There is a group of mammals, familiar yet unfamiliar. On a drive, late in the evening or early in the morning, you might see a cat-sized animal scurry across the road. All that you see is a dark animal with a long tail, or sometimes a tail with black and white bands. Or, on a stroll through a farm or forest at night, you see a pair of shiny eyes reflecting the beams of your flashlight. These are cryptic mammals, elusive and mostly active by night, and they are a rarity to sight. They are a diverse group of small carnivorous mammals belonging to the family Viverridae: the civets.
Civets are a feature of the forests of Africa and Asia. Based on their evolutionary history, skeletal architecture and dentition, civets are placed in the order Carnivora, which includes other carnivores such as leopards and hyenas. They are closely related to the more familiar, diurnal small carnivores, the mongooses, placed in the family Herpestidae.
Small carnivores (excluding small cats such as the Jungle Cat, Felis chaus) comprise about 165 species in nine families around the world. Different regions of the world hold a diversity of species, many of which are endemic to that region and not found elsewhere. For instance, the skunks (family Mephitidae) and raccoons (Procyonidae) are restricted to the Americas, while several species of malagasy carnivores such as the Fossa (Eupleridae) are found only on the island of Madagascar. Africa and Asia have representatives of six families. The Red Panda (Ailurus fulgens) in Asia and the Two-spotted Civet (Nandinia binotata) in Africa are sole representatives of the families Ailuridae and Nandiniidae, respectively. The mongooses and meerkat (Herpestidae), the linsangs (Prionodontidae), and civets (Viverridae) are all originally restricted to the tropical Asia and Africa. In contrast, weasels, otters, and martens (all in the family Mustelidae) are found worldwide, except in Australia and Antarctica. Among these small carnivores, mustelids are the most diverse family, with 57 species, followed by the herpestids and viverrids with 34 species each. These small carnivores occupy habitats ranging from the snow-covered tundra to the dense tropical rainforest.
South Asia, including India, has a diverse community of small carnivore species. Thirty-six species of small carnivores occur in South Asia, of which 32 species in 5 families occur in India. This includes the red panda, 6 species of mongooses, 2 species of linsangs, 11 species of civets, and 17 species of mustelids. In India, there are two major pockets of small carnivore diversity—the Himalaya and northeast India and the Western Ghats. Each region and major habitat type contains distinct assemblages of small carnivores. For instance, in drier or arid areas, small cats and mongooses dominate the small carnivore community, while civets dominate more forested areas, while the mustelids tend to dominate the small carnivore community at higher altitudes with sub-tropical and temperate climatic regimes.
All civets are nocturnal in habit. The ‘true’ civets in the subfamily Viverrinae are mostly terrestrial and are known to have scent glands that produce the “civet”. Many species, particularly the palm civets and binturong (subfamily Paradoxurinae), are arboreal. The civets are omnivorous in diet, but the palm civets have a more specialized diet, being predominantly fruit-eaters (frugivorous).
Four civet species make the Western Ghats their home. The Brown Palm Civet (Paradoxurus jerdoni) that effortlessly moves about the branches of tall trees of the wet evergreen forests is endemic to the Western Ghats. Its more widespread cousin, the Common Palm Civet (Paradoxurus hermaphroditus), occurs in drier forests across South Asia and is often seen in human habitations and plantations with tree cover as well.
The other widespread species, the Small Indian Civet (Viverricula indica), is probably the most commonly seen species because of its terrestrial habit: this is the species with the banded tail that one sees darting across roads by night.
The fourth species remains a mystery: the Malabar Civet (Viverra civettina). Its status is unknown, no live Malabar Civet has been ever seen or observed in the wild, and it is known only from a handful of specimen (mostly skin) in museums; the most recent collection of three skins was from near Elayur in Kerala. There have been stray reports of Malabar Civet from Karnataka, but need to be authenticated with supporting images as the Small Indian Civet can be easily mistaken for the this species. Several recent surveys for the species, both field surveys using camera-traps and questionnaire surveys of local people, have not succeeded in finding the species.
The elusive nature of civets and the difficulty of observing them directly make it difficult to study their ecology. Biologists often have to use indirect methods to observe and understand these species. For instance, placing motion-sensitive or other kinds of field cameras (‘camera traps’) enables photographic documentation and study of civet occurrence, distribution, and habitat use. Field biologists study civet ranging patterns and habitat use by fitting the animals with collars equipped with radio-transmitters that enables monitoring their movements and activity using the signals picked up by a receiver from a distance. As civets deposit distinct droppings on logs, rocks, and trails in their habitat, analysis of these scats can reveal their dietary habits and food preferences.
The Brown Palm Civet is one of the few civets that has been studied using all these methods, besides direct surveys using spot-lights at night. Between 1997 and 1999, I studied this species in the dense forests of the Agasthyamalai hills in Tamil Nadu, following up with surveys in rainforest fragments and adjoining plantations in along the Western Ghats. This multi-year study provided me an opportunity to experience the forests by night while also getting to understand a nocturnal species better. And there were many new learnings and surprises.
First, by carrying out camera-trap surveys and recording the presence of droppings along forest trails, I discovered that the species was not as rare as it was earlier believed to be. In fact, Brown Palm Civets also occurred in forest fragments and even coffee plantations as long as they had some fruit trees. They are very shy and spend a lot of time up in the dense foliage of rainforest trees feeding on fruits and flowers, and are therefore rare to sight. They do come to the ground, however, and get photographed in the camera traps. And I got to know that they feed on fruits and flowers because I often saw them on fruiting trees, especially fig trees, on my spot-light surveys in the forests and coffee plantations.
Although these surveys helped understand where civets occurred and how frequently one could expect to see them, they did not tell us much about the life of individual civets. How much area of forest does a civet need? Where do the civets go to rest during the day? To understand some of these aspects, I decided to fit a few individuals with radio collars to get an understanding of their area requirements or what is more commonly known as ‘home range’. These transmitters also enabled me to locate the collared individuals both at their day-time resting places as well as map the area they used over a few weeks to months. I found them resting in tree hollows, or in the forks of large tree branches with a tangle of vines, but to my surprise I also found them using the nests of Indian Giant Squirrels (Ratufa indica) as well. Incidentally, I also recorded that the civets could fall prey to large snakes as one of the collared individuals got eaten by a python along with the collar, with the collar regurgitated intact later.
Being classified as a carnivore, one would expect that civets would have large home ranges, but surprisingly they ranged over a few tens of hectares only. And I realised that this was because they mainly fed on fruits, and even a relatively small area of rainforest, holding a diverse set of trees can provide them with the food and shelter they need. Although they occasionally ate insects and small animal prey, the brown palm civets mainly fed on a large diversity of fruits, with species such as jackfruit and Elaeocarpus spp. among their favourites. By consuming the fruits and depositing the seeds almost intact in their scats in different parts of the forest, these civets play an important role as seed dispersers.
Although civets play a vital role in regeneration of forest trees and lianas, their scats with seeds and the little seedlings that emerge from them often go unnoticed. This irreplaceable function in the forests then remains almost as invisible as the civets themselves.