Diversity of Woodland Song-Bird Populations

SUMMARY (1) Song-bird populations were censused by the mapping method and vegetation profiles were measured on eighteen plots in planted and semi-natural woodland in Scotland over 1-3 years. (2) The diversities of the song-bird communities were calculated using a standard formula; the complexity of vegetation structure on each plot was measured by the diversity of the distribution of foliage within a number of height ranges. (3) With an optimum choice of height ranges into which the vegetation profiles were divided, the correlation coefficient between bird species diversity and foliage height diversity was 0887. There were four height ranges: 0-0-6 m, 06-6.0 m, 6-15 m, > 15 m. (4) Use of numbers of song-bird species or total denisities in place of bird species diversity resulted in lower correlation coefficients. (5) The increase in bird species diversity with increase in foliage height diversity was seen as the result of the exploitation of an increased number of available niches. (6) The regression line between BSD and FHD could be used to predict BSD when FHD was known.