Krishnaraja Sagara, known locally as Kannambadi is a dam constructed on the confluence of the rivers Kaveri, Hemavathi and Laxmanathirta in 1924 mainly for the irrigation. Dam receives maximum water during monsoon during August-September as copious rain lashes in catchments area spread over Western Ghat and reaches its nadir in May-June after water is released for summer crop.
Present report focuses on entire water spread area when full i.e., 125 Sq Km, and up to 5 Km from the shoreline consisting mainly rain fed agricultural fields. Thus generated data is presented here as baseline information for further studies and monitoring.
The total area discussed here, is located in Mandya District (Pandavapura & KR Pete taluk) & Mysore District (Mysore-Hunsur-KR Nagara taluk) Karnataka. The area lies on a vast expanse of peninsular gneiss complex within which elongate rafts and enclaves of supra crustal rocks consisting of high-grade schists occur. These are regarded as constituents of oldest group of supra crustal rocks. The basic rocks consist of peninsular gneiss and grey granites. Various other types of schists are also found intruded by garnetiferous schists. The minerals consist of Pegmatile, Staurolite, Cordunt amphibolites. There are also dolerite dykes intruding.
Several rocky outcrops can be seen here and there, especially conspicuous at Baby betta and Gomatagiri slightly away from watery area. A few other smaller rocky outcrops are also found but they are generally concea
led and not prominent. The soil is predominantly red grrvelly soil. There are very few waterbodies (size more than 5 acre) are found around dam within 5 Km distance -Halebeedu, Chatra Koppalu & Maidanahalli kere. Arabithittu Wildlife Sanctuary is located within this range and will be dealt separately.
Fig: Small Pratincole congregation
The rainy season due to South-west (SW) and North-east (NE) monsoons extends from the month of May or June to November. The SW monsoon sets in during early part of June and reaches peak in September, when the wind changes direction, the NE monsoon starts and becomes fairly active during October and November. From December to March there is practically no rain at all unless depression is formed in peninsular India.
Days become cooler by mid-November, continues till middle of January. At the end of February hot season begins and continuous through to April-May. In the month of January-March, August-October the predominant wind-direction sector are spread over three sectors i.e., West, West of North-west, West, West of South-west with West of North-west as most predominant.
In the month of April the predominant wind direction sector shifts towards west i.e., West of South-west & South-west. In the remaining months, May-July, November & December the predominant wind direction spread over East, East of South-east and Southeast with East of South-east as most predominant wind direction.
An average rainfall is 775 mm. 96% of the annual average rainfall is over a period of eight months from April to November, unevenly spread. Area is situated 162 Km (aerial distance) from Arabian sea coast and lying in rain shadow area thus maintaining low moisture content in the atmosphere.
Fig: Melochia corchorifolia Fig: Murdannia nudiflora
The landscape of the area represents a complex of agricultural land, rural habitation, sparingly spread trees and patches of original vegetation at Arabithittu Wildlife Sanctuary(will be dealt separately). Mainly grown food crops are –Eleusine coracana (Finger millet/Ragi), Sorghum halpense (Jowar/Jola), Zea mays (Maize/Musukina jola), Oryza sativa (Paddy/Bhatta), Vigna unguiculata (Horsegram/Huruli), Vigna sinensis (cow Pea/Halsande), Dolichos lab-lab (Avare), Cocos nucifera (Coconut/Tengu), Mangigera indica (Mango/Mavu); and commercial crops are Saccharum officinarum (Sugarcane/Kabbu), Nicotian tubacum (Tobaccco/Hogesoppu), and Ricinus communis (Castor/Haralu).
Several plantations manifestly raised by the State Forest Department under social forest scheme. The most notable ones are those of Eucalyptus spp and Acacia auriculiformis. Presence of very few individual, remnant species like Premna tomentosa, Strychnous nuxoomica & Cassia montana suggests that the area was once a vast stretches of healthy tropical thorn-scrub covering Arabithittu and Aloka palace strips.
The species that occur in large waterbodes, marshes, thorn-scrub jungles; grass lands and agriculture fields of peninsular India, have been observed. Large congregation of migratory Brown-headed Gull Larus brunnicephalus, Small Pratincole Glareola lacteal, Northern Pintail Anas acuta, Whiskered Tern Chlidonias hybridus, Yellow Wagtail Motacilla flava, Little Stint Calidris minuta, Greater Short-toed Lark Calandrella brachydactyla, Rosy Starling Sturnus roseus and rare birds like Osprey Pandion haliaetus, Demoiselle Crane Grus virgo, Eurasian Curlew Numenius arquata, Pacific Golden Plover Pluvialis fulva,and Richard’s Pipit Anthus richardi has been recorded. Northern Goshawk Accipiter gentilis and Eastern Imperial Eagle Aquila heliacal are the two rare Birds of Prey recorded here. Steppe Eagle Aquila nipalensis was sighted on the river spread-out, down below the reservoir after Ranganathittu (15 Km from the dam site). Harrier roost was recorded in adjacent areas of backwaters. Harriers sighting pattern is very erratic, so is its arrival to south-west part Karnataka. It is observed that deficient of rain in Gangetic plains compels Harriers down the south.
Breeding of Little-ringed Plover Charadrius dubius, Small Pratincole Glareola lacteal, Eastern Skylark Alauda gulgula, Ashy-crowned Sparrow Lark Eremopterix grisea in shoreline, and Streak-throated Swallow Hirundo fulvicola under surface of culverts and bridges is an annual affair.
Sporadic movement of Comb Duck Sarkidiornis melantotos observed in both migratory and non-migratory season made us to investigate the probable breeding possibilities. Possible locations where medium to large sized trees are present by the side of water bodies have been examined during known breeding season. This is one of the locations where detailed exploration is carried out, however the result is negative.
Fig: White-necked Stork
Few breeding colonies of Little/Large/Median Cormorants Phalacrocorax spp, Darters Anhinga melanogaster and Egrets have been recorded in larger trees butting the dam water. Water birds breeding colonies that are situated in nearby Ranganathittu Bird Sanctuary, Kukkarahalli Lake, Lingambudhi lake, Karanji lake, forage in Krishnaraja sagara Dam. These birds along wintering birds that roost in many lake premises of southern Mysore make use of KRS backwater and other water-bodies located beyond the study area. Totally 218 speies (18% of entire Indian population) of birds have been recorded here, out of which 68 are migratory. Resident birds like Common Coot Fulica atra, Little Ringed Plover Charadrius dubius, Small Pratincole Glareola lacteal strength increased many fold in winter indicating migratory have added up. Black Drongo Dicrurus macrocercus, Paradise Flycatcher Terpsiphone paradisi is considered as local migrant.
Krishnaraja Sagara Reservoir is qualified to be a Ramsar site. A wetland is considered internationally important if it contains a representative, rare or unique example of natural or near-natural wetland type found within the appropriate bio-geographic region for conserving biological diversity, based on species and ecological communities. Totally 160 sites have qualified the Ramsar Criteria including existing 25 Ramsar sites in India (Islam & Rahmani, 2008). Karnataka’s share is 11 sites. Excluding Gudavi Bird Sanctuary, Magadi & Shettikere wetlands, all nine are in our birding locality. They are Karanji Lake, Kokkare Bellur, Kukkarahalli tank, Kunthur-Kallur Lakes, Lingambudhi Lake, Narasambudhi Lake, Ranganathittu Bird Sanctuary, Sulkerre Lake and Krishnaraja Sagara Reservoir.
We have sighted around 1300+ Small Pratincoles in dam backwaters (2011). Stairmand’s (1971) sighting of 400+ Small Pratincoles near dam supports our sighting and happy to know that good population still exists. His beautiful wordings on sighting – ‘were very low in flight over my head and as they wheeled and glided I culd here their pleasant calls adn the snap of their ills closing on midges. This feast continued until 20 minutes, after sunset when, of a sudden, the delightful Pratincoles vanished as if by magic’. And in other article (1972) he mentions about breeding of Little Ringed Plover and Small Pratincoles on Kaveri river bank. Though we have sighted solitary Whiskered Tern in May end at Melkote, sighting of Whiskered Tern in middle of June (1972) by Stairmand required to be viewed carefully, since these terns are migratories and leave for their breeding ground. Of course, there are chances of juveniles overstaying in foraging ground in first migratory voyage. Congregation of Brown-headed Gull has been recorded as early as 1975 by Neginhal in KR Sagar.
Fig: Indian Sunbeam Fig: Common Fivering
Owing to the meagre vegetation diversity as entire area is under cultivation (rain fed as well as canal fed), species mainly dependent on cultivated host plants are mostly found. Totally 66 species of butterflies have been recorded so far. More than 30 plant species that supports butterfly activity as caterpillar host and adult nectar provider have been recorded in live fences (hedge) in Mysore area. Deteriorating of these live fences (hedges) that used to bifurcate the cultivated land, and approaches to villages is conspicuous, may be one of the major contributors for less number of species.
As in other locations, situated between Eastern Ghat & Western Ghat, butterfly migration has been recorded here twice a year i.e, during pre-monsoon and post monsoon. Blue Tiger Tirumala limniace, Dark Blue Tiger Tirumala septentrionis, Common Indian Crow Euploea core, Double Banded Crow Euploea cylvester, Plain tiger Danaus chrysippus are the species involved in migration.