PATTERNS OF BIRD SPECIES DIVERSITY REVEALED BY CHRISTMAS COUNTS VERSUS BREEDING BIRD SURVEYS

Abstract

Continent-wide patterns of avian species diversity have been the subject of much recent attention, especially in comprehensive studies by Cook (1969) and Tramer (1974a). The objective of these and similar studies is to determine what factors of earth history, climate, vegetation structure, resource availability, and population interaction conspire to limit the number of bird species occupying a given region at a given time (see MacArthur 1965, 1972, and Tramer, op. cit., for reviews).