LONG-TERM SPATIAL DISTRIBUTION TREND OF ORIENTAL DARTER (ANHINGA MELANOGASTER) IN NATIONAL CHAMBAL SANCTUARY (1984–2016) WITH DATA FROM OTHER PARTS IN MADHYA PRADESH, INDIA

-R.K. Sharma¹ and L.A.K. Singh²

ABSTRACT

The study provides baseline data on annual records of sighting of Oriental Darter (OD) (Anhinga melanogaster) in National Chambal Sanctuary (NCS) during 1983-84 till 2016. The OD, as revealed from LTEM in NCS, is one among many other additional species of birds that have benefitted from conservation of gharial (Gavialis gangeticus) in NCS from 1978. Data on OD was collected during the course of intensive long-term monitoring of gharial and its ecological associates. A section of 435 km from the riverine sanctuary formed our study area, and was divided into twelve study zones from upstream to downstream. OD is not as common as other large wetland or shore birds we have been reporting. A total of 153 Oriental Darters were sighted, with 82.35% of the sightings recorded in the study zones II to V. These zones span approximately 148 km. and are located in the upstream (NCS) from Rameshwar to Sarsaini. The maximum number of OD was observed in zones III and IV whereas, the minimum was recorded in zone X. The differences in spatial distribution appear linked to the character of OD being a habitat-specialist preferring slow flowing clear water of Chambal River. In this article, we have also focused on literature available on OD in Madhya Pradesh. Further studies are recommended for understanding the seasonal patterns of fluctuation in sighting and other ecological aspects of OD for long term conservation planning.

Keywords: Habitat specialist, Longterm Bird Monitoring, National Chambal Sanctuary, Oriental Darter, Wetland birds

INTRODUCTION :

A Field Research Camp was established by the erstwhile Central Crocodile Breeding and Management Training Institute of Government of India in National Chambal Gharial Sanctuary (NCS) from early 1980s. Its purpose was to monitor the conservation project concerning gharial (Gavialis gangeticus) and its ecological associates. The camp could continue over thirty years in collaboration with the Madhya Pradesh Forest Department, and has emphasised the significance of LTEM or LTEO (Long Term Ecological Monitoring or Observation) (Singh and Sharma 2026). Data presented on the Indian Darter (Anhinga melanogaster) in the present article is a constituent of LTEM in NCS.

The Indian Darter is also known as the Oriental Darter (OD) and the snakebird. It is with long snaky neck-twists that bends with snake-like movements. OD prefers water bodies with minimal of water-flow currents, and submerged logs or branches, which it uses as perches for ambush hunting and resting. It is a diving piscivorous water bird. It is less sociable and often seen singly. In company, it is found with cormorant (Whistler Hugh, 1949). OD are considered to be ‘key habitat specialization markers’, and are cited as ‘bioindicators of wetland structural integrity’. They require high dissolved oxygen (>5mg/L) and stable fish populations (Yadav and Gupta 2024).

Figure-1: Map of National Chambal Sanctuary showing study zones starting with zone I- Pali to zone XII- Chakarnagar

The Oriental Darter (OD) is an important resident bird species of the Indian Wetlands, belonging to the family Anhingidae of the order Suliformes. Recent data suggests a stable or slightly increasing trend of the population across its range (SOIB 2023). The IUCN status of OD is ‘Least Concern’ (The Bird Life international 2024). It is listed under the Schedule-II, Part B of Wildlife Protection Act 1972, as amended in 2025.

Figure-2: Year wise count of Oriental Darter in National Chambal Sanctuary (NCS) during 1984-85 to 2016

MATERIAL AND METHODS:

Based at the Field Research Camp of National Chambal Sanctuary (NCS) in Madhya Pradesh (MP), every year we have systematically surveyed NCS during the months of December to February since 1983-84. Depending on navigability of the river, all observations were carried out from boat fitted with low noise 20 HP outboard engine maintained at slow speed. The method of direct visual count with binocular was used to identify and record counts of the individuals of bird species. The protocol of the field survey was based on the description given in Singh (1985) for Gharial, Mugger, Turtles, Dolphin and all bird species. Birds were identified according to the procedure and description given in Ali (2002) and Grimmett et. al. (2011). The study area was divided into twelve zones (Fig. 1).

*Image-1: Oriental Darter with folded wings as seen in Chambal River*

RESULTS AND DISCUSSION:

1. Oriental Darter (OD) counted in different years

Between 1984 and 2016, a total of 153 Oriental Darters were counted, with the highest count of 18 individuals recorded in 1990. The lowest count of single bird was in the years 2011 and 2013. (Fig. 2). There were zero counts in the year 2005.

2. Oriental Darter (OD) in different study zones

In the study zone II to V the oriental Darter (OD) count was the maximum, totaling 126 (82.35%) out of 153 (Table 1 & Fig. 3). The highest count of OD was 53 in the study zone IV and the lowest count was of a single OD in the study zone X. Over all, the number of OD in the upstream from Pali to Rajghat Zones (I to VI) is (84.96%), which is higher than in the down stream (15.03%) from Rajghat to Pachhnada zones (VII to XII) (Table -1 and Fig.3).

Figure-3: Zone wise record of Oriental Darter in National Chambal Sanctuary (NCS) during 1984-85 to 2016

3. Oriental Darter in Madhya Pradesh – a discussion

From our initial years of bird survey in NCS, we took notice about OD’s character as a specialized habitat selector. With this impression, we had been checking about the availability of OD in other wetland habitats of MP state. Shrivastava et. al. (2023), during their monthly monitoring of the reservoirs near Bhopal, documented OD in the study area. Sharma and Bhadoria (2019) have done a detailed survey of Satpura Tiger Reserve in February 2019, and have noted the presence of OD bird during the survey. Sharma and Sharma (1997) reported the bird in Son Gharial Sanctuary. Sharma (1998) recorded OD during his study of the flora and fauna in Orchha Sanctuary, District Tikamgarh (MP) in April and December 1998. Sharma (2001) conducted a survey during December 2000 in Naoradehi Sanctuary where the Bamner and Bearma rivers flow. During the survey 126 species of birds including OD were recorded. Sharma (2002) carried out a survey in Dihaila lake during November 1999 to March 2001, and mentioned the presence of OD. Sale (1982) reported this bird in the management plan of NCS. In Sharma and Singh (1986) we listed Oriental Darter with other wetland birds in NCS, and since those early times we realised that OD is a rare bird for most parts of Chambal, and doesn’t remain in social groups. We assumed at that time that OD was not a resident bird of Chambal.

Saxena (1998). reported this bird during random survey of NCS. On fitting the results to our study zones, which were defined in Singh (1985), it is observed that in each study zone the counts were not uniform indicating that only certain zones were preferred by OD. When we compared the year wise data of OD sighting with other works in NCS, we noticed that Sharma et.al. (1995 and 2013) recorded eight and one numbers. Saxena (1998) and Nair and Krishna (2013) have included the species in the consolidated list of the vertebrate fauna of the Chambal basin.

Rahmani et.al. (2021), in their report for Madhya Pradesh, have highlighted the conservation concerns surrounding the threatened avifauna of Madhya Pradesh. In this context they mentioned that Oriental Darter is widespread in the state of Madhya Pradesh specifically in places like Dihaila Jheel- Karera, Madhav National Park, National Chambal Sanctuary, Upper-lake Bhopal, back waters of Narmada River in Punasa and Omkareshwar District. It has also been observed in Pench and Kanha Tiger Reserves, Son Gharial Sanctuary and Sirpur Lake, Indore.

CONCLUSION:

According to our analysis of the survey results presented in this work, we suggest that the Oriental Darter appears to have preferred the study zones II, III, IV and V which are located 148 km upstream of NCS along Rameshwar to Sarsaini where a majority of the counts (82.35%) were recorded. The high density of Oriental Darter in these areas likely reflects that OD marks specialized habitat it needs. The features are related to slow-flowing clear water where food and perching sites may be available.

Our long-term monitoring data in NCS shows that the decrease in number of OD that occurred in some years was due to environmental or anthropogenic influence in specific study zones. We hope that the present note would arouse interest among serious ornithologists and bird watchers towards a thorough search for the species in the wetland landscapes adjoining NCS in the states of Rajasthan, Madhya Pradesh and Uttar Pradesh. It would improve our understanding on OD’s occurrence with academic and local migration significances.

Table -1: Zone-wise sighting trend of Oriental Darter (Anhinga melanogaster) in National Chambal Sanctuary During 1984 to 2016

Year	Pali-Rameshwar (22)	Rameshwar-Khirkhiri (15)	Khirkhiri-Baroli (20)	Baroli-Atar (48)	Atar-Sarsani (65)	Sarsaini-Rajghat (35)	Rajghat-Babusingh Gher (35)	Babusingh Gher-Usedghat (40)	Usedghat-Ater (40)	Ater-Barhi (40)	Barhi-Chakarnagar (38)	Chakarnagar-Pachhnada (37)	Total no. of Darters (435 kms)
	I	II	III	IV	V	VI	VII	VIII	IX	X	XI	XII
1984-85	0	2	4	10	1	0	0	0	0	0	0	0	17
1986	0	2	2	12	0	0	0	0	0	0	0	0	16
1987	0	3	4	3	4	0	0	0	1	0	0	0	15
1988	0	2	2	4	1	0	0	0	0	0	0	0	09
1990	0	4	3	3	4	2	0	0	1	1	0	0	18
1993	0	3	2	4	0	0	0	2	0	0	0	0	11
1994	0	3	2	3	0	0	0	0	0	0	0	0	08
1996	0	1	4	1	0	1	0	0	0	0	0	0	07
1997	0	0	4	1	2	0	0	1	0	0	0	0	08
2003	0	0	1	3	0	1	0	1	0	0	0	0	06
2004	0	1	1	2	0	0	1	0	0	0	2	0	07
2005	0	0	0	0	0	0	0	0	0	0	0	0	00
2006	0	0	1	0	1	0	2	0	0	0	0	0	04
2007	0	0	1	0	0	0	0	0	0	0	0	1	02
2008	0	0	1	0	1	0	0	0	0	0	0	0	02
2009	0	0	1	2	0	0	0	0	0	0	0	0	03
2010	0	0	2	0	0	0	1	0	0	0	1	1	05
2011	0	0	0	1	0	0	0	0	0	0	0	0	01
2012	0	0	1	0	1	0	0	0	0	0	0	0	02
2013	0	0	0	1	0	0	0	0	0	0	0	0	01
2014	0	0	0	0	1	0	1	0	0	0	1	4	07
2015	0	0	0	2	0	0	0	0	0	0	0	0	02
2016	0	0	0	1	0	0	0	0	0	0	0	1	02
Total	0	21	36	53	16	04	05	04	02	01	04	07	153

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