a bud
worm outbreak, there seems little doubt that there
would have been adequate food for a larger breed
ing population.