Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 December 2023 | 15(12): 24331–24344
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.8357.15.12.24331-24344
#8357 | Received 06 January 2023 | Final received 16 October 2023 |
Finally accepted 08 December 2023
Assessing and understanding
diversity and foraging guilds of bird community structure in Gautam Buddha
Wildlife Sanctuary, Bihar and Jharkhand, India
Umar Saeed 1, Mujahid Ahamad 2, Vivek Ranjan
3, Syed Ainul Hussain 4 & Ruchi Badola 5
1–5 Department of Eco-Development
Planning and Participatory Management, Wildlife Institute of India, Dehradun, Uttrakhand 248001, India.
1 umar2673@gmail.com, 2 syedmujahidahmad@gmail.com
(corresponding author), 3 vivek.nil@gmail.com, 4 ainul.hussain@gmail.com,
5 ruchi@wii.gov.in
Editor: H. Byju,
Coimbatore, Tamil Nadu, India. Date of publication: 26 December
2023 (online & print)
Citation: Saeed, U., M. Ahamad, V. Ranjan, S.A. Hussain
& R. Badola (2023). Assessing and
understanding diversity and foraging guilds of bird community structure in
Gautam Buddha Wildlife Sanctuary, Bihar and Jharkhand, India. Journal of Threatened Taxa 15(12): 24331–24344. https://doi.org/10.11609/jott.8357.15.12.24331-24344
Copyright: © Saeed et al. 2023. Creative Commons Attribution 4.0 International
License. JoTT
allows unrestricted use, reproduction, and distribution of this article in any
medium by providing adequate credit to the author(s) and the source of
publication.
Funding: The study is funded by the Dedicated Freight Corridor Corporation of India
Limited (DFCCIL) [Permission no. CPM/DFCCIL/KKK wildlife – 186 dated 22 December 2015].
Competing interests: The authors declare no competing interests.
Author details: Umar Saeed is a
senior research fellow at the Wildlife Institute of India and currently pursuing PhD from Graphic Era University and perceives a field of interest in grassland management and conservation ecology. Mujahid Ahamad is a
PhD scholar and currently working as a senior project biologist at the Wildlife Institute of India, Dehradun. He specialized in animal ecology and human-wildlife interaction. Vivek Ranjan is a
PhD scholar at the Wildlife Institute of India working on human-wildlife interaction in human-dominated landscapes. He has been actively supporting Uttarakhand State Forest Department in the management and mitigation of negative human-wildlife interaction and encouraging coexistence through technical advisory. Syed Ainul Hussain is the project manager (NMCG) and former scientist-G at the Wildlife Institute of India. Ruchi Badola is dean and scientist-G at the Wildlife Institute of
India.
Author contributions: US—conceptualization, data collection, data analysis & visualization, methodology, writing the original draft. MA—conceptualization, writing original draft, data collection. VR—data collection. SAH—conceptualization, funding acquisition, investigation, supervision, writing - review & editing.
RB—conceptualization, writing - review & editing.
Acknowledgements:
We express our thanks for the financial support from the DFCCIL
(Dedicated Freight Corridors Corporation Limited) for this study. The study permission
no. CPM/DFCCIL/KKK wildlife – 186 dated 22 December 2015. We take this
opportunity to express a deep sense of gratitude for the constant support
received from Mr. A.K. Dwivedi CF, Gaya forest circle, and Mr. Arvind Kumar
Singh DFO Gaya forest circle (Environment and Forests Department, Government of
Bihar) and D.K. Yadav Singh DFO Hazaribagh forest division Jharkhand for
providing the necessary support during the fieldwork and assure the good
environment around us. We also thank our colleagues Rashmi Das and Kumar Ankit
for their valuable suggestions and comments for the improvement of the
Manuscript.
Abstract: This study was conducted between
June 2017 and December 2018 to assess the bird community structure, diversity,
feeding guilds, and the residential status of birds in Gautam Buddha Wildlife
Sanctuary (GBWS). Avian diversity and
guild organization in five different habitat types were classified according to
the forest type present in the landscape. The results indicated a total of 99
avifauna that belongs to 48 families, distributed in 16 orders. Among the 99
species, 77 were residents, 17 were winter visitors, four were summer visitors,
and only one was a passage migrant. Based on the feeding guild evaluation, the
majority were insectivorous (47%), followed by omnivorous (24%), carnivorous
(14%), granivorous (8%), frugivorous (4%), insectivorous (1%), and piscivorous
(1%). The scrubland, among other forest types, represented the highest
diversity value for the Shannon-Weiner diversity index (3.2), evenness was
recorded highest in riverine habitat (0.63), whereas utmost Simpson’s dominance
(0.98) and Fisher’s index value (41) were in human settlement. These findings
of our study illustrate the outstanding potential of GBWS as an important
protected site for mixed bird diversity and specific feeding guilds, precisely
in terms of the insectivorous and omnivorous communities. Hence, the study
outcomes set a notable landmark for understanding birds and their habitats.
Keywords: Avifauna, evenness, Fisher’s
index, habitat types, protected site, residential status, Simpson’s dominance,
Shannon-Weiner diversity index.
Introduction
Bird communities are considered
to provide excellent model structures for studying biodiversity due to their
occurrence in all habitat types and climatic zones (McCain & Grytnes 2010; Panda et al. 2021). Mixed habitats such as
woodland, cropland, scrubland, riverine, and grasslands ensure the existence of
habitat-restricted taxa and amplify community diversity (Berg 2002; Stein et
al. 2014; Stein & Kreft 2015). Additionally, the
diverse characteristics within natural environments and species diversity are
pivotal in upholding essential traits that contribute significantly to biodiversity.
(Manhães & Loures-Ribeiro
2005). Species diversity and richness in a particular area are determined by
habitat heterogeneity and may also impact habitat resources (Lorenzón et al. 2016). At the same time, the absence of a
natural environment leads to species homogenization with low species richness
(Pickett et al. 2011; Lepczyk & Warren 2012;
Aronson et al. 2014; Beninde et al. 2015) and high
similarity (Blair 2001a,b). Bird diversity is always
correlated with specific habitat types (Brawn et al. 2001; Seymour &
Simmons 2008; Harisha & Hosetti
2009). Changes in their vegetation structure are affected by bird community
structure and composition (Caziani & Derlindati 2000; Gabbe 2002; Earnst & Holmes 2012; Nsor et
al. 2018), population trends, behaviour patterns, and
reproductive ability (Harisha & Hosetti 2009). Vegetation structure is essential in
structuring bird communities (Gabbe et al. 2002; Earnst & Holmes 2012); thus, the relative abundance of
birds is often linked to vegetation community (Caziani
& Derlindati 2000). For example, MacArthur &
MacArthur (1961) pointed out the importance of vegetation structure for local
bird species diversity. Williams (1964) highlighted that various environmental
conditions and habitat types increase with an increase in the study area.
Feeding guild is a fundamental
concept in avian ecology and is shaped when a community of birds uses the same
class of environmental resources (Balestrieri et al.
2015). Katuwal et al. (2016) stated that all guilds
have different resource requirements and tolerance capacities depending on
ecological conditions, which are influenced by various environmental factors
such as vegetation cover, food supply, predatory availability, and various
other ecological factors reflecting different temporal variations and diversity
gradients (O’Connell et al. 2000; Kissling et al. 2012). Studies of avian
feeding guilds help to understand complex ecosystem structures and improve
knowledge about the habitats of a particular ecosystem (Rathod & Padate 2017).
The distribution and feeding
guild of the birds is associated with their habitat type and structural
complexity, which influence species diversity and the inter-relationship
between vegetation and the avian population (MacArthur & MacArthur 1961). Many
studies have been conducted to determine relationships between bird species
diversity and habitat attributes such as heterogeneity and vegetation structure
(Chettri et al. 2005; Corbett 2006; Yeany 2009;
Beasley 2013; Stirnemann et al. 2015). Bird populations
in fragmented landscapes respond resiliently to complex environmental
combinations and are an indicator of habitat change, and they also show a wide
range of feeding guilds (Azman et al. 2011). Protected areas with substantial
anthropogenic disturbance causes habitat fragmentation
and degradation (Haddad et al. 2015; Wilson et al. 2016; Pardini
et al. 2017).
In the Gautam Buddha Wildlife
Sanctuary (GBWS), over the past few years, the widening of the National Highway
(NH-2) has split the sanctuary into two halves. Moreover, anthropogenic
pressures, selective hunting, and the expansion of villages in and around the
sanctuary have been significant causes of biodiversity decline (Kumar 2016).
The study of bird diversity and feeding guilds is crucial for understanding the
complexity of ecosystem structure and for providing up-to-date knowledge on
each habitat type in the ecosystem. In addition, we have also assessed the
abundance of birds in the various habitat types. Thus, the present study aimed
to understand the diversity of birds and feeding guilds with different habitat
types, such as woodland, scrubland, human settlement, riverine, and cultivation
lands. The study will also provide baseline information on the bird community’s
species richness, which will help design management plans and conservation
strategies for the sanctuary.
Study area
The GBWS lies between 24.379°–24.425° N and 85.136°–85.213°
E and is situated in the southeast part of the sacred city of Gaya district,
Bihar. The sanctuary spreads over an area of 259.47 km2 in the
states of Bihar and Jharkhand under three forest divisions: the Gaya Forest
Division (138.33 km2) in Bihar and the Hazaribagh and Chatra Forest Division (121.24 km2) in Jharkhand
(Figure 1). The Bihar government notified the sanctuary in 1976. Before
becoming a sanctuary, it used to be the hunting ground of the Tikri king. The terrain of the sanctuary is undulating,
with an elevation ranging 213–529 m. The sanctuary is drained by the perennial
river Mohane, a sink for all the streams and rivulets
flowing in the sanctuary (Kumar 2016). The south-west monsoon starts in June
and lasts until September. Rainfall is highest between June and July, with an
average rainfall of 159 mm. The average temperature varies 26–90C
during the winter season, which commences from November to February (Nirbhay & Singh 2009). The average summer temperature
ranges around 400C maximum, even touching 470C, and is
usually characterized by dry and hot weather conditions from March to June.
The sanctuary falls in the lower
Gangetic Plains and Chota Nagpur biogeographical
regions of India and shares wildlife species from both regions. Making it a
unique ecosystem that supports a wide diversity of floral and faunal species
(Rodgers & Panwar 1988; Kumar 2016; Kumar et al. 2021). The sanctuary is
characterized by moist and dry deciduous forests (Kumar et al. 2021). Forest
communities are further divided into dry peninsular sal
forest, northern dry mixed deciduous forest, dry deciduous scrub forest, ravine
thorn forest, and tropical dry riverine forest (Kumar 2016; Kumar & Sahu 2020). More than 100 species of plants and 75 species
of birds enrich the biodiversity of the sanctuary (Kumar et al. 2021). Various
dominant flora of the sanctuary comprises Shorea
robusta, Pterocarpus
marsupium, Diospyros melanoxylon,
Lagerstroemia parviflora, Buchanania
lanzan, Butea monosperma,
Madhuca indica,
Acacia catechu, and Boswellia serrata. It also supports various wild animal species,
such as Axis axis, Rusa
unicolor, Melursus ursinus,
Boselaphus tragocamelus,
Vulpes bengalensis, and Felis chaus, among others
(Kumar 2016).
Methods
and Materials
Data collection
The avifaunal status, habitat
characteristics, and community structure were assessed using the point count transect
method during summer (June–August 2017) and winter (November–December 2018).
Bird observations occurred from 0700 h to 1000 h, avoiding adverse weather
conditions (Ding et al. 2019). A 1-km trail transect with five observation
points at 250 m intervals was used, involving two observers. Within a 50-m
radius during a 15-minute duration, bird species, distances, and individual
numbers were recorded. Birds flying overhead of the observer were not recorded
to avoid the double count. The birds were observed with the help of Nikon
(8x10) binoculars, and photographs were taken using a Cannon 80D camera for
further identification. The birds were identified with the help of Grimmett et al. (2016).
Guild classification
In this study, birds were
systematically categorized into distinct feeding guilds based on their primary
diet and foraging habitats, following the classification outlined by Ding et
al. (2019) and Panda et al. (2021). The seven identified guild categories are
as follows: insectivores (species consuming insects, earthworms, small
crustaceans, and arthropods), carnivores (species preying on large animals or
scavenging their carcasses), omnivores (species with a mixed diet of both
animals and plants), granivores (species primarily
feeding on seeds and grains), nectarivores (species relying on nectar as a
primary food source), frugivores (species mainly consuming fruits), and
piscivores (species specialized in a fish-based diet). This classification
scheme provides a comprehensive framework for understanding the diverse dietary
preferences and foraging behaviors exhibited by avian species within the
studied ecosystem.
Data analysis
In the data analysis phase,
various species diversity indices were computed using the Paleontological
Statistics (Past 2001 version 3.2) program (Hammer & Harper 2001).
Shannon’s diversity index (H) was employed to assess community diversity,
calculated using the formula H = -∑(pi ln pi), where
pi represents the proportion of individuals of a particular species with the
total number of individuals (n/N), and s is the
number of species. Simpson’s index (D), a dominance measure, was also utilized,
given by the formula 1/(∑(pi^2)), where pi is as defined for Shannon’s index.
Fisher alpha (S) was employed to mathematically describe the relationship
between species and individuals, expressed as S = α × ln(1
+ n/a), with S denoting the number of taxa, n representing the number of
individuals, and α as Fisher’s alpha (Fisher & Yates 1953). Evenness
(e), comparing actual diversity to maximum potential diversity, was determined
using e = H’/H_max, with E constrained between 0 and
1. Relative abundance (RA) of each bird species was calculated as ni/N × 100, with ni being the
number of individuals of the ith species and N being
the total number of individuals. Abundance categories were assigned based on
sightings, from rare (1–5) to very abundant (>50). The Sorensen similarity
index (Cs) gauged species association between habitats using Cs = 2j/(a + b), where j is the number of common species, a is the
number of species in habitat A, and b is the number of species in habitat B.
Bird residential status categories (resident, summer visitor, winter visitor
influx) were determined using the presence and absence method (Sorensen 1948).
Statistical analyses were conducted in SPSS, with significance at p = 0.01.
Pearson’s correlation (r) explored relationships between guilds, residential
status, and habitat types, and post-hoc Wald tests with Bonferroni adjustments
were performed for identified significant differences. Additionally, a one-way
analysis of variance (ANOVA) examined significant differences in
habitat-related species richness concerning feeding guilds and residential
status.
ResultS
The present study recorded 99
avifaunal species belonging to 16 orders and 48 families in GBWS. Amongst the
habitats, the highest species richness was recorded in woodland (53.52%), and
the lowest species richness was recorded in cultivation land (20.20%) (Table
1). The highest number of species belongs to the order Passeriformes (52.52%),
followed by Accipitriformes and Charadriiformes
(Figure 2). The species diversity of birds in five different habitats of the
study area revealed that the highest Shannon diversity was recorded in
scrubland (H = 3.186), followed by woodland (H = 3.181) and human settlement (H
= 3.136). In contrast, the lowest Shannon diversity was recorded in cultivation
land (H = 2.527). The Simpson diversity index value was maximum in human
settlement (1-D = 0.978) and minimum in woodland (1-D = 0.926). The Evenness of
bird species was highest in the riverine (0.629) and lowest in the woodland
forest (0.454) (Table 1). At a 95% confidence interval level, we found that
scrubland possesses the highest holding capacity of diversity compared to the
other habitats. The Fisher alpha diversity index was highest in human
settlement (α = 41.12). The lowest Fisher alpha diversity profile was recorded
in cultivation land (α = 16.47) (Figure 3).
According to the frequency of
sightings, 68.68% of bird species were rare, and 1.01% were abundant in GBWS
(Figure 4). The relative abundance of Red-vented Bulbul Pycnonotus
cafer was highest in the study area, followed by
Jungle Babbler Turdoides striata and Grey-breasted Prinia
Prinia hodgsonii
(Appendix 1). Results of Sorenson’s similarity index indicate that woodland and
scrubland (0.31) were ecologically the most similar habitats, followed by the
similarity between woodland and human settlement (0.30). However, riverine and
woodland had the most negligible ecological similarity value (0.14) (Table 3).
Further, the bird species were
categorized according to their feeding guild. Among the feeding guilds, the
insectivorous guild recorded a maximum percentage of species (47.47%), and
nectarivores and piscivorous guild recorded a minimum percentage of species
(1.01%) (Figure 5). Regardless of the habitats, the dominant guild remained the
insectivorous among all the guilds. The comparison of the abundance of species
from all habitats within every feeding guild is shown in Table 2.
The Pearson correlation
coefficient provided visions of the specific preference of the bird species
under different foraging guild towards some particular habitats. The
frugivorous guild was most positively correlated with human settlement (r =
0.282, t = 0.320 p < 0.01), and negatively with cultivation (r = -0.29, t =
1.988, p >0.01), riverine (r = -0.102, t = 2.267, p >0.01), and scrubland
(r = -0.045, t = 2.021, p >0.01). Insectivorous bird species were only
positively correlated with the riverine habitat (r = 0.127, t = 8.037 p
<0.01) and negatively correlated with the remaining habitats. Omnivores were
most positively correlated with scrubland habitat (r = 0.156, t = 4.459 p
<0.01) and a negative correlation with riverine habitat (r = -0.150, t =
1.9885, p <0.01). On the other hand, the carnivorous guild was strongly
associated with cultivation habitat (r = 0.128, t = 3.295 p <0.01). Granivores showed a positive association with only
scrubland habitat (r = 0.105, t = 2.038 p <0.01).
Further, the residential status
of the species revealed that 77 birds were residents, whereas the remaining 17
were winter visitors, four were summer visitors, and one species was a passage
migrant (Figure 6). While analyzing the association of different habitats
according to their residential status, we found that resident bird species were
positively correlated with all the habitat types, but the association was
highest with scrubland (r = 0.177, t = 16.226 p <0.01). It was discovered
that there was no significant correlation between any of the habitat categories
and summer visitors, winter visitors, or passage migrants.
Discussion
The bird diversity and their
distribution concerning habitat types characterize the importance of GBWS as an
essential bird habitat. The present study revealed that Passeriformes was the
dominant order comprising the highest number of bird species. Two species
represented the order Bucerotiformes and Piciformes; besides the order Ciconiiformes,
Falconiformes, Gruiformes, Podicipediformes, and Strigiformes
were represented by single species. This study agrees with the prior result
that order Passeriformes is the leading avian taxon in India (Praveen et al.
2016; Kumar & Sahu 2020; Singh 2022). Data
analysis on relative abundance shows that the Accipitridae
family is the most dominant one. A similar pattern of dominance of Accipitridae was recorded by different authors from
different protected areas in India, for example, from the Araku Valley of Ananthagiri Hills
of the Eastern Ghats in Visakhapatnam, Andhra Pradesh (Kumar et al. 2010), a
scrub forest of Sri Lankamalleswara Wildlife
Sanctuary, Andhra Pradesh (Mali et al. 2017), Tamhini
Wildlife Sanctuary, the northern Western Ghats, Maharashtra (Vinayak & Mali
2018), and Bhimbandh Wildlife Sanctuary, Bihar (Khan
& Pant 2017).
The GBWS comprises a mosaic
habitat, which supports a significant diversity of bird species. Habitat
heterogeneity favors habitat specialists (through niche partitioning) for birds
with broad niches (Surasinghe et al. 2010; Chakdar et al. 2016). The overall Shannon diversity index
(H = 3.935) of GBWS is high. Therefore, the Shannon diversity in all habitats
was good except in cultivation land (H = 2.527). The habitat heterogeneity
hypothesis suggests that a landscape’s species diversity increases with the
number of habitats because of an expansion in the number of partitionable niche
dimensions (Cramer & Willing 2005; Chakdar et al.
2016). Numerous studies have revealed that the distribution and diversities of
bird species were highly dependent on habitat heterogeneity (Hettiarachchi & Wijesundara
2017; Chandrasiri et al. 2018; Panda et al. 2021; Thilakarathne et al. 2021).
As the Simpson diversity index
has swift convergence to limit diversity value for a minor sample size, it is
principally suitable for rapidly estimating regions for conservation (Lande et al. 2000). Analysis of data on the Simpson
dominance index revealed that human settlement (1-D = 0.978) was the most
dominated habitat in the sanctuary followed by riverine habitat (1-D = 0.960).
The high value of Simpson’s index of diversity is an indication of the richness
of bird diversity in the GBWS. The result revealed that bird species’ Evenness
varied in the sanctuary’s different habitats. The highest evenness index value
was recorded in the riverine habitat. Several reasons, including food
availability, breeding, migration, and change in vegetation cover, could be
attributed to this pattern (Harisha & Hosetti 2009). However, the lowest evenness index value recorded
in woodland habitat expresses that the species-rich site may result from the
occurrence of rare species or two or three species being hyper-abundant in the
area compared to the other sites (Symonds & Johnson 2008).
However, the Fisher alpha diversity
index was highest in human settlement (α = 41.12), as the number of individuals
was low compared to the species number. In woodland habitats, the species
diversity is highest, but due to the presence of more individuals of the bird
species, Fisher’s alpha was lower (α = 17.26) than in human settlement. The
lowest Fisher alpha diversity profile was recorded in cultivation land (α =
16.47) (Figure 3). The diversity, which compares the similarity between
habitats, is measured by Sorensen’s similarity index between the five selected
habitats. The result revealed that woodland and scrubland had the highest
similarity value (0.31), while the lowest species similarity (0.14) was
recorded between woodland and riverine habitats. The highest value of
Sorensen’s similarity indices documented between woodland and scrubland
habitats might be attributed to landscape characteristics. Better habitat
structural similarity tended to support more similar bird communities (Tubelis & Cavalcanti 2001; Andrade et al. 2018; Kumar
& Sahu 2020).
Correlation values between
different feeding guilds and habitat preferences displayed that the frugivorous
bird population flourished well in the area with human settlement due to the
sufficient availability of food sources. Gomes et al. (2008) have shown that
resilient frugivores that increased in densities have occurred under all
habitat disturbance regimes of the forest area, which markedly supports our
study. In another study (Pejchar et al. 2008),
frugivore abundance and richness were found to strongly account for a positive
relationship with the human-dominated landscape. These results account for the
fact that frugivores can tolerate moderate to intermediate levels of
disturbance.
The significant positive
correlation of insectivores was highest with riverine habitat. Other studies
supporting the observation state that in wetlands, aquatic insects classically
dominate the macroinvertebrate communities (Maher 1984; Euliss
& Grodhaus 1987; Batzer
& Resh 1992; Mukhopadhyay & Mazumdar 2019) and
are an integral part of various aquatic ecosystems (Sivaramakrishnan
et al. 2000). Omnivores and granivores were most
favorable and significantly correlated with the scrubland habitat due to the
mosaic structure of the habitat of GBWS. This contrasts with the findings of
Mukhopadhyay & Mazumdar (2019), in a suburban landscape of the lower
Gangetic plains of West Bengal, where the omnivores mostly dominated the
residential and plantation forest area. Panda (2021) has also found a
significant close association between human habitation with omnivores.
Additionally, granivores
are positively related to the scrubland area, Poulin et al. (1993), support and
validate our outcomes as they found a peak number of granivores
interactions in the scrubland of the Guarapo region
on the Araya Peninsula. In contrast, other studies support the preference of granivores for low-stratification crops (Henderson et al.
2000) and the positive relation with orchards due to the protection these areas
offer from predation by birds of prey (Figueroa & Corales
2005). Furthermore, our study revealed that carnivorous species were primarily
observed in cultivated forest areas due to the enormous presence of small size
of frogs, fishes, molluscs, and small vertebrate
species. Likewise, Tanalgo et al. (2015) agree with
our study that carnivorous species were primarily observed in the rice fields.
Stafford et al. (2010) indicated that the abundance of carnivorous bird species
in rice fields is due to the availability of a large number of food resources,
such as polychaetes, crustaceans, and molluscs. Besides, King et al. (2010) also noted that the
rice fields in many countries support large numbers of migratory water birds
and are essential for many species.
A significant positive correlation
of the resident bird species with all the habitat types shows that these
species are well distributed in the GBWS, but they mostly prefer the scrubland
area. A study by Daily et al. (2001) also suggests that bird species mainly
were correlated with the forest fragments. The migratory bird species do not
possess any significant positive correlation with the different habitats. This
is because migrants distribute themselves spatially and temporally relative to
available fruit resources at different intervals (Wolfe et al. 2014).
Moreover, human interference and
livestock pressure significantly threatened bird species in the sanctuary
(Image 1,2). The presence of livestock in bird habitats caused a significant
negative impact on the abundance and species richness of bird species (r =
-0.308, p = <0.01). After agriculture, local inhabitants also depend on the
sanctuary for livestock grazing. Overgrazing led to the destruction of plant
seedlings and restricted forest regeneration. Studies by Adhikari et al. (2019)
support our finding as they have also found that livestock pressure and human
disturbances were the major threats to birds in Chitwan National Park. The
presence of local people in the forested land caused a non-significant negative
impact on bird species richness and abundance in the sanctuary (r = -0.091, p =
>0.01). Another major cause of disturbance in bird habitat is the cutting of
trees for fodder and fuelwood collection (Image 3). The Pearson correlation
coefficient value of tree cutting was negatively not significant to habitat (r
= -0.064, p = >0.01). These pragmatic findings suggest a negative impact of
livestock and human interference on the bird species richness and abundance.
Conclusion
The present study is the first
documentation of the bird diversity, richness, and feeding guilds found in
GBWS. Our study concludes with evidence that GBWS is an essential habitat for
birds with high conservation status.
The diversity of bird species
recorded is highest in the scrubland habitat and lowest in the cultivation
habitat. However, these habitats are under constant threat of high risk for
immense anthropogenic pressure. Also, if human disturbance increases at the
same pace, there would be the threat of homogenization of avian species, as
these generalist species have the advantage over the specialists in disturbed
ecosystems. Consequently, the study suggests that maintaining heterogeneous
habitats could be a better strategy for the long-term survival of resident and
migratory birds in GBWS.
Table 1. Percentage,
feeding guild, diversity, and dominance of birds in different habitats in GBWS
Bihar and Jharkhand.
|
|
Habitat |
Number of species |
Percentage |
Feeding guild |
Shannon diversity |
Simpson (1-D) |
Evenness |
Fisher alpha |
|
1 |
Woodland |
53 |
53.53 |
6 |
3.181 |
0.926 |
0.454 |
17.26 |
|
2 |
Scrubland |
47 |
47.47 |
7 |
3.186 |
0.950 |
0.514 |
24.83 |
|
3 |
Riverine |
32 |
32.32 |
5 |
3.003 |
0.960 |
0.629 |
19.77 |
|
4 |
Human settlement |
37 |
37.37 |
6 |
3.136 |
0.978 |
0.621 |
41.12 |
|
5 |
Cultivation land |
20 |
20.20 |
5 |
2.527 |
0.947 |
0.625 |
16.47 |
Table 2. Species
presence at all habitats of each feeding guild.
|
Feeding guild |
Habitat |
Number of species |
||||
|
WL |
RV |
H |
CL |
SL |
||
|
Carnivorous |
7 |
5 |
3 |
4 |
3 |
15 |
|
Frugivorous |
4 |
0 |
2 |
1 |
2 |
4 |
|
Granivorous |
3 |
1 |
3 |
0 |
6 |
7 |
|
Insectivorous |
27 |
20 |
16 |
9 |
19 |
47 |
|
Nectivorous |
1 |
0 |
1 |
1 |
1 |
1 |
|
Omnivorous |
11 |
5 |
12 |
5 |
15 |
24 |
|
Piscivorous |
0 |
1 |
0 |
0 |
1 |
1 |
|
Number of species |
53 |
32 |
37 |
20 |
47 |
|
WL—woodland
| CL—cultivation land | RV—riverine | HS—human settlement | SL—scrubland.
Table 3. Sorenson’s
similarity index value between different habitats.
|
|
Habitat |
WL |
CL |
RV |
HS |
SL |
|
1 |
SL |
0.31 |
0.22 |
0.17 |
0.26 |
|
|
2 |
HS |
0.30 |
0.17 |
0.20 |
|
|
|
3 |
WB |
0.14 |
0.21 |
|
|
|
|
4 |
RV |
0.21 |
|
|
|
|
|
5 |
WL |
|
|
|
|
|
WL—woodland
| CL—cultivation land | RV—riverine | HS—human settlement | SL—scrubland.
For
figures, images & Appendix - - click here for full PDF
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