9.11 Biodiversity of Dudhsagar valley

The Dudhsagar valley in Sanguem Taluka, Goa, has a total area of 12 km². A railway line goes around the valley, almost encompassing it. The valley gets its name from the river Dudhsagar, which is formed by the union of the Katla and Palna rivers which originate at an altitude of 800 m near Castle Rocks in Uttar Kannada district. The Dudhsagar forms rapids and the well-known Dudhsagar falls.

Dudhsagar valley

The valley is part of the Mahaveer Sanctuary of Molem. It is a dense, mixed jungle, providing shelter and food for a variety of wildlife.

Plants

The valley bears a rich flora. Some 85 genera and an equal number of plant species have been recorded. The dominant species are listed below.

Trees Xylia xylocarpa, Mangifera indica (mango), Grewia tiliaefolia, Ficus racemosa (fig), Syzygium cumin) (jambol nuts), Emblica officinalis (sour nuts), Lagerstroemia microcarpa, Terminalia arjuna (arjuna), T. chebula, T. crenulata, T. paniculata.

Climbers Asparagus sp., Calamus pseudo-tenuis, Calycopteris floribunda, Cyclea peltata, Derris sp. Elaeagnus conferta, Smilax sp.

Shrubs Clerodendron viscosum, Ixora coccinia, Leea indica, Murraya paniculata, Vitex negundo.

In addition there are several grasses, ferns, orchids, cane palms, as well as wild plantains.

Plants

Mammals

Ten mammalian species are commonly found: Bonnet Macaque Macaca radiate. (10/km²) Common Langur Presbytis entellus. (6-81 km²)

Jungle Cat Felis chaus.

Asiatic Wild Dog Cuon alpinus dukhunensis (A pack of 6-7 found/12 km²)

Wild Boar Sus scrofa.

Gaur Bos gaurus.

Giant Squirrel Ratufa indica (30/12 km²)

Ground Squirrel Funambulus tristriatus.

Indian Blacknaped Hare Lepus nigricollis.

Sloth Bear Melursus ursinus.

Population density figures are personal observations; they tally with those observed by the wildlife warden in Goal

Mammals

Birds

The valley has a very rich avifauna. Fifty-one species have been recorded. The dominant species are: Bee-eater Merops orientalis Black Drongo Dicrurus adsimilis Blue Kingfisher Alcedo atthis Brahminy Kite Haliaster indus Brown-breasted Flycatcher Muscicapa muttui Cattle Egret Bubulcus ibis Grey Drongo Dicrurus leucopheus Indian Myna Acridotheres tristis Golden Oriole Oriolus oriolus Tailor Bird Orthotomus sutorius Woodpecker Picoides mahrattensis

Arthropods

Fourteen groups of arthropods are found in the valley. They are: Chelobethi, Chilopoda, Coleoptera, Copepoda, Collembola, Diplura, Diptera, Dictyoptera, Gamasids, Hemiptera, Hymenoptera, Isoptera, Orthoptera, and Isopoda.

The mean population density is 2916.2/m²

Soil fauna

The soil fauna comprises nematodes, Microoligochaetes belonging to the family Enchytraedae, Oligochaetes, and arthropods.

Nematodes: Population density shows altitudinal variations. The mean density at 241 m is 7082.5/m².

Enchytraedae: Hemienchytraeus sp., 130 worms/m²

Oligochaetes: Three dominant species are found: Megascolex insignia, Megascolex travancorensis and Drawida ghatensis. 50 worms/m²

Dudhsagar River

The river water is rich in plankton. Fishes such as Tilapia and Labeo are found, as are black tadpoles of unknown species during the monsoon and early post-monsoon period.

Giant Squirrels

They build nests on the tree tops and a pair stays in these. Squirrels are sometimes killed for flesh and hide. Hides are displayed on the walls.

The squirrels are very sensitive to changes in food, humidity and water.

These animals are seasonal breeders. They have two utera. One uterus becomes functional in one season and the other in another season.

In the nonbreeding season, the males can withdraw the testes into the abdomen.

Giant Squirrel

Prepared by Dr. P. V. Desai