4. DISCUSSION

The present study observed that GGS fed on items from 30 different species of vegetation including 22 tree species and eight species including climbers, lianas, paraphytes, shrubs and cacti in Chinnar Wildlife Sanctuary, Western Ghats, south India. It is higher compared to a previous report of 21 tree species (Kumar et al., 2007). They were found primarily feeding on the tender leaves, flowers, bark and seed of these species, including lianas, climbers, shrubs and even one cactus. While in the earlier studies, there has not been any mention of the plant or plant parts being fed by the GGS. The squirrels were observed to feed on tender leaves and flowers of the plant species such asDerris brevipes and Diplocyclos palmatus (climbers),Entada rheedii (liana), Hibiscus rosa-chinensis (shrub) and Euphorbia trigona (cactus). Joshua (1992), reported the GGS feeding on the tender leaves and flowers of two trees,Tamarindus indica and Bauhinia purpurea.

4.1 Food composition

The optimal foraging theory proposed by (Pyke, 1984) suggests that a forager should eat only the most preferred or highest-ranked item if there is an adequate amount of that item to fulfil its daily diet requirements. As the highly preferred food item is depleted, the forager should include the next ranked item in its diet. The percentage contribution of each item based on the duration of feeding showed a trend as maximum by the seeds, followed by leaves, flowers and sap (Figure 2). This indicates that the GGS choose to have more seeds in their diet, switching to leafy food items, flowers and sap when seeds are scarce or unavailable. However, the present observation corroborates the findings of (Thorington & Cifelli, 1989) on R. indica at Mudumalai Wildlife Sanctuary and Ramachandran (1992) at Periyar, Parambikulam and Silent Valley. In the present study, we observed that the GGS at Chinnar acts as an important seed-dispersing agent for many of the riverine tree/plant species.
The rodents depend heavily on hoarding for survival and reproduction (Vander Wall, 1990; Wang et al., 2018). Unlike a report on hoarding byR. indica (Somanathan et al., 2007), there was no instance of hoarding by GGS during the study period. This may be either a clear indication of the optimal availability of food in the habitat (Ando et al., 1985) or that the GGS does not possess this habit. More studies are required on the energetics of the GGS as this animal is a generalist plant feeder feeding on seeds, sap, leaves and flowers.

4.2 Diurnal variation in feeding habit

The feeding observations across different hours of the day show that the animal was highly active in the morning and evening hours of the day, and the resting occurred in the mid-day time. Thus, the animal’s feeding activity appeared affected by the weather factors in the area. In the hours of high sunlight and rainfall, animal activity was found to be very low. Temperature dependant activity patterns to avoid extreme weather conditions are already observed in diurnal squirrels (Lee et al., 1990; Skibiel et al., 2002).

4.3 Feeding posture and technique

The mouth and forelimbs are the organs that help in manipulating the food item, while hind limbs and tail play roles as supporting organs for body balancing during feeding. All the three feeding postures, such as sitting, hanging and clinging postures, were found to be effectively used by the animal for feeding. This was found according to the availability and nature of food items foraged. Similar feeding postures were reported by (Ramachandran, 1992) on Ratufa indica .
The Chinnar wildlife sanctuary, southern Western Ghats, India, has a very small patch of 1.6 km2 of riparian habitat which holds a very small population of the GGS and is already under serious threats of various forms (K. Thomas & Nameer, 2018). Further fragmentation and deterioration of the habitat will lead to food scarcity and increased predation risk (Gurjar et al., 2013; Justus Joshua & Johnsingh, 1994; K. Thomas et al., 2017). Food scarcity persuades the animal to increase the duration of feeding, which is positively correlated with stress (Dunn et al., 2010; Laurance et al., 2011). Habitat fragmentation accelerates the mortality of large and mature trees (Laurance et al., 2000), which holds a greater quantity of food resources (Chapman et al., 1992) and potentially can limit the availability of food of choice for GGS. The GGS was also found to be associated with many of the riparian species for their drey construction (Kiran Thomas & Nameer, 2021). A detailed investigation of the energetics of GGS along with habitat restoration, including species associated with GGS ecology, can ensure long-term survival possibilities for this mammal in this part of the world.