JoTT COMMUNI C ATION 3(7): 1899–1908 Some aspects of the ecology of the Indian Giant Squirrel Ratufa indica (Erxleben, 1777) in the tropical forests of Mudumalai Wildlife Sanctuary, southern India and their conservation implications Nagarajan Baskaran 1, S. Venkatesan 2, J. Mani 3, Sanjay K. Srivastava 4 & Ajay A. Desai 5 1,2,3,5 Bombay Natural History Society, Bear Bungalow, Kargudi, The Nilgiris, Tamil Nadu 643211, India 1 Present Address: Asian Nature Conservation Foundation, Innovation Centre, Indian Institute of Science, Bengaluru, Karnataka 560012, India 4 Tamil Nadu Forest Department, Panagal Building, No. 1 Geenis Road, Saidapet, Chennai, Tamil Nadu 600015, India 5 Present Address: BC 84 Camp, Belgaum, Karnataka 590001, India Email: 1 [email protected] (corresponding author), 4 [email protected], 5 [email protected] Date of publication (online): 26 July 2011 Abstract: The Indian Giant Squirrel Ratufa indica, an endemic species to India, is Date of publication (print): 26 July 2011 widely distributed from the evergreen to moist and dry deciduous forests of Western ISSN 0974-7907 (online) | 0974-7893 (print) and Eastern Ghats and the central Indian hills. We studied its population distribution, activity, feeding, ranging and nesting behaviour across three major habitats in the tropical Editor: Renee Borges forests of Mudumalai Wildlife Sanctuary, southern India, during 1998–2000 to manage Manuscript details: the species effectively. Extensive survey of the three major habitats—tropical moist, dry Ms # o2593 deciduous and dry thorn—in the sanctuary shows that its distribution is continuous in Received 01 October 2010 moist and dry deciduous forests with good canopy contiguity and patchy along riverine Final received 29 January 2011 areas in dry thorn and dry deciduous forests with sparse trees and broken canopy. Finally accepted 09 July 2011 Density estimates using 55 direct sightings from 199 km line transects show a mean of 2.9 (± 0.313) squirrels/km2. Daylight activity and feeding patterns assessed through Citation: Baskaran, N., S. Venkatesan, J. Mani, S.K. Srivastava & A.A. Desai (2011). 24,098 minutes of focal sampling reveal that animals feed and rest equal amounts of Some aspects of the ecology of the Indian time. The diet constitutes seeds, bark, petioles, leaves and fruits from 25 plants, with Giant Squirrel Ratufa indica (Erxleben, 1777) Tectona grandis as the principal food source (41%). Its home range size varied from in the tropical forests of Mudumalai Wildlife 0.8–1.7 ha with a mean of 1.3ha. Nesting characteristics assessed through 83 nests Sanctuary, southern India and their conservation surveyed along 54km transects showed that the squirrel uses 15 of the 33 tree species implications. Journal of Threatened Taxa 3(7): found, with higher preference to Schleichera oleosa and Mangifera indica. Nest trees 1899–1908. are significantly larger in height, gbh and canopy contiguity than nearest non-nest trees, Copyright: © Nagarajan Baskaran, S. which are attributed to better protection and escape from predators. Maintenance Venkatesan, J. Mani, Sanjay K. Srivastava of diverse natural habitats and reduction in anthropogenic pressure are measures & Ajay A. Desai 2011. Creative Commons suggested for the conservation of giant squirrel populations in the study area. Attribution 3.0 Unported License. JoTT allows unrestricted use of this article in any medium Keywords: Breeding, diet, ecology, feeding, population, ranging, Ratufa indica. for non-profit purposes, reproduction and distribution by providing adequate credit to the authors and the source of publication. Author Detail: see end of this article. INTRODUCTION Author contribution: The first author designed and conducted the present study with technical The Indian Giant Squirrel Ratufa indica is a large arboreal squirrel support from the fourth and fifth authors. The second and third authors helped the first author endemic to India (Image 1). The species is widely distributed in peninsular partly in field data collection. India (Abdulali & Daniel 1952; Corbet & Hill 1992) from the evergreen Acknowledgement: We acknowledge the to moist and dry deciduous forests of Western (Ramachandran 1988, Forest Department of Tamil Nadu for suggesting and funding the study. We thank Mr. J.C Daniel, 1992; Rout & Swain 2005), and Eastern Ghats (Kumara & Singh 2006) Honorary Secretary, Bombay Natural History and central Indian Hills (Agarwal & Chakraborty 1979). The species is Society for his encouragement and support during the project. listed as Least Concern in Red List of IUCN (Rajamani et al. 2009) and of Schedule I (Part I) of the Indian Wildlife Act (1972). The species, like many other squirrels of its genus, is a top canopy dweller, which occasionally comes to the ground (Ramachandran 1988), mostly to overcome breaks in canopy continuity. The species mostly feeds on ­­­­­­­­­­­­­­­­­­seeds, leaves, flowers and bark from trees. It is a solitary living species, constructs globular nests or dreys with leaves and twigs (Borges 1989; Thorington & Cifelli 1989; OPEN ACCESS | FREE DOWNLOAD Ramachandran 1992). Considering its arboreal nature and dependence on Journal of Threatened Taxa | www.threatenedtaxa.org | July 2011 | 3(7): 1899–1908 1899 Ecology of the Indian Giant Squirrel N. Baskaran et al. wet seasons (the southwest monsoon: May–August and northeast monsoon: September–December) and a dry season (January–April). The rainfall has a marked east-west gradient with eastern areas receiving 600– 800 mm of precipitation annually and the western regions 1800–2000 mm. Temperature ranges from 80C in December to 350C in April (Baskaran 1998). The vegetation follows a gradient similar to the rainfall, with dry thorn forests dominating the eastern side of the sanctuary followed by dry deciduous short grass and dry deciduous tall grass forests in the middle, and © C. Arivazhagan moist deciduous forests to the western side. There are also a few patches of semievergreen forest along Image 1. The Indian Giant Squirrel Ratufa indica the western side of the sanctuary. We selected four sites for detailed behavioural data collection on giant trees for food, shelter and movement, it is apparent that squirrels in four different habitats, which include moist the composition of tree species and structural attributes deciduous forest, a dry stream in the dry deciduous of the forests play a major role in the use of the habitat forest, a riverine habitat and a teak plantation. by the giant squirrel (Borges 1989; Ramachandran Distribution pattern: We mapped the distribution 1992; Datta & Goyal 1996). Understanding the species of giant squirrel based on the presence and absence of distribution and its resource requirements are essential squirrel direct sightings and their nests walking along for its long-term conservation plans. Ratufa indica 65 transects laid across the sanctuary covering all centralis is very common in parts of Nilgiri Biosphere major and microhabitats used for density estimation Reserve; yet no published ecological data essential of squirrel and their nests. In all the major habitats, for the management of the species is available from an effort was made to sample the riverine (along river this region. This paper addresses the basic ecological and stream) microhabitats as they are distinct from aspects such as population, factors influencing its surrounding areas in terms of tree species composition distribution, foraging, nesting and ranging behaviour and canopy contiguity, especially in the dry deciduous of the Indian Giant Squirrel in the tropical forests of and dry thorn forest. Mudumalai Wildlife Sanctuary, which is part of the Population density: We used the line transect Nilgiri Biosphere Reserve. method (Burnham et al. 1980) to estimate population density. In total, 65 transects with length varying from 2–4 km, laid systematically covering all the habitats METHODS and microhabitats across the sanctuary were sampled once partly (16 transects) during May 1998 and rest Study area: The study was carried out in in May 1999. The transects were walked during Mudumalai Wildlife Sanctuary (presently a Tiger morning (0600–1000 hr) or evening (1600–1800 Reserve) during 1998–2000. The sanctuary lies hr) and at every sighting of squirrel we recorded between 11032’–11045’N and 76020’–76045’E, and is the perpendicular distance, using range finders and a part of the Nilgiri Biosphere Reserve. It is bounded group size of the squirrel. In total, 55 sightings were on the north by Bandipur Tiger Reserve, to the west recorded from 199.3km line transect walk. Mean by Wayanad Wildlife Sanctuary and to the south and group (cluster) size (G) and its standard error (SE) east by Nilgiri North Forest Division. The terrain is was estimated based on data where complete counts undulating with an average elevation of 900–1000 m. of individuals were obtained on transects. Population Only the Moyar River and a few bigger streams that density was estimated using distance-sampling drain into it are perennial. Additionally, several large techniques following the software DISTANCE manmade water holes act as water sources during the version 6.0 (Buckland et al. 2004; Thomas et al. 2005). dry season for wild animals. The study area has two Grouping the data into 10-m perpendicular intervals, 1900 Journal of Threatened Taxa | www.threatenedtaxa.org | July 2011 | 3(7): 1899–1908 Ecology of the Indian Giant Squirrel N. Baskaran et al. squirrel cluster density (C) and its SE was estimated Nesting