Bird Community Dynamics i Relation to Water Level Fluctuation in Koshi Tappu Wildlife Reserve
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Department of Zoology
Abstract
Land cover was classified using satellite image in to four classes. Supervised method of
classification was used to analyze change in microhabitat. Study area was classified into four
groups according to availability of water level, i.e. Land, Shallow water, Wet-Muddy flat,
Deep water. Wetland bird community was classified into four groups according to
morphological adaptation i.e. Swimmers, Waders, Shorelines and others (which do not fall in
above three categories). Wetland bird survey was conducted in four different seasons of
2018/2019. Bird survey was carried with continuous point transect method. A total of 1526
individuals of birds belonging to 53 species 17 families and 10 orders were recorded, among
them 15 species of swimmers, 20 species of waders, 9 species of shoreliners and 7 species of
others (river birds) were recorded. Pearson correlation test was used to establish the relation
between bird community and landscape classes. Highest water level was observed in summer
and lowest in autumn. Shannon diversity (H) was maximum of, 2.817 at intermediately
disturbed site and lowest at the most disturbed site of, 0.636 both in winter season. Tukey
HSD test, showed that bird community assemblage in summer and winter was significantly
different. Regression analysis revealed that as water level decreases diversity and abundance
of Waders increases. Canonical correlation analysis between bird and microhabitat showed
that, Waders prefer open water and Typha spp. Wet-muddy flat habitat was favored by most
of the species. Classification of microhabitat with remote sensing in each season showed that
landscape composition has changed significantly from summer to winter. Swimmers showed
significant positive correlation with Shallow water class (r=0.93). Shorelines also showed
significant positive correlation with shallow water class (r=0.94) and slight positive
correlation with wet muddy class (r=0.64) and with deep-water class (r=0.644) whereas
significant negative correlation(r=-0.93) with land class. Waders showed significant negative
correlation (r=-0.72) with deep-water class and shallow water class (r=-0.18) whereas
positive correlation with wet-muddy and slight positive correlation(r=0.07), with land waders
showed high correlation(r=0.06) with wet-muddy class. The study revealed that bird
composition (NMDS F = 3.10; p < 0.0001, Stress value=0.14) was significantly different in
four different seasons. This study suggests that water level fluctuations is one of the major
factors, which influences the abundance, and composition of Wetland dependent birds.