After a Decade: A Study of the Terrestrial Birds Species in Keoladeo National Park

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R. Venkitachalam

Dr. R. Venkitachalam is a Research Associate at Ashoka Trust for Research in Ecology and the Environment (ATREE), Bangalore. He has completed research projects on Hornbills in the Eastern Ghats, one on Ecosystem monitoring (Component Ornithology) in Keoladeo National Park, involved captive management programme on vultures conservation in India and two projects on in situ Conservation of vultures in Tamil Nadu. At present he is studying dynamics of ecosystem services in Western Ghats of Tamil Nadu.

Introduction

After a gap of almost a decade, a terrestrial birds study was carried out at the Keoladeo National Park for four selected habitats. A total of 109 species from 31 families of terrestrial birds were recorded during the study period (2005-2006), a much lower figure compared to the 157 species recorded by Sundaramoorthy in 1991. Additionally, Sundaramoorthy recorded 24 bird species with a dominance index value higher than one. In the present study only 10 bird species had an index value higher than one from 2004 to 2006. The park was known to be a staging ground for many migratory species. After a decade considerable changes have been observed in the Park such as habitat alteration mass mortality of vultures and a reduction in the number of migratory bird species coming to the park. Immediate long-term ecological studies are needed to understand the driving factors responsible for the present situation in this well-known Ramsar Site of India. 

 

Birds are one of the best indicators of the health of an eco-system. Avian community studies are effective tools for monitoring a forest ecosystem (Jayson 2000). Birds are highly mobile vertebrates and easily observed indicators of change (Graber and Graber 1976; Morrison 1986). Understanding patterns in species richness and species abundance is one of the fundamental goals in ecology (May 1973; Berlow 1999; McCann 2000; Hubbel 2001). The diversity and community structure of birds were also studied by Johnsingh et al (1987), Katti (1989), Daniels (1989), Daniels (1996) and Gokula and Vijayan (1996). The diversity of tropical forest birds has been studied in South America and in many other countries. Similar studies in other regions examined the structure of forest bird communities (Terborgh et al 1990), distribution (Howe et al 1981) and community organization (Landers and Mac Mahon 1980). The present study was carried out from 2004 to 2006 which was almost a decade after the study by Sundaramoorthy (1991).  Hence four terrestrial habitats were selected to study bird species diversity and richness in KNP.

 

Study Area

The Keoladeo National Park (KNP) Bharatpur  is located between 27°7.6’ to 27°12.2’ N and 77°29.5’ to 77°33.9E and lies 50 km west of Agra and 180 km south of New Delhi. The average elevation of the area is about 174 m above sea level (Fig.1)

 

Fig.1.Keoladeo National Park

 

The Keoladeo National Park came into existence about 131 years ago as Keoladeo Ghana during the reign of Maharaja Jaswant Singh of Bharatpur State when he fenced the jheel (lake) and the surrounding forest area (Ali and Vijayan 1983). The main purpose was to prevent the feral cattle which existed in the area from damaging the crops of the surrounding villages (Brijendra Singh 1981). The submersible area has been divided into various unequal blocks by means of dykes. The blocks are numbered alphabetically for identification in the work programme.  

 

The Park draws water every year during monsoon from Ajan Bund, an inundation reservoir fed by the water of the rivers Gambhir and Banganga on whose floodplain, Bharatpur is situated. It is connected by the canal which passes through the park and enters Jattoli village on the east. On either side of this canal lies the wetland extending to an area of about 8.5 sq.km, divided into several blocks by earthern bunds. Flow of water into these blocks is regulated by sluice gates. After letting in water to the desired level in each block the sluice gates from the main canal are closed. The water depth in the wetland varies from 0 to 200cm. None of the terminologies of Champion and Seth (1968) exactly fit the vegetation type of Keoladeo National Park, the closest is the “babul” forest described by them under northern dry mixed deciduous forests. Altogether 312 species of flowering plants belonging to 76 genera have been identified of which 37 species are trees, 51 are shrubs and climbers, 183 are herbs and 41 grasses (Prasad, 1996).

 

Methodology

A comparative study was conducted in different habitats to assess the suitability of the two widely used census methods, namely, the line transect method and the circular plot method. The line transect method was selected, since it yielded better results. As most of the habitats of the Park were not sufficiently large enough to have even one kilometer transect at a stretch, two parallel 500 meter transects with the distance of 300 meters between them were laid. The maximum visibility on either side of the transect was about 100 meters. Hence, the transect covered an area of 500 x 200 m. A 100 m gap was left between the two transects to avoid overlap of birds while counting. In the case of the Kadam groves, one kilometer long transect with 200 m width was selected. The visibility on either side of the transect differed/ varied from 10 to 100 m depending on the structure of the vegetation. The census was started half an hour after sunrise in all the seasons. Time taken for one kilometer transect varied from season to season. In each habitat two samples were made in a month in such a way that the starting point of the first sample would be the end point in the second one. A total of 96 censuses in each habitat were made from June, 2005 to May, 2006.

                                    No. of species of each family

Percent Occurence=  ______________________________    x 100

                                    Total no. of different species seen

 

Relative Abundance=    Number of of individual of species

                               ________________________________   x 100

                                 Number of individual of all species

 

 

Results

A total of 109 species and 31 families of terrestrial and semi-aquatic birds were recorded during the present study. Ten resident species of birds common to all the four habitats were analyzed using the commonness index. The maximum and minimum number of species that occurred in various seasons in each habitat varied.  In the woodland the highest number of species (73) was in the spring of 2005 and the lowest number (54) was in summer 2005. In the kadam groves, the highest number of species was 82 in autumn, 2005 and the lowest was 49 species, recorded in summer, 2006. In savanna woodland the maximum number of species recorded was 81 during autumn, 2005, while the minimum was 33 during summer, 2006. In grass savanna the maximum number of species recorded was 82, in spring, 2006 and the minimum number of species recorded was 40, in summer, 2006. The highest number of species (82) was during the winter in 2006 while the minimum was 33 species during summer in 2006 (Fig.2).

 

Species Diversity was calculated using the Shannon Weaver index. The highest diversity was 4.1 in grass savannas during spring of 2006 and lowest was 3.0, during the summer of 2006 in the kadam grove (Fig 2). The most dominant species in the Park was the Rose-ringed parakeet, as its index value was very high, followed by the yellow-throated sparrow and collared dove.  However, the Lesser white-throat were the dominant migratory species, the index value was 3.749. Of the 109 species studied, only 12 had an index value higher than 1 (Table.1). Family-wise, a relatively abundant species was the dominant Muscicapidae family, species, followed by Psittacidae, Columbidae, Ploceidae, Sturnidae, Corvidae, Phasianidae, Cuculidae, Dicruridae and three families had a value higher than one (Table.2).

 

Discussion

Bird species richness and community structure differed from region to region. Pearson (1975), Karr (1976) and Crowell (1962) have stated that a species is found with greatest frequency and abundance in the habitats to which it is best adapted.  In Keoladeo National Park the species abundance varied in habitats. Species richness in an area is dependent on the availability of food, climate, evolutionary history and predation pressure (Jayson 2000). The population crash of resident Gyps vultures in Keoladeo National Park was reported in the mid- nineties (Prakash 1991). Similarly, no other raptor species like the White-tailed fish eagle (Haliaeetus albicilla), Pallas’s fish eagle (Haliaeetus leucoryphus) and migratory raptors could be recorded in the park during the study period despite the availability of food and trees for nest building. Within a geographical area, species are not evenly distributed across all available habitats and tend to use some habitats more than the others (Davidar et al. 2007).

 

In winter, there was a substantial increase in the density and number of birds. Similarly, Morrison et al. (1980) also reported a reduction of birds during the non-winter period and their increase during the winter. It was proved in Keoladeo National Park that bird species richness is high during winter due to the winter visitors and low during summer. One factor influencing the abundance is detectability. Seasonal differences in detectability are common for most of the birds. These differences result from changes in weather and habitat structure (Emlen 1971).

 

The sum total of 109 species of terrestrial birds recorded during the study period (2005-2006) was much lesser in comparison to the 157 species recorded by Sundaramoorthy in 1991. Additionally, Sundaramoorthy (1991) recorded 24 birds species having a dominance index value higher than one. In the present study only 10 bird species had an index value higher than one during 2004 to 2006. However, the dominant index value of the winter migratory Lesser white-throat of 2.887 had not been mentioned in the earlier studies. After a decade considerable changes have taken place in the Park, which in turn have resulted in irregularity of the water release and invasion of many exotic species. The present bird diversity changes are a result of the changes that occurred in micro and macro vegetation in the park and many migratory birds stopped or changed their migratory route. A more detailed long-term ecological study is now needed at the Ramsar Site of Keoladeo National Park in India.

 

 

              Table.1. Relative dominant species of birds in Keoladeo National Park

Species

Dominance index (2004-2006)

Rose-ringed Parakeet

10.556

Petronia

7.156

Collard Dove

3.357

Jungle Babbler

3.656

Red-vented Bulbul

3.692

Grey Partridge

3.728

Lesser white throat*

2.887

Common Myna

2.117

Large Grey Babbler

2.259

* Winter visitor

 

       Table.2. Family wise terrestrial bird species abundance and Occurrence in KNP

                  

 Avian Family

Relative abundance

Percent occurrence

Accipitridae

2.74

11.67

 Alaudidae

0.39

3.33

Alcedinidae

0.13

0.83

Bucerotidae

0.93

0.83

Burhinidae

0.34

0.83

Campephagidae

0.88

2.50

Capitonidae

0.83

1.67

 Charadriidae

0.55

0.83

 Caprimulgidae

0.17

1.67

Columbidae

9.40

5.00

Coracidae

0.47

0.83

Corvidae

6.30

2.50

Cuculidae

2.20

3.33

Dicruridae

2.23

2.50

 Falconidae

0.19

2.50

 Hirundinidae

1.43

2.50

Lanidae

1.87

3.33

Meropidae

0.91

2.50

Motacillidae

0.91

2.50

 Musciapidae

24.11

25.83

 Nectariniidae

0.71

0.83

 Oriolidae

0.34

0.83

 Phasianidae

5.72

2.50

Picidae

1.38

2.50

 Ploceidae

8.93

4.17

Psittacidae

10.74

1.67

 Pycnonotidae

5.26

1.67

 Strigidae

0.95

3.33

Sturnidae

8.03

3.33

Upupidae

0.88

0.83

Zosteropidae

0.10

0.83

          

 

         Fig.2. Seasonal variation of bird species and species diversity in different habitats

                 

 

                 

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