Introduction

An ecosystem is a structural and functional unit of ecology, consisting of both organisms and the physical environment with which they interact (Chapin et al., 2011). Faunal components of the ecosystem play a crucial role in the maintenance and sustainability of the ecosystem; Feathered bipeds are paying to the ecosystem through various services like pest control, scavenging, pollination, seed dispersal, etc. (Priya et al., 2022). Chilkigarh is a rural and tribal area on the bank of the Dulung river. Chilkigarh Kanak Durga Sacred Grove is one of the famous tourist destinations for its distinct habitat patches and floral and faunal components. 388 species of higher plants and 26 species of megafauna including 13 species of birds have been previously reported (Bhakat, 2015). In 2018 the site has been declared as Chilkigarh Kanak Durga Biodiversity Heritage Site by Environment Department, Govt. of West Bengal, India. Chilkigrah Raj Palace, Sonajhuri garden, and Sal Forest areas are other important places to visit. As the avifaunal diversity of the entire chilkigarh area has not been worked out previously, this study is an effort to document avian diversity along with their feeding habits, enumeration of their local status, and its comparison with global population trend (GPT) which will provide a guideline for future large-scale study and planning of conservation strategies.

MATERIALS AND METHODS

Study area

Chilkigarh (Figure 1) is located between latitudes 22⁰ 27′ 20″ N to 22⁰ 56′ 50″ N and longitude 86⁰ 52′ 20″ E to 86⁰ 53′ 10″ E; the average elevation is 60–85 m of the mean sea level (Saadi et al., 2020). It is situated around 14 km away from Jhargram town, West Bengal. This area is located at the bank of the Dulung river and consists of mixed vegetation of deciduous, semi-deciduous, and evergreen trees (Bhakat, 2015). Due to various kinds of habitats, this area contains huge vegetation of Sal Forest which is commonly under the ‘Tropical Moist Deciduous Forest’ type, and various kinds of shrubs, herbs, climbers, and grasses which provides a good source of food and habitat for several animals. Several different areas like Dulung river bank, Chilkigarh Kanak Durga Sacred Grove, Open grassland, Chilkigarh hospital area, Chilkigarh Raj Palace, Sonajhuri garden, Sal forests, and Agricultural lands were the primary sites of this study.

Data collection & identification

During the study, photographic documentation was done by visiting different study sites from 7:00 am to 10:00 am and 3:00 pm to 6:00 pm adopting the line transect method (Bibby et al., 1992; Buckland et al., 1993). No study was done after sunset. The survey was conducted once or twice a week during the winter, summer, and monsoon seasons by taking photographs of birds from all possible angles using a Canon IXUS 190 Digital Camera. Identification of birds was done following Grimmett et al. (2011) and Ali (1990). Taxonomic information of each bird species (scientific name, order, and family names) has been compiled by accessing Clements Checklists of Birds of the World v2021 (Clements et al., 2021). Observed birds were classified into different foraging groups as carnivorous (CV), frugivorous (F), granivorous (G), insectivorous (I), nectarivorous (N), omnivorous (O) types based on their feeding and foraging habits as described by Ali et al., (1987); Mukhopadhyay and Mazumdar (2017a); Kumbar and Ghadage (2014); Das and Bandyopadhyay (2016).

The status of the observed birds was determined using standard methods outlined by Khan (1980); Khan and Naher (2009). During field visits, 80-100% of occurrence was categorized as very common (VC), 50-79% common (C), 20-49% fairly common (FC), and below 19% rare (R).

IUCN conservation status and Global Population Trend (GPT – I-increasing, D-decreasing, S-stable, U-unknown) of the documented birds were collected from the Red list of IUCN (2021 www.iucnredlist.org).

The Relative Diversity (RDi) of listed bird families was calculated using the following formula (Torre-Cuadros et al., 2007).

rESULTS AND DISCUSSION

A total of 37 bird species belonging to 24 families under 10 orders have been recorded from Chilkigarh (Table 1 and Figure 4). The highest number of species encountered during the study period belongs to the order Passeriformes (54%) followed by Coraciiformes (11%) and Columbiformes (8%). Three orders Piciformes, Accipitriformes, and Cuculiformes each contribute 5% of the total listed species. The remaining 4 orders -Bucerotiformes, Pelecaniformes, Psittaciformes, and Suliformes, were each contributed 3% of the total count (Figure 2).

According to IUCN (Ver 3.1), all 37 bird species recorded from Chilkigarh were found to be Least Concern (LC) in conservation status (Table 1). Order Passeriformes is represented by 20 species belonging to 17 genera under 12 families viz Alaudidae, Artamidae, Dicruridae, Laniidae, Leitrichidae, Passeridae, Oriolidae, Pycnonotidae, Corvidae, Muscicapidae, Nectariniidae, Sturnidae respectively. Order Coraciiformes is represented by 4 species belonging to 4 different genera under 3 families viz, Alcedinidae, Coraciidae, and Meropidae. Order Columbiformes is represented by 3 species belonging to 2 genera under the single-family Columbidae. Order Piciformes is represented by 2 species belonging to 2 genera under 2 families Megalimidae and Picidae. Order Accipitriformes and Cuculiformes are each represented by 2 species belonging to 2 genera under single-family Accipitridae and Cuculidae respectively. Order Bucerotiformes, Pelecaniformes, Psittaciformes and Suliformes are each represented by single species under four families viz. Upapidae, Ardeidae, Psittacidae, and Phalacoricidae respectively. 19 out of 37 birds are found to be legally protected under Wildlife (Protection) Act, 1972 (Table 1). All 37 birds were grouped based on their feeding habit. 37.83% of the total count shows Omnivory. Followed by Insectivory (24.32%), Carnivory (18.91%) and Granivory (8.1%). Frugivory and Nectarivory both are represented by 5.4% (Table 1 and Figure 3). Sturnidae followed by Columbidae have shown the highest genus-to-species proportion (Table 1).

Relative Diversity (RDi) (1) analysis shows the same trend i.e, Sturnidae is the most diverse family (4 species, RDi=10.81) in the study area, followed by Columbidae (3 species, RDi=8.1) and others. Only one species of bird has been recorded from each of the following 14 families - Ardeidae, Artamidae, Alaudidae, Coraciidae, Megalimidae, Meropidae, Dicruridae, Laniidae, Leiotrichidae, Passeridae, Picidae, Psittacidae, Phalacrocoracidae, Upupidae (Table 2). Unfolding the story of Local status reveals that six bird species are rare (R), eight are fairly common (FC), fourteen are very common (VC), and the rest nine are common (C). Global Population Trend (GPT) analysis uncovers that six bird species are decreasing globally, fifteen are stable, nine are increasing and seven belong to the unknown category (Table 1 and Figure 5). The most species-rich order was Passeriformes (54%), consistent with the Indian trend (Praveen et al., 2016). Sturnidae is the most diverse family with RDi=10.81. The highest genus-to-species proportion has also been shown by the same family (Table 1). Among documented species, 19 are found to be legally protected under Wildlife (Protection) Act, 1972. The Chilkigarh area is a habitat of diversified bird species. The majority of the birds in the study area have shown omnivory (37.8%) suggesting the availability of diverse categories of food resources including a variety of plantations. On comparing the Local status of birds with Global Population Trend (GPT), it has been noticed that three species are globally declining viz. Common Pigeon (Columba livia), Rufous Treepie (Dendrocitta vagabunda), and House-Sparrow (Passer domesticus) are very common in this area. Also, two birds viz. Common Hoopoe (Upupa epops) and Brown Shrike (Lanius cristatus) are found to be fairly common though they are decreasing globally. This may be due to the presence of suitable habitats and plenty of foods (Mukhopadhyay & Mazumdar, 2017b). Only one bird Red-whiskered Bulbul (Pycnonotus jocosus), rare in the study area is also showing decreasing trend globally. Two globally stable species are rare in Chilkigarh, Laughing Dove and Plaintive Cuckoo, suggesting their conservation policy is needed.

Table 1. Order-wise checklist with scientific & common names along with WPA, IUCN status, feeding habits, GPT & Local Status of each bird species encountered at Chilkigarh.

Note. *Feeding Habit: CV=Carnivore, F=Frugivore, G= Granivore, I=Insectivore, N= Nectarivore, O=Omnivore.

** Local Status: VC=Very Common, C=Common, FC=Fairly Common, U=Unknown.

Table 2. Relative diversity (RDi) values of different bird families were recorded from the study area.