Table - link individuals/km^2
||Kevin J. Gaston & Tim M. Blackburn, How many birds are there? Biodiversity & Conservation, April 1997, Volume 6, Issue 4, pp 615–625 p.617 table 1
||Terborgh, J., Robinson, S.K., Parker III, T.A., Munn, C.A. and Pierpont, N. (1990) Structure and organization of an Amazonian forest bird community. Ecol. Monogr. 60, 213-38 link
||Abstract: "Here, [investigators] use a variety of methods to estimate the global number of individuals for a single taxon, birds." Primary source abstract: "To help fill the gap in detailed knowledge of avian community structure in tropical forests, [investigators] undertook a census of a 97—ha plot of floodplain forest in Amazonian Peru. The plot was censused over a 3—mo period spanning the 1982 breeding season. The cooperative venture entailed ≈12 person—months of effort. Conventional spot—mapping was the principal method used, but several additional methods were required to estimate the numbers of non—territorial and group—living species: direct counts of the members of mixed flocks, saturation mist—netting of the entire plot, opportunistic visual registrations at fruiting trees, determination of the average size of parrot flocks, color banding of colonial icterids, etc."
||P.617 bottom paragraph: "Instead, however, [investigators] consider the densities reported in just a single paper - that of Terborgh et al. (primary source) on the densities of forest birds. This paper summarizes estimates of the total number of individuals in a square kilometre of seven different forests from five continents (Table 1)." P.618 2nd paragraph: "To obtain estimates for the number of individual birds globally, [they] multiplied the square kilometre densities in Table 1 by estimates of total land area for the globe."