Journal of Threatened Taxa | www.threatenedtaxa.org | 26 January 2024 | 16(1): 24557–24567

 

ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print) 

https://doi.org/10.11609/jott.8639.16.1.24557-24567

#8639 | Received 18 July 2023 | Final received 22 November 2023 | Finally accepted 15 December 2023

 

 

Assessment of diversity, abundance, and seasonal variations of bird species in Bengaluru District, India during COVID-19 lockdown

 

H. Hemanth 1, Rajalakshmi K.S. Vinanthi 2 & Kuppusamy Alagesan Paari 3

 

1,2,3 Department of Lifesciences, CHRIST (Deemed to be University), Dharmaram College Road, Hosur Road, Bengaluru, Karnataka 560029, India.

1 hemanth.h@res.christuniversity.in, 2 vinanthi.rajalakshmi@res.christuniversity.in, 3 paari.ka@christuniversity.in (corresponding author)

 

 

Editor: H. Byju, Coimbatore, Tamil Nadu, India.                    Date of publication: 26 January 2024 (online & print)

 

Citation: Hemanth, H., R.K.S. Vinanthi & K.A. Paari (2024). Assessment of diversity, abundance, and seasonal variations of bird species in Bengaluru District, India during COVID-19 lockdown. Journal of Threatened Taxa 16(1): 24557–24567. https://doi.org/10.11609/jott.8639.16.1.24557-24567

  

Copyright: © Hemanth et al. 2024. 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: None.

 

Competing interests: The authors declare no competing interests.

 

Author details: H. Hemanth and Rajalakshmi K.S. Vinanthi are currently pursuing their doctoral studies in zoology at the Department of Lifesciences, CHRIST (Deemed to be University), Bengaluru. Dr. Kuppusamy Alagesan Paari is working as an assistant professor at the Department of Lifesciences, CHRIST (Deemed to be University), Bengaluru.

 

Author contributions: HH carried out surveys, photography and identification of birds. RKSV make substantial contributions to acquisition of theoretical data, compilation of data and manuscript preparation. KAP have contributed towards the conception, designing of ideas and critical revision that has helped in the formation of the present research manuscript. All the authors reviewed and approved the final manuscript.

 

Acknowledgements: The authors wish to acknowledge the support received from the Centre for Research, CHRIST (Deemed to be University) (MRPDSC – 1936).

 

 

Abstract: The study investigates bird population dynamics in Bengaluru, India, post-lockdown, focusing on occurrence, seasonal abundance, species diversity, richness, dominance, and evenness. It covers 55 bird species across 52 genera, grouped into 32 families within 13 orders, with a notable peak in winter. Various indices, including Shannon Wiener, Margalef’s, Pielou’s, and Simpson’s, reveal significant seasonal differences in bird population characteristics. The Rock Pigeon Columba livia dominates, while the Black-headed Ibis Threskiornis melanocephalus is less prevalent. The study identifies Near Threatened species like Black-headed Ibis and Oriental Darter Anhinga melanogaster, along with Least Concern species per the IUCN Red List. Common species include Rock Pigeon, Large-billed Crow Corvus macrorhynchos, House Crow Corvus splendens, Black Drongo Dicrurus macrocercus, Brown Shrike Lanius cristatus, Common Myna Acridotheres tristis, Jungle Myna Acridotheres fuscus, Red-whiskered Bulbul Pycnonotus jocosus, and Streak-throated Swallow Petrochelidon fluvicola. The study aims to inform improved management and conservation strategies for Bengaluru’s diverse bird species.

 

Keywords: Avian abundance, bird diversity, conservation, lockdown effects, pollution indices, species evenness, species richness, threatened species, water bodies.

 

INTRODUCTION

 

Bengaluru, the fifth largest city in India, is known as the Garden City owing to its natural vegetation, rich parks, gardens, lakes, and streets lined with large canopied flowering trees (Rajashekara & Venkatesha 2016). Rapid urbanization and massive increase in population density have affected the existence and diversity of wildlife (Ramachandra et al. 2017; Yang et al. 2022). Birds are common inhabitants and are an important component of any ecosystem as they are involved in several trophic levels in the food web (Blair 1999). In the urban ecosystem, the development of huge green spaces contributed to the sustainable conservation of bird species (Campbell et al. 2022; Choudaj et al. 2023). The abundance of bird species and their variety within a specific region can have consequences for both terrestrial and aquatic ecosystems, which are interconnected within the broader food web (Turner 2003). The declining abundance of bird species in specific regions, particularly urban areas, is a cause for concern, especially when considering metrics related to urbanization and pollution (Donaldson et al. 2007).

Factors such as climatic stability and seasonality have a positive influence on avian diversity and are important determinants of avian diversity (Graham et al. 2006). In urban areas, compared to previous years, an increase in the daily mean number and visibility of a new proportion of bird species were witnessed during the COVID-19 pandemic seasons (Basile et al. 2021).  The avifaunal diversity reported in Bangladesh during lockdown revealed the relative abundance and detectability of Red-vented Bulbul Pycnonotus cafer which was directly related to their breeding season during the seasons from March to August (Shome et al. 2021). The diversity of biological resources depends on climatic, physical conditions, topographic features, altitudinal differences between highland and lowland areas, and the geological history of a region (Parmesan & Yohe 2003). Anthropogenic climate change has a widespread impact on many biological processes and migratory patterns of birds due to the unavailability of primary requirements of food, shelter, roosting, and nesting sites for birds which vary during different seasons (Cockrem 1995). A study by Shome et al. (2021) during the summer and rainy times of Covid pandemic seasons revealed the altered species composition of migratory birds belonging to the family Cuculidae. The restricted human activities and food limitations during the  COVID-19 pandemic had an impact on the progressive decline and in the abundance of Columbia livia in open feeding hotspots (Soh et al. 2021).

Biotic assemblages are significantly influenced by urbanization factors, leading to restricted turnover rates of bird species and reduced richness of native species due to human settlements (Godefroid 2001). The impact of COVID-19 on bird species, including richness, abundance, and diversity, has been substantial. Recent studies have highlighted the effects of lockdowns on avifauna populations, with observations of nearly 24 bird species’ abundance during the spring of 2020 in North America (Schrimpf et al. 2021). Uncommon species like the Black-rumped Flameback Dinopium benghalense, not reported in 2019 or the pre-period of 2020, became abundant during the lockdown in Bengaluru. Similarly, the Large-billed Crow was predominantly detected in the post-lockdown period of 2020 in New Delhi (Madhok & Gulati 2022). A study by Estela et al. (2021) on the nocturnal birds of Cali City, Colombia, revealed a decreased species richness of 40–58 % during lockdown restrictions.

The overnight limitations of anthropogenic activities (anthropause) led to the lag between the lockdown and species diversity which exhibited the gradual recovery of species. Though databases such as citizen sciences, iNaturalist, and eBird offer data on population statistics of bird species, scientific evidence concerning the pandemic impact on avifaunal diversity, and seasonal variation detectability is scarce. Therefore, the present article aims to focus on the occurrence, seasonal abundance, species diversity, species richness, species dominance, and species evenness of bird population in different seasons during the pandemic lockdown season. This generated data could be useful for designing high throughput conservation strategies for better management of the avian population.

 

 

MATERIALS AND METHODS

 

Study area and data collection

The research was conducted at Hinnakki Village Lake in the Bengaluru district of Karnataka, India (Figure 1), situated at 12.774N & 77.678E, with an altitude of 889 m (2,918 ft) in the southern part of Karnataka. The average annual rainfall in the region is approximately 1,958.6 mm, with maximum and minimum annual temperatures recorded at 36.7 °C and 13.9 °C, respectively. The dominant vegetation type in the selected study area is tropical deciduous. The study encompassed the lake region and adjacent habitats, including agroforestry, agricultural fields, and anthropogenic regions, as part of a systematic examination of the seasonal abundance of birds. Four seasons—winter (December–February), summer (March–May), monsoon (June–August), and retreating monsoon (September–November)—were considered for the study (Girma et al. 2017). The survey employed a point transect method (Newson et al. 2009), with four regions covering 12 spots spaced at least 300 m apart. The study period extended from December 2021 to November 2022, with surveys conducted in the morning (0630–0830 h) and early evening (1630–1830 h) during each site visit. Each spot was visited seasonally 20 times, and bird identification was conducted using CASON 8 x 40 binoculars. Bird frequency was categorized as rare (R), uncommon (UC), common (C), and very common (VC) following the protocol by Kumar & Gupta (1970). Photographs of birds were captured using a Sony DSCHX 400V 20MP camera, and bird identification and checklists were meticulously performed (Ali 2002; Manakadan et al. 2011; Grimmett et al. 2016).

 

Mathematical formulation for data analysis

Data analysis was carried out using the following equations:

Shannon Wiener index-The type of diversity used was α- diversity which is the diversity of species within a community or habitat. (Wiener diversity index 1949).

Diversity index: H = – ∑ Pi In Pi

where Pi = S ⁄ N

S = number of individuals of one species

N = total number of all individuals in the sample

ln = logarithm to base e

Margalef’s index was used as a simple measure of species richness (Margalef 1958).

Margalef’s index = ((S – 1))/ln N

S = total number of species

N = total number of individuals in the sample

ln = natural logarithm

Pielou’s Evenness Index (e) was used to calculate the evenness of species (Pielou 1966).

Pielou’s Evenness Index = e = H / In S

H = Shannon – Wiener diversity index

S = total number of species in the sample

Simpson’s diversity index (D) was used to calculate the species dominance (Simpson 1949).

Simpson index = D = 1 - (sum n * (n - 1) / N * (N - 1))

n = number of individuals of each species

N = total number of individuals of all species

Relative abundance

                       Number of checklists in which a bird is recorded

Relative abundance = –––––––––––––––––––––––––––– X 100

                                               Total number of checklists

 

 

RESULTS AND DISCUSSION

 

The ecology of birds is intricately tied to rainfall and vegetation, where fluctuations in these environmental factors have direct and indirect effects on avian abundance. Demographic parameters further contribute to the biodiversity shift in birds. In the study area, the total recorded rainfall was 1958.6 mm, with the highest monthly rainfall of 131.6 mm occurring in September. Summer temperatures ranged from a maximum of 36.7°C to a minimum of 24.2°C in April, while winter temperatures ranged from a maximum of 19.6°C to a minimum of 13.9°C in November. The highest diurnal temperature variation was 17°C in February (max = 33°C, min = 16°C), while the lowest was 1.8°C in December (max = 19.6°C, min = 17.8°C). The harsh environment significantly impacts vital rates in the avian population, with factors such as heat stress and hypothermia affecting survival and population trends. Rainfall, in particular, correlates with breeding success and factors associated with migratory bird assemblages. The study validates a positive correlation between environmental metrics and avian diversity and richness (Saracco et al. 2018).

A total of 55 species of birds belonging to 52 genera belonging to 32 families of 13 orders were recorded during the post-lockdown period in the study area (Imags 1–55; Figure 2). Among the observed bird species, 53 are classified as ‘Least Concern,’ while two species fall under the category of ‘Near Threatened,’ namely the Black-headed Ibis and the Oriental Darter (Table 1). The documentation included a total of 18 aquatic birds and 37 terrestrial birds. The Rock Pigeon was identified as the most commonly found species, constituting 6.935% of the observed bird population, owing to its behavioral adaptability to urban settings and resilience to anthropogenic disturbances (Polyavina et al. 2022). The Black-headed Ibis was found to be the most uncommon species (0.012%), which might be due to their preferred habitat and foraging areas such as shallow seasonal or permanent wetlands, marshlands, and water-logged crop fields (Barik et al. 2021). The decrease in marshy vegetation in the current study area due to the alteration of the landscape, which involves the construction of concrete buildings, and roads and also turning paddy fields into dry agricultural lands, affected the avian diversity. The order Passeriformes exhibited the highest relative abundance at 38.18%, attributed to Passerines’ predominant diet, which includes insects, nuts, seeds, nectar, berries, and fruits (Bhatti et al. 2017). Most of the passerines were found feeding on Indian Banyan Ficus bengalensis, Sacred Fig Ficus religiosa, Bur Flower-tree Neolamarckia cadamba, Jamaican Berry Muntingia calabura, and Bamboo Dendrocalamus sp. The family Ardeidae, encompassing herons and egrets, registered the highest relative abundance at 12.7%. The reason for their abundance might be due to the number of water bodies surrounded by a  huge number of trees and bushes, which facilitate the nesting of birds. The abundance and richness of Ardeidae species depend on the quality of water bodies, vegetation cover, and the availability of food (Ahlam et al. 2019).

The current observation held during the winter season showed the richness of bird species such as Grey-headed Swamphen Porphyrio poliocephalus, Black-winged Stilt Himantopus himantopus, Pied Kingfisher Ceryle rudis, White-cheeked Barbet Psilopogon viridis, and Rosy Starling Pastor roseus.  In the summer season, Indian Spot-billed Duck Anas poecilorhyncha, Indian Golden Oriole Oriolus kundoo, and Black-headed Ibis have been found (Figure 3). The significant variation in avifaunal diversity and abundance in different seasons could be due to seasonal migration patterns, habitat changes, and climatic conditions (Aynalem & Bekele 2008). Invasive exotic species such as Common Lantana Lantana camara, Alligator Weed Alternanthera phyloxiroides, Parthenium Weed Parthenium hysterophorus, Water Hyacinth Eichhornia crassipes, and Water Lettuce Pistia stratiotes was also observed. Biological invasion in water bodies can cause significant damage to the abundance of aquatic communities such as fish, zooplankton, and aquatic invertebrates (Schirmel et al. 2016). The biological oxygen demand of water bodies may, in turn, affect the bird population (Klemetsen et al. 2013; Mallin et al. 2016).

 

CONCLUSION

 

The present research provides information on the status of the bird population in the Bengaluru district. The conversion of green spaces into concrete structures due to urbanization has influenced bird diversity. Urbanization has varying control over the avian population. The study identified a reduction in the wetland bird population. A biodiversity shift was observed in the avian population of species such as Columba livia, Corvus macrorhynchos, and Corvus splendens, were seen in common wherein the density of the Near Threatened Threskiornis melanocephalus and Anhinga melanogaster populations was lower. Factors such as the magnitude of human activity during lockdown, pollution indices such as agricultural runoff, air and noise quality parameters, and food availability also influenced the migration pattern of birds. Regular monitoring of the wetland’s biodiversity is an important prerequisite to tracking the changes in avian population and diversity. The study also discussed the importance of confounding factors such as seasonal variations in the avian population. The involvement and support of residents are critical in conserving the vegetation, which can have a direct impact on the avian population and diversity.

 

 

Table 1. Encounter rates, occurrence, conservation status, and the diet type of avian communities reported in the study area.

Scientific name

Common name

Conservation status \ IUCN

Frequency of observation

Winter season

Summer season

Monsoon season

Retreating monsoon season

Total

Relative abundance

Anas poecilorhyncha

Indian Spot-billed Duck

LC

R

0

4

0

0

4

0.048

Threskiornis melanocephalus

Black-headed Ibis

NT

R

0

0

0

1

1

0.012

Egretta garzetta

Little Egret

LC

R

6

12

18

10

46

0.558

Ardea cinerea

Grey Heron

LC

R

5

8

2

2

17

0.206

Ardea purpurea

Purple Heron

LC

R

30

51

38

20

139

1.688

Mesophoyx intermedia

Intermediate Egret

LC

UC

50

77

85

60

272

3.303

Bubulcus ibis

Cattle Egret

LC

R

10

20

22

15

67

0.813

Ardeola grayii

Indian Pond Heron

LC

UC

40

59

75

55

229

2.781

Ardea alba

Great Egret

LC

R

5

10

15

9

39

0.473

Phalacrocorax fuscicollis

Indian Cormorant

LC

UC

80

60

70

50

260

3.158

Anhinga melanogaster

Oriental Darter

NT

R

3

2

0

0

5

0.061

Elanus caeruleus

Black-winged Kite

LC

R

1

2

0

0

3

0.036

Milvus migrans

Black Kite

LC

UC

58

62

51

55

226

2.745

Haliastur indus

Brahminy Kite

LC

UC

47

45

39

43

174

2.113

Accipiter badius

Shikra

LC

R

2

3

1

1

7

0.085

Amaurornis phoenicurus

White-breasted Waterhen

LC

UC

88

44

26

53

211

2.562

Porphyrio poliocephalus

Grey-headed Swamphen

NE

R

10

0

0

0

10

0.121

Fulica atra

Eurasian Coot

LC

R

5

10

20

15

50

0.607

Himantopus himantopus

Black-winged Stilt

LC

R

5

0

0

0

5

0.061

Vanellus indicus

Red-wattled Lapwing

LC

UC

65

50

60

66

241

2.927

Columba livia

Rock Pigeon

LC

VC

148

150

135

138

571

6.935

Spilopelia chinensis

Spotted Dove

LC

UC

50

62

45

40

197

2.393

Psittacula krameri

Rose-ringed Parakeet

LC

UC

50

60

84

78

272

3.303

Centropus sinensis

Greater Coucal

LC

UC

38

48

58

35

179

2.174

Eudynamys scolopacea

Asian Koel

LC

UC

59

45

40

33

177

2.149

Coracias benghalensis

Indian Roller

LC

R

20

5

8

15

48

0.583

Halcyon smyrnensis

White-throated Kingfisher

LC

UC

78

39

45

65

227

2.757

Ceryle rudis

Pied Kingfisher

LC

R

4

0

0

0

4

0.048

Merops philippinus

Blue-tailed Bee-eater

LC

R

35

39

31

34

139

1.688

Ocyceros birostris

Indian Grey Hornbill

LC

R

2

8

0

0

10

0.121

Upupa epops

Hoopoe

LC

R

4

3

0

0

7

0.085

Dinopium benghalense

Black-rumped Flameback

LC

R

2

0

0

0

2

0.024

Psilopogon viridis

White-cheeked Barbet

LC

R

5

0

0

0

5

0.061

Psilopogon haemacephalus

Coppersmith Barbet

LC

R

8

2

0

0

10

0.121

Lanius cristatus

Brown Shrike

LC

C

90

100

60

85

335

4.068

Oriolus kundoo

Indian Golden Oriole

LC

R

0

6

0

0

6

0.072

Dicrurus macrocercus

Black Drongo

LC

VC

180

210

75

50

515

6.255

Corvus splendens

House Crow

LC

C

110

113

60

70

353

4.287

Corvus macrorhynchos

Large-billed Crow

LC

VC

180

200

90

100

570

6.923

Pycnonotus jocosus

Red-whiskered Bulbul

LC

C

85

78

60

77

300

3.643

Pycnonotus cafer

Red-vented  Bulbul

LC

UC

70

50

30

50

200

2.429

Petrochelidon luvicola

Streak-throated Swallow

LC

C

100

135

50

80

365

4.433

Argya striata

Jungle Babbler

LC

R

6

3

2

3

14

0.171

Sturnia pagodarum

Brahminy Starling

LC

R

4

8

0

0

12

0.145

Acridotheres tristis

Common Myna

LC

VC

180

153

86

93

512

6.218

Acridotheres fuscus

Jungle Myna

LC

C

120

105

50

60

335

4.068

Pastor roseus

Rosy Starling

LC

R

150

0

0

0

150

1.821

Copsychus saularis

Oriental Magpie Robin

LC

R

30

21

22

20

93

1.129

Saxicoloides fulicatus

Indian Robin

LC

R

28

24

20

23

95

1.153

Terpsiphone paradisi

Indian Paradise Flycatcher

LC

R

1

2

0

0

3

0.036

Cinnyris asiaticus

Purple Sunbird

LC

R

20

12

5

8

45

0.546

Nectarinia zeylonica

Purple-rumped Sunbird

LC

R

15

10

5

5

35

0.426

Passer domesticus

House Sparrow

LC

UC

55

42

30

35

162

1.967

Motacilla maderaspatensis

White-browed Wagtail

LC

UC

79

74

63

67

283

3.437

Anthus rufulus

Paddy Field Pipit

LC

R

20

33

15

18

86

1.044

 

 

Table 2. Avian diversity in different seasons.

Biodiversity indices

Winter season

Summer season

Monsoon season

Retreating monsoon

Season

Shannon Wiener index (Species diversity)

3.434

3.379

3.408

3.4

Margalef’s index (Species richness)

6.506

6.052

5.112

5.228

Pielou evenness index (Species evenness)

0.869

0.873

0.93

0.922

Simpson’s index (Species dominance)

0.04

0.043

0.038

0.038

Number of encounters

2446

2359

1691

1737

Number of species

52

48

39

40

 

 

Table 3. Representation of the number of species belonging to each family observed in the study area.

Orders

Family

No. of genera

No. of species

Abun-dance

Anseriformes

Anatidae

1

1

1.81

Pelecaniformes

Threskiornithidae

1

1

1.81

 

Ardeidae

5

7

12.7

Suliformes

Phalacrocoracidae

1

1

1.81

 

Anhingidae

1

1

1.81

Accipitriformes

Accipitridae

4

4

7.27

Gruiformes

Rallidae

3

3

5.45

 

Recurvirostridae

1

1

1.81

Charadriiformes

Charadriidae

1

1

1.81

Columbiformes

Columbidae

2

2

3.63

Psittaciformes

Psittacidae

1

1

1.81

Cuculiformes

Cuculidae

2

2

3.63

Coraciiformes

Coraciidae

1

1

1.81

 

Alcedinidae

2

2

3.63

 

Meropidae

1

1

1.81

Bucerotiformes

Bucerotidae

1

1

1.81

 

Upupidae

1

1

1.81

Piciformes

Picidae

1

1

1.81

 

Megalaimidae

1

2

3.63

Passeriformes

Laniidae

1

1

1.81

 

Oriolidae

1

1

1.81

 

Dicruridae

1

1

1.81

 

Corvidae

1

2

3.63

 

Pycnonotidae

1

2

3.63

 

Hirundinidae

1

1

1.81

 

Sturnidae

3

4

7.27

 

Muscicapidae

3

3

5.45

 

Nectariniidae

2

2

3.63

 

Leiothrichidae

1

1

1.81

 

Passeridae

2

2

3.63

 

Motacillidae

1

1

1.81

13

32

49

55

 

 

 

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REFERENCES

 

Ahlam, C., B. Ettayib, M. Fateh & D. Soumia (2019). Effects of vegetation and water seasonal variation on habitat use of herons (Aves, Ardeidae) in Tonga Lake (North-East Algeria). Bolyai Biologia (2): 25–40. https://doi.org/10.24193/subbbiol.2019.2.03

Ali, S. (2002). The book of Indian birds. Oxford University  Press. New Delhi, 326 pp.

Aynalem, S. & A. Bekele (2008). Species composition, relative abundance and distribution of bird fauna of riverine and wetland habitats of Infranz and Yiganda at southern tip of Lake Tana, Ethiopia. Tropical Ecology 49(2): 199.

Barik, S., G.K. Saha & S. Mazumdar (2021). How the habitat features influence Black-headed Ibis (Threskiornis melanocephalus) in a suburban area? A study from mid-West Bengal, India. Proceedings of the Zoological Society of London 75(1): 39–47.

Basile, M., L.F. Russo, V.G. Russo, A. Senese & N. Bernardo (2021). Birds seen and not seen during the COVID-19 pandemic: The impact of lockdown measures on citizen science bird observations. Biological Conservation 256: 109079.

Bhatti, Z. (2017). A study on status and distribution of Passeriformes in Bagh district of Azad Kashmir. Journal of Bioresource Management 4(1): 3.

Blair, R.B. (1999). Birds and butterflies along an urban gradient: Surrogate taxa for assessing biodiversity? Ecological Applications 9(1): 164–170. https://doi.org/10.1890/1051-0761(1999)009[0164:babaau]2.0.co;2 

Campbell, C.E., D.N. Jones, M. Awasthy & A.L. Chauvenet (2022). How do we study birds in urban settings? A systematic review. Biodiversity and Conservation 31(1): 1–20.

Cockrem, J.F. (1995). Timing of seasonal breeding in birds, with particular reference to New Zealand birds. Reproduction, Fertility, and Development 7(1): 1–19.  https://doi.org/10.1071/rd9950001 

Choudaj, K. & C. Shaha (2023). Natural remnants are refuges for rare birds in an urban area: a study from Pune city, India. Ornis Hungarica 31(1): 62–71.

Donaldson, M.R., K.M. Henein & M.W. Runtz (2007). Assessing the effect of developed habitat on waterbird behaviour in an urban riparian system in Ottawa, Canada. Urban Ecosystems 10(2): 139–151. https://doi.org/10.1007/s11252-006-0015-2

Estela, F.A., C.E. Sanchez-Sarria, E. Arbelaez-Cortes, D. Ocampo, M. Garcia-Arroyo, A. Perlaza-Gamboa & I. MacGregor-Fors (2021). Changes in the nocturnal activity of birds during the COVID-19 pandemic lockdown in a neotropical city. Animal Biodiversity and Conservation 44(2): 213–217. https://doi.org/10.32800/abc.2021.44.0213

Gaston, K.J. & R.A. Fuller (2007). Biodiversity and extinction. Progress in Physical Geography 31(2): 213–225. https://doi.org/10.1177/0309133307076488

Godefroid, S. (2001). Temporal analysis of the Brussels flora as an indicator for changing environmental quality. Landscape and Urban Planning 52(4): 203–224. https://doi.org/10.1016/s0169-2046(00)00117-1

Girma, Z., Y. Mamo, G. Mengesha, A. Verma & T. Asfaw (2017). Seasonal abundance and habitat use of bird species in and around Wondo Genet Forest, south-central Ethiopia. Ecology and Evolution 7(10): 3397–3405.

Graham, C.H., C. Moritz  & S.E. Williams (2006). Habitat history improves prediction of biodiversity in rainforest fauna. Proceedings of the National Academy of Sciences of the United States of America 103(3): 632–636. https://doi.org/10.1073/pnas.0505754103

Grimmett, R., C. Inskipp & T. Inskipp (2016). Birds of the Indian Subcontinent: India, Pakistan, Sri Lanka, Nepal, Bhutan, Bangladesh and the Maldives. Bloomsbury Publishing, London, 528 pp.

Jetz, W., C.H. Sekercioglu & K. Böhning-Gaese (2008). The worldwide variation in avian clutch size across species and space. PLoS Biology 6(12): 2650–2657. https://doi.org/10.1371/journal.pbio.0060303

Julliard, R., F. Jiguet  & D. Couvet (2004). Common birds facing global changes: what makes a species at risk? Global Change Biology 10(1): 148–154. https://doi.org/10.1111/j.1365-2486.2003.00723.x 

Klemetsen, A. & R. Knudsen (2013). Diversity and abundance of water birds in a subarctic lake during three decades. Fauna Norvegica 33: 21–27. https://doi.org/10.5324/FN.V33I0.1584

Kumar, P. & S.K. Gupta (1970). Diversity and Abundance of Wetland Birds around Kurukshetra, India. Our Nature 7(1): 212–17.

Madhok, R. & S. Gulati (2022). Ruling the roost: Avian species reclaim urban habitat during India’s COVID-19 lockdown. Biological Conservation 271: 109597. https://doi.org/10.1016/j.biocon.2022.109597

Mallin, M., M. McIver, E. Wambach & A. Robuck (2016). Algal blooms, circulators, waterfowl, and eutrophic Greenfield Lake, North Carolina. Lake and Reservoir Management 32: 168–181. https://doi.org/10.1080/10402381.2016.1146374

Manakadan, R., J.C. Daniel & N. Bhopale (2011). Birds of the Indian Subcontinent: A Field Guide. Oxford University Press. India, 400 pp.

Mönkkönen, M., J.T. Forsman & F. Bokma (2006). Energy availability, abundance, energy-use and species richness in forest bird communities: a test of the species-energy theory. Global Ecology and Biogeography: A Journal of Macroecology 15(3): 290–302. https://doi.org/10.1111/j.1466-8238.2006.00224.x

Newson, S.E., N. Ockendon, A. Joys, D.G. Noble & S.R. Baillie (2009). Comparison of habitat-specific trends in the abundance of breeding birds in the UK. Bird Study 56(2): 233─243. https://doi.org/10.1080/00063650902792098

Parmesan, C. & G. Yohe (2003). A globally coherent fingerprint of climate change impacts across natural systems. Nature 421(6918): 37–42. https://doi.org/10.1038/nature01286

Pimm, S.L., C.N. Jenkins, R. Abell, T.M. Brooks, J.L. Gittleman, L.N. Joppa, P.H. Raven, C.M. Roberts & J.O. Sexton (2014). The biodiversity of species and their rates of extinction, distribution, and protection. Science 344(6187): 1246752. https://doi.org/10.1126/science.1246752

Polyavina, O.V. & M.A. Lebedeva (2022). The diversity of plumage coloration and behavioral features of synanthropic blue rock pigeon of urbanized territories. Samara Journal of Science 11(3): 106–111.

Rajashekara, S. & M.G. Venkatesha (2016). Seasonal Incidence and Diversity Pattern of Avian Communities in the Bangalore University Campus, India. Proceedings of the Zoological Society of London 70(2): 178–193. https://doi.org/10.1007/s12595-016-0175-x

Ramachandra, T.V., H.A. Bharath, G. Kulkarni & S. Vinay (2017). Green spaces in Bengaluru: quantification through geospatial techniques. Indian Forester 143(4): 307–320.

Root, T.L., J.T. Price, K.R. Hall, S.H. Schneider, C. Rosenzweig & J.A. Pounds (2003). Fingerprints of global warming on wild animals and plants. Nature 421(6918): 57–60. https://doi.org/10.1038/nature01333

Saracco, J., S. Fettig, G. Miguel, D. Mehlman, B. Thompson & S. Albert (2018). Avian demographic responses to drought and fire: a community-level perspective. Ecological Applications 28(7): 1773–1781.

Schirmel, J., M. Bundschuh, M.H. Entling, I. Kowarik & S. Buchholz (2016). Impacts of invasive plants on resident animals across ecosystems, taxa, and feeding types: a global assessment. Global Change Biology 22(2): 594–603.

Schrimpf, M.B., P.G. Des Brisay, A. Johnston, A.C. Smith, J. Sánchez-Jasso, B.G. Robinson & N. Koper (2021). Reduced human activity during COVID-19 alters avian land use across North America. Science Advances 7(39): eabf5073.

Shome, A.R., M.F. Jaman, M.F. Rabbe & M.M. Alam (2021). Bird diversity, composition and response during COVID-19 in an urban landscape, Jamalpur, Bangladesh. Dhaka University Journal of Biological Sciences 30(2): 261–274.

Soh, M.C., R.Y. Pang, B.X. Ng, B.P.H. Lee, A.H. Loo & B.H. Kenneth (2021). Restricted human activities shift the foraging strategies of feral pigeons (Columba livia) and three other commensal bird species. Biological Conservation 253(78): 108927.

Turner, W.R. (2003). Citywide biological monitoring as a tool for ecology and conservation in urban landscapes: the case of the Tucson Bird Count. Landscape and Urban Planning 65(3): 149–166. https://doi.org/10.1016/s0169-2046(03)00012-4

Walther, G.R., S. Berger & M.T. Sykes (2005). An ecologicalfootprintof climate change. Proceedings. Biological Sciences / The Royal Society 272(1571): 1427–1432. https://doi.org/10.1098/rspb.2005.3119

Yang, X., H. Cui & C. Chen (2022). Bird flight resistance analysis and planning strategies in urban regeneration areas: a case study of a certain area in Shenzhen, China. Sustainability 14(19): 12123. https://doi.org/10.3390/su141912123