Introduction
Habitat fragmentation is one of the
major issues faced by biodiversity. Urban expansion is a major driver of global environmental change (Grimm et
al. 2008) Urban green patches
accounts for major
share of the total
urban diversity. Green areas in cities
are essential for biodiversity conservation because they constitute refuges
that enable certain native taxa to persist
in urban environments (Grimm et al. 2008; Sukhdev
2013; Nielsen et al. 2014). Thus, conserving and providing additional
green areas is an efficient method to improve both human wellbeing and
biodiversity conservation in cities (Miller 2002). This makes the urban patches
of supreme importance. This study deals the avian diversity of Kerala
University Campus Kariavattom.
Importance
of Urban Ecosystems
From an ecological perspective, urban
ecosystems are highly dynamic (Gilbert, 1989; Adams, 1994) and can provide
useful insights into the management of biodiversity
in other ecosystems. Urban ecosystems hold a good amount of diversity. Urban green areas are generally surrounded by built-upareas, and hence can be regarded as habitat-islands—relatively isolated habitats
in which biological interactions between
green areas are reduced by matrices dominated by
impervious surfaces (Tjørve and Turner 2009; Szlavecz et al. 2011;
Matthews 2015; Fattorini et al. 2018a). Thus, these areas can be analysed on
the basis of island biogeography concepts. For example, birds in urban green areas have been shown to follow
the general pattern
of increasing species richness with increasing island
area, i.e. they are characterized by positive species-area relationships
(‘SAR’; Fernández-Juricic and Jokimäki 2001; Beninde et al. 2015). The species
area relations in urban ecosystems are least explored. Not only areas but the floral
diversity of the area is very important when studying about the faunal diversity.
Fragmentation of habitat limits
dispersal and colonisation even in species as mobile as birds. (Greenwood PJ
1980). Some forest specific birds are not capable of crossing open areas
between woodlands. Also, the birds of urban ecosystems are
directly exposed to anthropogenic disturbances. This can
have negative impact on the fauna of the particular area. Studies conducted in protected areas demonstrate that human
presence can disturb bird species, with negative effects at the individual,
population and community levels (Skagen et al. 1991). Tolerance to human
activities affect birds in several aspects. Complexity of ecosystem can
increase tolerance to humans as this can reduce
direct interactions. Birds
show more tolerance
to people since they have more available cover to
hide from visitors (Knight and Temple 1995). Generally, species vary in
tolerance levels; large species seem less tolerant of humans than small
ones (Cooke 1980).
Migratory birds seem to be less tolerant
towards humans. Bird tolerance
can be estimated by flush distance, the distance at which a species escapes from a visitor;
the larger the flush distance,
the less the tolerance (Cooke
1980, Humphrey et al. 1987, Gutzwiller et al. 1998). Considering these
factors, we can find a positive
corelation between area, complexity of ecosystem
and bird diversity.
In urban ecology, cities and urbanized
areas are understood to be complex human-dominated ecosystems (Pickett et al.,
1997). Urban ecosystems are one of the most
disturbed ecosystems in the planet.
This also cause several problems
related to the ecosystem services. In urban
ecosystems loss of diversity can have impacts like increased chances
of spreading of diseases to issues related
to pests like mosquitos, rats, dogs etc. which are naturally in a controlled manner. In a natural ecosystem the number of
individuals is kept in check by the prey are predator relationships. Removal of multiple species from a food chain can
cause the multiplication of its prey populations. Also, urban ecosystems
generate huge amount of wastes which act as positive enforcement for the colonizing species like dogs and rats.
Proper management of urban
diversity can in turn have positives impact
on humans as well. The proper management can reduce the colonization of
nuisance species and also reduce chances of spreading of diseases and improve
overall hygiene of the city.
Biodiversity has different meanings to
biologists, to policymakers, and to the public. Biologically, the term applies
to many levels of biological organization (Noss 1990). All these notions have
to be taken into consideration while making a protection plan for urban
ecosystems.
Birds are of great economic importance
to humans. They are involved in pest control, scavenging, pollination and seed
dispersal etc. Birds play very crucial role in several ecosystems. They come in
the top of several terrestrial as
well as wetland ecosystems, thus controlling the entire ecosystem by up down regulation. Birds
are very sensitive to environmental changes
and are used as a “bio-indicator” (Koli,
2014); also, because of their
high mobility, birds react very rapidly to changes
in their habitats (Morrisson 1986; Fuller et al. 1995). Thus, birds can be
considered as typical indicator species which can show the variations as well as stability of an ecosystem. Thus, a good bird diversity can indicate
diversity of the ecosystem itself.
Threats
Faced by Avian Diversity
A wide range of substances/agents are
released into the environment due to anthropogenic activities. Higher levels of
such entities result in effects that reduce the
quality of the biosphere (Morrison 1986). Urbanisation is one of the fastest growing land use changes, with consequential impacts
on biodiversity (extinction, speciation and
distribution) across taxa. (McKinney ML. 2006). In general, the ambient
environment is negatively affected by the harmful effects of four major
problems arising due to the emission of substances/agents from human activities; air pollution, light pollution, noise pollution and global
warming/climate change. With regard to the latter, birds and amphibians are the
most threatened animal groups (Foden et al. 2013; Bird Life International
2013). Birds have narrow lung capillaries and higher breathing rates and spend
considerable amount of time in open air. Hence, they are highly vulnerable to
atmospheric particulate matter. Ground-level ozone and nitrogen oxides also
lead to negative effects on avian lungs (e.g. inflammation and lung failure).
In addition, these pollutants can also rupture of blood vessels upon long-term
exposure (Qin 2015). Increased human interventions in urban ecosystems spike
the pollution levels which in turn impose negative effects on birds. Due to
these increased anthropogenic activities urban green patches finds supreme
importance.
Classification of Birds
Based on fossil and biological evidence, most scientists
accept that birds are a specialised subgroup of theropod dinosaurs.(Prum 2008).
Birds are a group of warm- blooded vertebrates constituting the class Aves,
characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic
rate, a four-chambered heart, and a strong yet lightweight skeleton. The
passerines (perching birds) alone account for well over 5,000 species. In total
there are about 10,000 species of birds described worldwide, though one
estimate of the real number places it at almost twice that. (Barrowclough
et.al. 2016) The India Checklist acknowledges a total of 1263 species of birds for India. (Alström
et al. 2016). Taxonomically, it covers 23 orders, 107 families, and 498 genera, representing
the global avian diversity by about 64%, 45%, and 21% respectively.
Predictably, passerines (Order Passeriformes) form the most predominant group
(c. 54%), followed by the orders Charadriiformes (c. 10%), and Accipitriformes
(c. 5%). The State of Kerala has 500
species of birds, 17 of which are
endemic to Western Ghats, and 24 species fall under the various threatened
categories of IUCN( J Praveen et.al 2016).
Relevance of Kariavattom Campus
In this study the diversity of avian
fauna of Kerala University Campus Kariavattom was studies over a span of one
year. Kerala University Campus is located in the Trivandrum district (Kerala,
India 8°30′12″N 76°56′50″E). The University campus has an area of 359 acres of land out of which 60% of land still
remain as forests. In this particular scenario the
adjacent forests are around 30km from this green island. Which is a
comparatively lower distance when compared to the migrating abilities of birds.
Thus, the diversity of birds can be high as this can be considered as a near
and large isolated island based of island biogeography. Birds in urban green areas have been shown to follow the general pattern
of increasing species
richness with increasing island area,i.e. they are characterized by positive
species-area relationships (‘SAR’; Fernández-Juricic and Jokimäki 2001).
Study
Area
This study was conducted at Kerala
University Campus Kariavattom. (Kerala, India
8°30′12″N 76°56′50″E). The campus has an area of 352 acres and around 60% of
which is covered by thick vegetation. The entire area is cut into two by the
national highway. The two areas are named as North Campus and South Campus.
Four sites were selected in the campus based on habitat characters. These
habitats had different biogeographical characteristics. The study sites are
listed below;
Site
1- South of South Campus (Campus otty colloquially)
This is the area was a wetland during
the study period and now it is changed to a paddy field as part of Subhiksha Keralam Project. According to
authorities this area was paddy field around 30 years back. This was one of the
major support systems of the diversity of campus. The wetland had a depth of 2
meters maximum which was acting as the reservoir of water during summers. Also,
there was a transition phase of succession from the wetland to the dry area.
Nearly 30 meters from the wetland had a transition phase like character. This area had rich natural
flora which supported
all types fauna. Outside this
transition phase the entire area is covered by Acacia trees which were earlier
introduced as part of ‘Social Forestry Project’. Which is now being massively
cut are replaced by fruiting trees.
Site
2- Hymavathi Pond
This area is one of the most diverse
site of the entire campus. Hymavathi pond was also renovated and the natural
flora covering the pond was completely removed. Now the area is an open area
with the pond in the middle. Also the water quality in the pond poor. This may
have negative impact on the birds as well as other species. The areas near
Hymavathi pond is the extension of the earlier mentioned wetland of site 1
which is considered as part of this site as the area is observable from
Hymavathi pond.
Site
3- Main Campus
This is the area where most of the
departments are located. Anthropogenic activities are high in this area. Tree cover
is comparatively less when compared
to other sites. Waste accumulation can also be found in several
parts of this site which attract scavenging species like crows. Singapore
cherry plants are present in this area which attract birds.
Site 4-
North Campus
North campus is separated from main
campus by the road passing in between. North
campus can be considered as two parts. The areas near
botany department is used
as research fields. These areas
have very less tree cover. But the eastern part of the north
campus has thick natural vegetation. This area also has a wetland which act as the origin of the stream which flows down to
Kazhakkottam. The wetland area is deep and water is present in summer season
also. Acacia trees are comparably less in this
areas.
Materials
and Methods
Mainly three
methods were used for assessment of bird diversity. These are;
1)
Point count method
In this method points are selected in
a transect and the diversity is monitored in those selected points. In this
study the points were monitored twice in a week.
2)
Line transect method
In
this method a fixed route called transect
is monitored while moving
in a
constant pace. Line transect method reduce the chance of multiple
detection of individuals.
3)
Area count method
In this method a fixed area is
selected for monitoring. There is no fixed route for monitoring the fixed area.
Area count method is one of the mostly used study method for bird diversity.
Tools used for bird monitoring
The study area was monitored twice a
week for one year. The area was visited in the morning (7.00 to 10.00 am) and
in the evening (4.30 to 5.30pm). These are the times of a day where birds show
high level of activities.
Bird identification was done using
direct observations (Celstron 10x binocular was used) and identification after
photographing. Photographs were taken using Nikon Digital SLR camera (Nikon
d7200 with Nikkor200-500mm F/5.6E ED lens) and Sony HX 400v point and shoot
digital camera.
Bird
calls were played
and the reply calls were used for confirming the presence
of several species such as Indian Pitta and Black Baza.
Digital edition of the field guide
“Birds of Indian Subcontinent” by Grimmett and
Inskipp and websites
like Xeno-Canto (https://www.xeno-canto.org/) were used for clarifications.
Ebird.org website and the mobile
application were used to create checklists
and track the transects using GPS.
Results
93 species of birds belonging
to 16 Orders and 41 families were identified during the study period. Out of which Passeriformes represent
the largest order with 39 species
followed by Accipitriformes with 9 species; Pelecaniformes with 8 species;
Columbiformes and Coraciiformes with 5 species; Strigiformes and Cuculiformes with 4 species; Caprimulgiformes,
Suliformes and Piciformes with 3 species; Anseriformes,
Gruiformes, and Charadriiformes with 2 species
and Galliformes, Podicipediformes with 1 species.
Based of occurrence the birds are
classified into four categories which are rare, occasional, common and very
common. Out of the 91 species of birds 36% is very common, 31% is common,
27% is occasional and 6% is rare. Site 1 and 2 showed higher diversity compared to other two
sites.
Site wise
distribution
Site 1- South of South Campus
Site
1 showed highest
species richness then other sites. 79 species
of birds were reported form site 1. Passeriformes are the dominant species
in them.
Site 2- Hymavathi Pond
Hymavathi pond and nearby wetlands are
nearly as diverse as site 1 which had 78 bird sightings.
Site 3- Main Campus
This is the part of campus with most
human activities. This area reported a diversity of 33 species
of birds. This site has maximum population of Crows, Babblers, Rock pigeons etc.
Site 4- North Campus
47 species of birds were reported from
site 4. Site 4 has similarities in species distribution towards site 1.
Discussion
Urban diversity has a lot to do with
human life in urban areas. Kariavattom campus can be considered as one of the
biggest green islands in Thiruvanathaputram District. As it is located near one
of the most populated part of the city, this campus helps in keeping the
balance between nature and humans. Urban parks may serve as reservoirs for
native species in densely populated areas (Baker and Graf 1989, Goode 1991).
One of the main features of these natural settings within cities is
that they are heavily visited by people, who may potentially interact with
wildlife in different ways (Dickman 1987). human drivers of the patterns of biodiversity in urban areas, we must find ways to integrate social
science approaches with conventional ecological approaches to understanding
biological communities (Cadenasso et al. 2006). As humans actively
construct biological communities in cities, they may juxtapose
species that evolved on different continents and under different
biophysical conditions (Hobbs et al. 2006).
These novel communities often simultaneously have more total
species but fewer native
species than the surrounding native habitat (e.g., Marzluff 2001). These
drastic rearrangements of flora and
fauna are thought by some to be leading toward a global homogenization of
biotic communities and consequently a total reduction in global biological diversity (McKinney and Lockwood 1999) Thus natural
habitats have important role
in keeping native species.
Bird diversity can indicate the overall
diversity of a place as they come in the top
of food chain. First Avian
funa study was conducted by former student
HP. Nisanth as part of his PG dissertation. A total of 62 species
of birds belonging
to 14 orders were reported
from the study. (HP. Nisanth 2015). In the present study 93 species of birds
were identified, which belongs to 16 Orders and 41 families. Out of these birds
Passeriformes dominated in number. 39 species of Passeriformes were identified during the study which is much more when compared
to second largest
Accipitriformes with 9 species; and third largest
Pelecaniformes with 8 species.
The
diversity of passerines can be attributed to the availability of fruiting berries in the vegetation. As there is
rich vegetation in campus insects are also high in the campus. As most of the
passerines are Frugivorous or insectivorous, campus provides a proper
habitat for them. Also, species
vary in tolerance
levels; large species
seem less tolerant of humans than small ones (Cooke 1980),
as passerines are small birds this may
also contribute to the diversity. Accipitriformes were the second largest order
with 9 species which include ‘Black Baza’ which is a rare sighting in Kerala.
The diversity of Passeriformes can be attributed towards the diversity of Passeriformes.
As they are the birds of prey, they feed on small birds like passerines. As the
availability of small birds are high
the predators are also high. The third largest order was represented by
Pelecaniformes. These birds include egrets which are adapted to stalk and catch
fish in shallow waters. As site 1, site 2 and site 4 has similar habitats which
can support the Pelecaniformes.
In a site wise analysis site 1 ‘Campus
Ooty’ shows most diversity. As habitat structure increases in complexity, birds
show more tolerance to people since they have more available cover to hide from
visitors (Knight and Temple 1995). 79 species of birds were identified from site 1. It is very clear that the availability of undisturbed areas with a water source in the middle
had the pivotal role in holding the diversity. Site 2 ‘Hymavathi Pond and and
wetlands’ also had similar results. 78 species of birds were reported form this
site. One of the major reason behind this observation is that site 1 and 2
share some parts of the wetland earlier known as Pullekkonam Chira. This
wetland has a depth of nearly 2 meters towards the South side and gradually
depth reduces towards North.
Banks of this wetlands consists
of rich vegetations which remain green during
the entire period of a year. Also, there is water in the depths
of the wetland which acts as a reservoir
for summer season.
Site 1 and 2 play the major role in keeping
the diversity of this campus.
Site 3 ‘Main Campus’ is the most
disturbed areas of the campus. This is the areas of academic buildings. This
area reported the least diversity. Bird tolerance can be estimated by flush
distance, the distance at which a species escapes from a visitor; the larger
the flush distance, the less the tolerance (Cooke 1980). As these areas have
more humans birds with large
flee distances tend to stay away. As a complex
and better ecosystem is available the birds tend to remain in the site 1 and 2. Site 3 was dominated by Crows, Common Myna, Yellow
Billed Babbler and Rock Pigeons. Habituation to human presence may explain some
variation in tolerance levels; for instance, migrants are less tolerant than resident species
because of less contact with people throughout the year (Burger and Gochfeld 1991). These species tend to
scavenge on waste products and food leftovers. Also, flower peckers are well
distributed in site 3 as the number of Singapore Cherry Berry plants are high here.
Site 4 ‘North Campus’ is separated from
the Main Campus by the National Highway. Birds like Crows and babblers are
comparingly less which can be due to less
human activities and the separation from Main Campus.
But the Northern side of North
Campus is having similar habitat as of site 1 with even more natural
vegetation. This place also shows similarities with species distribution with
site 1.
Several rare observations were also
seen during the study. Black Baza reporting’s continue for past 5 years. An
albino variant of Jungle babbler is residing in the campus. Paradise flycatcher
with a mix of both white and rufous colour was also observed during the study
period. Spot-billed duck and little grebe was reported from site 1 which has
deep waters.
Out of 352 acres of land around
60% area are still covered
with vegetations. Out of which Acacia trees are dominated in
most areas. These areas are supporting such a rich diversity of birds, this
means there is resources which can support this unmatching diversity. The site 1, 2 and 4 are more diverse. These areas have natural vegetation
undergrowth which can support this much diversity.
Acacia trees were planted around 30
years back and the agriculture in wetlands were stopped around 30 years back.
The ecosystem has adapted over this time in order to thrive in this urban
ecosystem. And now it’s a strong ecosystem which support several species.
Recently, Acacia trees are massively removed and it is supposed to be replaced
with indigenous plants like Mangos and Jackfruit. The process of clearing is
rapid and the undergrowth is also wiped out. Also, the wetland which is shared
by site 1 and 2 in this study is also altered
and changed for agriculture by the end of this study.
Conclusion
This study was conducted after 5 years
after the previous study (Nisanth HP. 2015). Current study was able to report
marginally high number of species than that of the previous study. This can be due to the increase
in study periods.
The previous study was
conducted for a period of 3 months and the current study
was conducted for a period of
one year. But there is a clear increase in diversity. For proper conclusion more studies should
be conducted on the change avian diversity pattern and the effect of
biogeographical factors which contribute to this change.
Habitat is changed in a drastic manner
by the end of study period. The changes done as part of Acacia removal
and agriculture project
in the wetland will have huge impact on the pattern of diversity. The diving species
like ducks will have to move
from here. More waders are expected to come. A further study only can confirm
this pattern change.
Kerala University Campus Kariavattom
acts as a major support system of diversity in the city of Trivandrum. The
ecosystem provides several services like fresh water, suitable habitat for
flora and fauna and several other indirect benefits. Bird diversity can
indicate the diversity of other species as well. Birds are also having
importance in controlling insects, rodents etc. and keeping the food chain in
balance.
This
pristine habitat should
be conserved for the overall
wellbeing of the city of Trivandrum.
Proper environmental impact studies should be conducted before developmental
activities. This area cannot be considered as a normal campus, this is a place where the natural
fauna thrive along
with humans. We should protect
these areas.
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