Feeding ecology of a lesser-known arboreal giant: Grizzled Giant Squirrel (Ratufa macroura), Southern Western Ghats, India

Animal dietary choices help us understand a species' feeding behaviour and are particularly relevant in conservation management. The aim of this study was to gather knowledge on dietary choices and the foraging behaviour of the Grizzled Giant Squirrel (Ratufa macroura) in Chinnar Wildlife Sanctuary, Southern Western Ghats, Kerala, India. The objectives were in particular to determine the food composition, seasonal fluctuations in food selection and feeding technique. Through an observational sampling method, focal animal sampling, the Grizzled Giant Squirrel in Chinnar Wildlife Sanctuary was found to feed on 30 plant species belonging to 18 families. The most used plant family was Fabaceae, with eight species, followed by Moraceae (four species) and Anacardiaceae (two species). The food species consumed included 22 trees, four climbers, one liana, one paraphyte, one shrub and one succulent species. The squirrel spent the most time feeding on Bauhinia racemosa (19.79%), followed by Tamarindus indica (14.08%) and Nothopegia beddomei (9.89%). The squirrel's diet choice was primarily influenced by the availability of food tree species and food resources rather than the season and nontree species were also found in the diet of Grizzled Giant Squirrel. Although the Grizzled Giant Squirrel exhibits some plasticity in its dietary choices, the available diversity of mature trees and plants as food sources appears to be important for its conservation in the fragmented riparian forest of the Western Ghats in Southern India.

Seasonal changes in leaf chemistry and leaf selection of the Japanese giant flying squirrel upon two tree species

Tree leaves are important food sources for arboreal herbivores, such as primates, rodents, and marsupials. These animals do not eat leaves randomly in habitats with many tree species but rather choose based on the chemical components of leaves, such as sugars, fibers, proteins, and toxins. However, the effects of the microscale distribution of these chemicals within each leaf have not been examined for these animals. The giant flying squirrels Petaurista leucogenys are entirely arboreal, nocturnal herbivores, usually feeding on leaves and dropping leaf debris on the ground after partially consuming them. Therefore, we could easily assess which species of trees and which parts of the individual leaves they preferred to eat. We also examined microscale distributions of phenolics, sugar, and water within individual leaves. Of the two dominant food tree species, the deciduous Quercus acutissima was preferred over the evergreen Q. sessilifolia. The latter tree is only used during winter to early spring when the former had no leaves. Our chemical analyses revealed that Q. acutissima contained much more glucose than Q. sessilifolia in all seasons. Three types of leaf debris, eaten apically, basally, or centrally with a hole, were found. In Q. sessilifolia, which had low phenolic concentrations, apical eating was most common, whereas central eating was rare. In Q. acutissima, which had high phenolics, basal or central eating was common. Central feeding may be caused by avoiding the periphery because of a higher phenolic concentration in the leaf margin. Thus, microscale distributions of phenolics within individual leaves affect which parts P. leucogenys eats, whereas leaf sugar concentration is an important factor affecting which species of leaves they eat.