International Journal of Molecular Evolution and Biodiversity 2016, Vol. 6, No. 1, 1-12
5
Table 3 Species similarity among the three habitats types in different seasons
Habitat
Season
Simpson’s similarity index (SI)
Wetland
Woodland
Riverine forest
Wetland
Wet
-
(0.11)
(0.08)
Dry
-
(0.14)
(0.15)
Both
-
(0.44)
(0.41)
Woodland
Wet
-
-
(0.44)
Dry
-
-
(0.31)
Both
-
-
(0.76)
Table 4 Abundance of avian species during the wet and dry seasons using encounter rates
Habitat
Season
Rank
Wetland
Rare
Uncommon
Frequent
Common
Abundant
Wet
-
20
16
5
-
Dry
-
23
16
8
1
Woodland
Wet
-
11
33
23
-
Dry
-
8
38
3
-
Riverine forest
Wet
-
7
9
15
2
Dry
-
20
15
11
1
4 Discussion
The difference in species diversity, number of species and number of individuals of species among the different
habitat types of the present study could be associated with differences in habitat characteristics and feeding habits
of birds as suggested by Smith (1992). Among the three studied habitats, the most diversified habitat in avian
species was the woodland (H’max= 4.47) followed by riverine forest (H’max =3.97). This variation could be due
to variation in habitat heterogeneity. The more heterogeneous vegetation and vegetation strata in the woodland
and riverine forest compared to the wetland could have provided several niches for birds making the woodland
and riverine forest with high diversity of birds. The importance of the availability of different vegetation strata for
different bird species is also supported by other studies. For example, Cueto and Casenava (1999) reported
positive correlation between bird species richness and the availability of vegetation strata. Similarly, Erdelen
(1984) indicated significant correlation between bird species diversity and vegetation structure. Chace et al. (2006)
reported that birds respond to changes in vegetation composition and structure, which in turn affects their food
resources.
The variations in species composition recorded during the wet and dry seasons were not significantly different.
This is in line with Shimelis and Bekele (2008) who reported the negligible effect of season or the role of climate
in affecting the diversity of birds of a particular habitat. Within the same habitat, the highest seasonal similarity of
bird species was observed in the wetland (SI=0.92). This might be due to the availability of similar and stable food
resources both in the wet and dry seasons in the wetland than the other two habitat types. The relatively small
seasonal similarity of bird species observed in woodland (SI=0.5) may be due to local migration of birds to the
riverine forest and wetland when resources are scare in the woodland as many bird species migrate thereby
optimizing availability of food sources and breeding habitats.
Among the three habitat types, more similarity of birds species was recorded from woodland and riverine forest
