| Comments |
P.621 3rd paragraph: "The obvious inconsistency in estimates comes from applying Method II to the data from individual countries, which results in estimates almost an order of magnitude lower than any other method. However, this difference is unsurprising, given that all the countries for which [investigators] have data on the number of individual birds are north temperate (Table 2: Osborne and Tigar [1992] classify bird species in Lesotho [30,000 km^2] into logarithmic classes of population size, using the midpoint of these classes gives an estimate of 21,760,500 individual birds and a density of 725/km^2, which is a little higher than those figures in Table 2). Comparison of Tables 1 [BNID 116942] and 2 shows that the estimates of number of individuals per square kilometre are of similar orders of magnitude in all temperate locations, although the country estimates are still low. Inclusion of data from tropical countries would undoubtedly raise the country estimate considerably. The analyses for Method I indicate that most (around 70%) individual birds are tropical." |