When density dependent events play a majo
role in regulating abundance, interspecific rela
tions are also important, for the presence of a
individual of another species may have some of th
effects of an individual of the original densit
dependent species. This is clearly illustrated b
the generalized habitats of the few species
passerine birds of Bermuda contrasted with thei
specialized habitats in continental North Americ
where many additional species are also presen
(Bourne 1957).