Habitat Preferences of Birds in Singapore

1. Habitat Preferences of Birds
in Urban Singapore
.
A Geospatial Analysis of the distribution of Javan Mynahs, Rock Pigeons, and Oriental
Pied Hornbills across various Urban Habitats in Singapore
A0209679L
Yale-NUS College
YID3214 : Urban Ecological Systems
Prof. Stephen Pointing
18 April 2023

2. Abstract
This essay explores the habitat preferences of birds in Singapore, focusing on the
distribution of three bird species - the Javan mynah, the rock pigeon, and the Oriental
pied hornbill - across different urban habitats. Through a geospatial analysis of data
collected from inaturalist -the study found that the Javan mynah and feral pigeon are
well-adapted to various urban environments, including high density urban areas,
while the Oriental pied hornbill is more specialized and found only in certain forested
spaces. The findings are consistent with previous studies done around the world and
in Singapore, and they highlight the importance of conserving forested spaces for the
survival of certain bird species and integrating conservation goals into urban
planning to minimize ecological damage. However, the study's limitations, such as
using subjective observations and not differentiating between highly-manicured
parks and highly-forested nature reserves, suggest that the data collected may not
fully represent the bird species distribution across the entire city-state.

3. Contents
Abstract 2
1. Literature Review 4
1.1 Effect of Urbanization on Birds 4
1.2 Birds’ Adaptation to Urban Areas 4
1.3 Habitat Preferences of Birds 5
1.4 Urban Habitat Preferences of Birds 5
1.5 Singapore Context 6
2. Study Design 7
2.1 Selected Bird Species 7
2.2 Categorization of Urban Habitats for Analysis 8
2.3 Research Questions 8
2.4 Assumptions 8
3. Methods 9
3.1 Data Collection (Observations) 9
3.2 Data Collection (Maps) 9
3.3 Data Manipulation 9
3.4 Data Processing 10
4. Findings 11
4.1 Javan Mynah Distribution 12
4.2 Feral Pigeon Distribution 14
4.3 Oriental Pied Hornbill Distribution 16
5. Discussion 18
6. Limitations 18
References 19

4. 1. Literature Review
Urbanization is a global phenomenon that has resulted in the loss of natural habitats
and biodiversity, including birds. Singapore, a rapidly urbanizing city-state, is not
immune to these changes, and its avian biodiversity is facing ecological damage. The
integration of conservation goals into urban planning is essential to minimize this
damage, and studies on bird-habitat relationships in Singapore are crucial to protect
avian biodiversity.
1.1 Effect of Urbanization on Birds
Urbanization has a significant negative impact on bird diversity (Chace & Walsh,
2006; McKinney, 2008). The loss and degradation of natural habitats due to
urbanization have reduced the amount of suitable habitat for many bird species in
Singapore (Blair, 1996). The fragmentation of remaining natural habitats also results
in a decline in species richness and abundance (Fahrig, 2003). Furthermore, the
increased presence of non-native species in urban areas, often introduced
intentionally or unintentionally, has resulted in competition for resources and prey
on native birds (Clergeau et al., 2001). Changes in the physical environment due to
urbanization, including increased noise levels and light pollution, have disrupted
communication between birds and altered their behavior and physiology (Francis &
Barber, 2013; Dominoni et al., 2016).
1.2 Birds’ Adaptation to Urban Areas
However, some bird species have adapted to urbanization and thrive in urban areas.
Generalist species such as house sparrows (Passer domesticus) and rock pigeons
(Columba livia) that can tolerate a wide range of habitats are often the most
successful urban birds (Blair, 1996; McKinney, 2008). But the dominance of these
species can result in a homogenization of bird communities in urban areas and
reduced biodiversity (McKinney, 2006). Therefore, conservation strategies that
consider the protection of specific bird species, habitats, and the preservation of
biodiversity in urban areas are crucial.

5. 1.3 Habitat Preferences of Birds
Birds prefer habitats that provide suitable vegetation characteristics, including
vertical structure, floristic composition, and landscape context (McElhinny et al.,
2006). The complex vegetation structure increases the availability of foraging and
breeding resources, which increases the number and diversity of bird species that an
area can support (Tassicker et al., 2006). Moreover, the type of habitat preferred varies
among bird species, such as river corridors, woodlands, and structurally complex
habitats (Gordon et al., 2009).
1.4 Urban Habitat Preferences of Birds
Birds have been found to adapt and thrive in urban environments, although
urbanization can impact the diversity and structure of bird communities. Studies
show that different urban habitats affect bird communities differently, and that
there is no single factor that determines their preferences. For instance, in a study
conducted in northern Finland, the similarity between urban bird communities was
dependent on the size of the town, the location of the study site within the town, and
especially the local habitat structure. While different habitat factors affected bird
species abundances, single-family house areas were found to be important
biodiversity hotspots in cities in wintertime, and it is important to understand the
factors affecting the occurrence of birds in these areas in order to maintain or
increase diversity on winter birds in other urban habitats (Jokimäki et al., 2003).
Another study found that the diversity of native bird species in a large forested park
was comparable to that of a forest tract outside the urban influence, while small or
highly modified parks contained fewer species, a greater proportion of species typical
of urban areas, few regularly occurring species, and most native forest species in
reduced abundance and frequency (Gavareski, 1976). Landscape forest cover and park
area by distance metrics have been shown to affect bird diversity and abundance
within urban areas, although the evidence supporting the hypothesis that
broad-scale habitat measures are better predictors of bird species and nesting guild
presence than local-level habitat measures was not conclusive. In the North
American context, local variables such as freshwater (streams), large conifers, and
large berry-producing shrubs such as salmonberry, blackberry, and elderberry, have
consistently shown significant relationships with the presence of a variety of bird
species - suggesting that availability of sources of food and sustenance strongly
correspond to the availability and variety of birds.

6. 1.5 Singapore Context
Lim and Sodhi (2004) studied the abundance of common bird species in Singapore
and found that most of these species are omnivorous or granivorous and are either
tree or shrub nesters, reflecting the opportunistic exploitation of urban resources.
The authors also found that there were no consistent patterns associated with
particular feeding or nesting guilds that could have conferred an advantage in
Singapore's rapidly changing urban environment. A recent study by Maklakov et al.
(2011) found that relative brain size is larger for passerine birds that are successful in
urban areas, suggesting that behavioral traits such as adaptability can be important.
The authors caution against interpreting the increase in abundance of urban bird
species as strong evidence for a healthy urban ecological system. Many of these
species are not native residents and the increasing dominance of these species may
imply that out-competition of the rarer native species is already occurring.
The annual bird censuses in Singapore provide long-term nationwide data from
which population trends and fluctuations have been inferred (Chong er al., 2012). The
census data is a volunteer effort and has its own limitations, such as considerable
variation in sampling effort and observer experience between places and years.
In conclusion, Lim and Sodhi's (2004) study suggests that the most common bird
species in Singapore are opportunistic exploiters of urban resources, and their
success is likely attributed to their adaptability. However, caution should be
exercised when interpreting the increase in abundance of these species as a sign of a
healthy urban ecological system. Long-term and comparable data is required to
explore the dynamism in community structure, and the impact of competition on the
native bird species should be further investigated.

7. 2. Study Design
The aim of this study is to analyze the distribution of three bird species in different
urban habitats in Singapore. The selected bird species are the Javan mynah, the rock
pigeon, and the Oriental pied hornbill. The study focuses on the distribution of these
species across four different types of urban habitats: Parks & Green, Low rise/density
residential, High rise/high density residential, and High Rise Commercial.
2.1 Selected Bird Species
The three bird species selected for this study are the Javan mynah, the rock pigeon,
and the Oriental pied hornbill. The Javan Mynah and the Feral Pigeon are generally
well-suited to the urban environment, while the Oriental Pied-Hornbill is not. By
selecting these species, we aim to explore how bird species with varying levels of
adaptability to the urban environment are distributed across different urban habitats
in Singapore.
The Javan Myna is an introduced bird species found in many Asian countries,
including Singapore, where it is a common resident. Its breeding range is in Java,
Indonesia. The Javan Myna is typically found in open habitats, such as scrub
vegetation and forest edges. They are omnivorous birds and can forage on the ground
and sometimes in trees. They are often associated with human settlements and can
be found in urban habitats. (Y.C. Wee et al., 2008)
The Feral Pigeon, also known as the rock pigeon or common pigeon, is a polytypic
bird species that is found worldwide in urban and open areas. They are descendants
of wild rock pigeons and have partially conserved the foraging behavior of their
ancestors, but have also adapted to the urban environment. The feral pigeon's
individual foraging strategies and adaptability to different urban environments make
them a common introduced resident with a least concern conservation status. (Rose
et al., 2006, p. 242)
The Oriental Pied Hornbill is a medium-sized bird found in wooded areas, forest
edges, gardens, and parks throughout Southeast Asia, including the islands of
Sumatra, Borneo, and Java. It is an adaptable species and is able to thrive around
human habitation as long as there is an ample supply of food and large mature trees
for nesting. In Singapore, Oriental Pied Hornbills are commonly found in urban areas
bordering green spaces, such as Pasir Ris Park, Bishan Ang Mo Kio Park, and Pulau
Ubin, and are likely to occur in most parkland, especially where fruiting trees are
present. (Wee et al., 2008, p. 72)

8. 2.2 Categorization of Urban Habitats for Analysis
Based on the literature review, I chose four types of urban habitats for analysis. These
habitats represent different kinds of urban environments that are likely to attract
different bird species (Melles et al., 2003; Stagoll et al., 2010; Jokimaki et al., 2003).
The four habitats are as follows:
● Parks & Green: These habitats provide important urban habitats for a variety
of bird species, with trees, water bodies, and food sources.
● Low rise/density residential: This habitat attracts bird species that prefer
suburban areas, with trees, small parks, and gardens for food and nesting.
Studies have suggested that birds might prefer this habitat as an ideal urban
environment.
● High rise/high density residential: This habitat has a limited range of bird
species, with pigeons and mynahs being common, and a lack of nesting sites.
● High Rise Commercial: This habitat has very limited habitats for bird species,
with some opportunistic nesting on building ledges and rooftops due to its
glass architecture. It also has fewer food sources compared to other areas.
2.3 Research Questions
The study aims to answer two main research questions:
● Where are the selected bird species, with varying levels of adaptability to the
urban environment, distributed across the city?
● How are the selected bird species distributed across the different urban
habitats - as categorized by this study?
2.4 Assumptions
Based on the literature review and our understanding of the local context, I had the
following preliminary assumptions:
● Green spaces and parks are likely to have the highest concentration of birds,
even species that are well-adapted to urban environments. (Gavareski, 1976)
● Low-density residential areas are likely to be attractive to birds due to the
presence of trees and the low density of human activity. (Jokimaki et al., 2003)
High-density residential areas would still attract birds as they can be a source
of food. (Rose et al., 2006)
● High-density commercial areas would be the least attractive to birds due to
their tall skyscrapers that do not provide ideal habitats for birds and for
having fewer food sources than residential areas. (Stagollet al., 2010)

9. 3. Methods
The methodology used for this study involved a comprehensive approach that
included geospatial data collection, manipulation, and processing.
3.1 Data Collection (Observations)
To gather data on the three bird species of interest, I began by accessing iNaturalist,
a citizen science platform that enables users to record and share observations of
organisms. Specifically, for each species (Rock Pigeon, Javan Mynah, Oriental Pied
Hornbill), I set the map extent to Singapore and selected the attributes of interest,
including - id, common name, scientific name, latitude, and longitude. Using these
criteria, I downloaded all of the 'research grade' or verifiable observations available for
each species in Singapore. The total number of observations generated for each
species were as follows -
Bird Species Javan Mynah Feral/Rock Pigeon Oriental Pied Hornbill
Observations 2286 1105 1329
3.2 Data Collection (Maps)
To create the necessary maps for my analysis, I collected different layers from various
sources, as no single source had all the required layers. The basemap, The ‘National
Map Polygon - 2019’, was obtained from the Singapore Land Authority site (2019). I
collected data and shapefiles on parks and nature reserves from the National Parks
Board (2022). Building height limits were obtained from the Urban Redevelopment
Authority (2017). The 'Master Plan 2014 Building' was used to provide data on
high-density residential and low-density landed areas. (Urban Redevelopment
Authority, 2014)
3.3 Data Manipulation
After importing all the maps into the QGIS software, I layered the different zones and
map layers to create a comprehensive representation of the spatial data. I then
manipulated the existing shape files to reflect the specific categorizations I had
created for the study.
● To form the "Parks & Green" layer, all parks, nature reserves, and green spaces
in Singapore were merged into a single file.
● To form the “High-Density Residential” layer, I added a 50 m buffer around all
public and private residential buildings (above 10 floors) and merged them.

10. ● To create the “Low-Density Residential” layer - the same buffer was applied to
the low-density residential zones, heritage zones, and landed housing areas.
● Finally, buildings that were zoned as 10 floors or above and located within
commercial zones were merged under a single layer called 'high-density
commercial.'
To process the observation data, which was in point data format, I also imported it
into the same QGIS file for further analysis. The latitude and longitude attributes of
the iNaturalist data were used to place the observations at exact locations on the
map.
3.4 Data Processing
I used the spatial analysis tool to intersect the observation data for each bird species
with the various urban habitat zones. The result of the intersection - i.e the number of
points (observations) for each species within a zone - was counted using the
attribute table. This was then converted into a percentage of total observations for
that species within that zone.
To illustrate, suppose that I observed rock pigeons ten times in total. If five of these
observations occurred within green spaces, then I labeled green spaces as having
50% of the rock pigeon observations. In other words, 50% of rock pigeon observations
were found within green spaces.

11. 4. Findings
In this section, the findings are presented using geospatial maps and data generated
by Qgis. The objective is to identify patterns in the data and examine atypical clusters
and distribution of birds in different urban habitats throughout the city. The study is
conducted on a case-by-case basis with separate sections for each bird species,
namely the Javan mynah, rock pigeon, and Oriental pied hornbill. Finally, a
comparative analysis of the distribution and adaptation of these bird species across
different urban habitats is presented.

12. 4.1 Javan Mynah Distribution
Based on the observation data provided, the distribution of Javan mynahs in
Singapore appears to be relatively even across different urban habitats. The highest
percentage of observations were in high-rise residential areas (32%), followed by
parks and nature reserves (27%). Interestingly, there were also significant numbers of
observations in the "others" (i.e. industrial areas, air bases) category (28%), indicating
the presence of Javan mynahs in various urban settings.
Urban
Habitat
Parks, Nature
Reserves
Low Rise/
Density Areas
High Density
Residential
High Density
Commercial
Others
n 617 137 732 161 639
% n 27% 6% 32% 7% 28%
Figure Distribution of the Javan Mynah across various urban habitat types

13. While the distribution seems relatively even, the observations show some spatial
clustering of the Javan mynahs in certain areas. For example, in parks and nature
reserves, there were clusters of observations around the Botanic Gardens and
Gardens by the Bay. Similarly, in high-rise residential areas, there were clusters of
observations around Hougang 405A and University Town in NUS.
Figure Javan Mynah observations around Hougang Block 405
Figure Javan Mynah observations around civic district and Little India
It is worth noting that there were very few observations in low-rise/density areas (6%)
and high-rise/commercial areas (7%). However, the observations in high-rise
commercial areas were mostly around the open spaces between the commercial
skyscrapers in the civic district.

14. 4.2 Feral Pigeon Distribution
Based on the observations, the feral pigeon distribution in Singapore varies
significantly across different urban habitats. The highest concentration of feral
pigeons was found in parks and nature reserves, with 24% of observations recorded
in these areas.
Urban
Habitat
Parks, Nature
Reserves
Low Rise/
Density Areas
High Density
Residential
High Density
Commercial
Others
n 265 44 409 166 221
% n 24% 4% 37% 15% 20%
Figure Distribution of the Rock/Feral Pigeon across various urban habitat types

15. However, it was noted that feral pigeons were mostly concentrated around the
Botanical Gardens within these green spaces and parks. The low-rise/density areas
recorded the lowest number of observations, accounting for only 4% of total
observations. This could be due to the lack of abundant food sources in these areas
or the preference of feral pigeons to be around tall structures like trees and buildings,
as their natural habitat was cliffs.
Figure Feral Pigeon observations around Hougang Block 405
The feral pigeon population was found to be highly concentrated around high-rise
residential areas, with 37% of total observations recorded in these areas. This could
be due to the abundance of food and the adaptability of feral pigeons to high places.
Block 405 was observed to have a high-density cluster of pigeon observations,
although the reason for this remains unclear.
Figure Feral Pigeon observations around Little India
Surprisingly, feral pigeons were also found to be abundant in high-rise commercial
areas, accounting for 15% of total observations. Little India was observed to have a
high concentration of feral pigeons, especially around hawker centers and shopping
malls. This could be due to the open grocery stores and restaurants that attract these
birds.

16. 4.3 Oriental Pied Hornbill Distribution
The distribution of the oriental pied hornbill across different urban habitats in
Singapore shows that they are mostly found in parks and nature reserves (68% of
observations).
Urban
Habitat
Parks, Nature
Reserves
Low Rise/
Density Areas
High Density
Residential
High Density
Commercial
Others
n 905 80 212 40 92
% n 68% 6% 16% 3% 7%
Figure Distribution of the Oriental Pied Hornbill across various urban habitat types

17. Figure Hornbill observations around Pasir Ris Park (bottom) and Pulau Ubin (top)
However, it is worth noting that most of these observations are in specific green
spaces that are more forested or have a rainforest-like habitat compared to typical
Singaporean parks. These observations are found in places such as Singapore
Botanic Gardens, Jurong Bird Park, Pasir Ris Park, Pulau Bin, and Coney Island. The
hornbills are not found in high-density areas, this may be because these areas do not
have tall trees with cavities that hornbills can use for nesting.
Figure Hornbill observations around Yale-NUS College (cluster at the top)
The recorded observations in high-density residential areas cluster around Yale-NUS
College, which could be considered an outlier. (which could be attributed to
researchers or students interested in or studying hornbills). On the other hand,
hornbills were not observed in high-density commercial areas.

18. 5. Discussion
The nature of distribution of the three bird species, Javan mynah, feral pigeon, and
oriental pied hornbill, have been found to be consistent with literature elsewhere in
the world, and with previous studies in Singapore.
The Javan mynah seems to have adapted well to the urban environment, as
evidenced by their even distribution across various urban habitats. They are
omnivorous and forage on the ground and in trees, and are often associated with
humans in urban habitats. This is consistent with previous studies that have argued
that the heterogeneous landscape of Singapore, consisting of disjointed patches, has
led to a clustered distribution of the mynahs across the city-state. (Justin et al., 2013)
The feral pigeon also seems to have adapted well to the urban environment, with a
higher abundance in high-rise residential and commercial areas. They are also often
associated with humans, as evidenced by their abundance around hawker centers
and shopping malls. This is also consistent with previous studies that have also
found that feral pigeons have individual foraging strategies and are flexible enough
to adapt to different urban environments. (Rose et al., 2006)
In contrast, the oriental pied hornbill is found only in certain forested spaces. This
makes sense, as the hornbill's habitat includes open habitat, scrub vegetation, and
forest edges, and they are often found in large trees. Moreover, hornbills are
secondary cavity nesters and require cavities high up in tall living trees. Past studies
have shown that these cavities are not common in Singapore, especially in urban
areas, where old trees are considered a hazard to public safety. (Wee et al., 2008)
Overall, the findings suggest that the adaptation of these bird species to urban
environments varies, with the Javan mynah and feral pigeon being well adapted and
found across Singapore, and the oriental pied hornbill being more specialized and
found only in certain forested spaces. The findings also highlight the importance of
conserving forested spaces for the survival of certain bird species.
6. Limitations
The study's limitations stem from using observations collected from inaturalist,
which is influenced by factors like location and observer behavior. This could result
in skewed data, such as higher observations of certain bird species in certain areas
(Yale-NUS College, Hougang 405A) or popular areas for bird watchers (Coney Island,
Pasir Ris Park, and Pulau Ubin). Additionally, the study did not differentiate between
highly-manicured parks and highly-forested nature reserves, which have different
flora and fauna compositions. (Gavareski, 1976) Therefore, the data collected may not
fully represent the actual bird species distribution across the entire city-state.

19. References
● Richard K. Lancaster and William E. Rees. 2011. Bird communities and the
structure of urban habitats. Canadian Journal of Zoology. 57(12): 2358-2368.
https://doi.org/10.1139/z79-307
● Stagoll, K., Manning, A.D., Knight, E., Fischer, J. and Lindenmayer, D.B., 2010.
Using bird–habitat relationships to inform urban planning. Landscape and
urban planning, 98(1), pp.13-25.
● Gavareski, C.A., 1976. Relation of park size and vegetation to urban bird
populations in Seattle, Washington. The Condor, 78(3), pp.375-382.
● Melles, S., Glenn, S. and Martin, K., 2003. Urban bird diversity and landscape
complexity: species–environment associations along a multiscale habitat
gradient. Conservation Ecology, 7(1).
● Seress, G. and Liker, A., 2015. Habitat urbanization and its effects on birds. Acta
Zoologica Academiae Scientiarum Hungaricae, 61(4), pp.373-408.
● Jokimäki, J. and Kaisanlahti‐Jokimäki, M.L., 2003. Spatial similarity of urban
bird communities: a multiscale approach. Journal of Biogeography, 30(8),
pp.1183-1193.
● Chong, K.Y., Teo, S., Kurukulasuriya, B., Chung, Y.F., Rajathurai, S., Lim, H.C. and
Tan, H.T., 2012. Decadal changes in urban bird abundance in Singapore. The
Raffles Bulletin of Zoology, 25(1), pp.189-196.
● Chace, J.F. and Walsh, J.J., 2006. Urban effects on native avifauna: a review.
Landscape and urban planning, 74(1), pp.46-69.
● McKinney, M.L., 2008. Effects of urbanization on species richness: a review of
plants and animals. Urban ecosystems, 11, pp.161-176.
● Blair, R.B., 1996. Land use and avian species diversity along an urban gradient.
Ecological applications, 6(2), pp.506-519.
● Fahrig, L., 2003. Effects of habitat fragmentation on biodiversity. Annual review
of ecology, evolution, and systematics, 34(1), pp.487-515.
● Clergeau, P., Jokimäki, J. and Savard, J.P.L., 2001. Are urban bird communities
influenced by the bird diversity of adjacent landscapes?. Journal of applied
ecology, 38(5), pp.1122-1134.
● Francis, C.D. and Barber, J.R., 2013. A framework for understanding noise
impacts on wildlife: an urgent conservation priority. Frontiers in Ecology and
the Environment, 11(6), pp.305-313.
● Dominoni, D.M., Borniger, J.C. and Nelson, R.J., 2016. Light at night, clocks and
health: from humans to wild organisms. Biology letters, 12(2), p.20160015.
● McKinney, M.L., 2006. Urbanization as a major cause of biotic homogenization.
Biological conservation, 127(3), pp.247-260.

20. ● McElhinny, C., Gibbons, P., Brack, C. and Bauhus, J., 2006. Fauna-habitat
relationships: a basis for identifying key stand structural attributes in
temperate Australian eucalypt forests and woodlands. Pacific Conservation
Biology, 12(2), pp.89-110.
● Tassicker, A.L., Kutt, A.S., Vanderduys, E. and Mangru, S., 2006. The effects of
vegetation structure on the birds in a tropical savanna woodland in
north-eastern Australia. The Rangeland Journal, 28(2), pp.139-152.
● Bennett, E.M., Peterson, G.D. and Gordon, L.J., 2009. Understanding relationships
among multiple ecosystem services. Ecology letters, 12(12), pp.1394-1404.
● Lim, H.C. and Sodhi, N.S., 2004. Responses of avian guilds to urbanization in a
tropical city. Landscape and urban planning, 66(4), pp.199-215.
● Maklakov, A.A., Immler, S., Gonzalez-Voyer, A., Rönn, J. and Kolm, N., 2011. Brains
and the city: big-brained passerine birds succeed in urban environments.
Biology letters, 7(5), pp.730-732.
● Y.C. Wee, K.C. Tsang, Melinda Chan, Y.M. Chan, & Angie Ng. (2008). Birding in
Singapore's Southern Islands. BirdingASIA, 9, 72-77.
● Rose, E., Nagel, P., & Haag-Wackernagel, D. (2006). Spatio-temporal use of the
urban habitat by feral pigeons (Columba livia). Behavioral Ecology and
Sociobiology, 60, 242-254.
● Hernowo, J.B. (2017). Population analysis of Bali Mynah (Leucopsar rothschildi
Stresemann 1912) released in 2007 in Bali Barat National Park, Indonesia.
International Journal of Tropical Drylands, 1(2), 83-89.
● Justin, B.T.C., Eng, O.K., Rui, O.X. and Eunice, S.J.Y., 2013. Spatial Distribution of
Javan mynas in Singapore.
● Wee, Y.C., Tsang, K.C., Chan, M.E.L.I.N.D.A., Chan, Y.M. and Ng, A., 2008. Oriental
pied hornbill: Two recent failed nesting attempts on mainland Singapore.
Birding Asia, 9, pp.72-77.
● Cremades, M., Chye, N.S., Min, L.H. and Martelli, B., 2016. Re-introduction of the
oriental pied hornbill in its historical range in Singapore. Global
Re-introduction Perspectives: 2016. Case-studies from around the globe, p.102.
● Singapore Land Authority. (2019). National Map Polygon [Data set]. Singapore
Open Data Licence. Retrieved October 8, 2019, from
https://data.gov.sg/dataset/national-map-polygon
● National Parks Board. (2022). NParks Parks and Nature Reserves [Data set].
Singapore Open Data Licence. Retrieved October 31, 2022, from
https://data.gov.sg/dataset/nparks-parks-and-nature-reserves
● Urban Redevelopment Authority. (2017). SDCP Building Height Control
Plan-Storey [Data set]. Singapore Open Data Licence. Retrieved June 14, 2017,
from https://data.gov.sg/dataset/sdcp-building-height-control-plan-storey

21. ● Urban Redevelopment Authority. (2017). SDCP Landed Housing Area [Data set].
Singapore Open Data Licence. Retrieved June 14, 2017, from
https://data.gov.sg/dataset/sdcp-landed-housing-area
● Urban Redevelopment Authority. (2014). Master Plan 2014 Building (SHP) [Data
set]. Retrieved from
https://geo.data.gov.sg/g-mp14-bldg-pl/2014/06/23/shp/g-mp14-bldg-pl.zip