Figure 1.
Map of Sikkim showing sampling locations in different elevations.
Table 1.
Details of transects laid along the elevation gradient of Sikkim, Eastern Himalaya.
Figure 2.
Elevational distribution pattern of birds.
Elevational variation of bird species richness (observed and Chao 2), rarefied richness (rarefied to 260 individuals) and density (birds/ha) in Sikkim, Eastern Himalaya.
Figure 3.
Species accumulation curves of birds.
Curves based on number of individuals detected in different elevational transects in Sikkim, Eastern Himalaya. Numbers in the figures indicate elevation (m) of the sampling site.
Figure 4.
Scatter plot showing the relationship between elevation and vegetation parameters in Sikkim, Eastern Himalaya.
Figure 5.
Bird species richness curve (line with squares) along the elevation gradient of Sikkim, Eastern Himalaya with 95% simulation curves (lines without markers) obtained using empirical range sizes through the programme mid- domain null [30].
Table 2.
The r2 values and associated P-values for simple linear regression between observed species richness, Chao2 estimated richness, rarefied richness and density of birds as a measure of six environmental factors.
Table 3.
Result of stepwise multiple regressions with bird species richness and bird density as response variable and MDE predicted richness, AET, plant species richness, tree density, shrub density and BA of trees as predictor variable.
Figure 6.
Spatial correlograms for birds, AET and habitat variables along the elevation gradient of Sikkim, Eastern Himalaya.
Correlograms represents (A) observed bird species richness, (B) bird density, (C) mid-domain effect predicted richness, (D) actual evapotranspiration, (E) plant species richness, (F) tree density, (G) shrub density and (H) basal area of trees.
Figure 7.
Elevational range profiles of birds of Sikkim, Eastern Himalaya.
Vertical bars indicate maximum and minimum elevational limits of each species.
Figure 8.
Elevational range-size distribution of birds of Sikkim, Eastern Himalaya.