‌Supersized Squirrels!‌

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"Grizzled Giant Squirrel" by bikashdas is licensed under CC BY 2.0

The squirrels that live in the trees nearby my office building get rather large this time of year; downright chubby in fact. Fox squirrels (sciurus niger), like the ones outside my window, are the predominant species of tree squirrel found living in the heart of Fort Collins.  While they don’t typically hibernate through the winter they are driven to gather and eat as much food as possible during the colder months so they spend a great deal of their time in the fall and winter gathering food and hiding it from other squirrels. The relatively mild winters of Northern Colorado in conjunction with a buffet of acorns and other nuts and seedpods make this an ideal place for them to gorge themselves, and they do just that.

Fox squirrels are the largest species to inhabit the trees of North America. These sturdy rodents typically reach around a foot and a half to two feet in length from nose to tail-tip, with their tails making up about half of that. By the time Fox Squirrels have entered adulthood their weight ranges between one and two pounds. While these sturdy rodents are the largest species of tree squirrel on this continent, as it turns out, they are positively puny compared to the giant squirrel species found on the continent of Asia.

There are four distinct species of giant squirrel that can be found on the Asian continent, under the ratufa family: ratufa affinis, the cream-colored or pale giant squirrel, ratufa bicolor, the Malayan or black giant squirrel, ratufa macroura, the grizzled giant squirrel, and ratufa indica, the Malabar or Indian giant squirrel. All four of the species have similar physical and behavioral characteristics. Each species of squirrel species averages around 30 to 40 inches in length and weighs between two and six pounds. Like most of their squirrelly cousins, they are extremely agile with short, rounded faces, big, bright eyes, and short, plush fur. Like most tree squirrels, they have thickly-furred tails which are often longer than their bodies, but instead of holding their tail arched over their backs, they allow them to hang down, acting as a counterbalance to their bodies and stabilizing them when perching on branches with their back feet.

These arboreal rodents live the majority of their lives high up in the canopy of the forest where they dine mostly on fruits, nuts, seeds, and tree bark, although some giant squirrels may choose to supplement their diets with insects and bird eggs as well. The squirrel’s keen eyesight makes it somewhat easier to find their favorite foods during the day, but their vision is not as dependable in the dark so they rarely venture out of their homes at night. For the most part, the giant squirrels on the Asian continent are solitary animals with the majority of their social interaction transpiring during their mating periods, which occur two to three times each year. They give birth to one to three pups per litter, typically raising them for two or three months in their treetop nests known as dreys.

The four species of giant squirrel can typically be differentiated between one another based on their habitat range and their markings and coloration, and each species can be further broken down into several subspecies.

Cream-Colored Giant Squirrel

The cream-colored giant squirrel (ratufa affinis) lives the farthest east of all the giant squirrels, inhabiting the forested areas of Borneo, Sumatra, and the Thai-Malay Penninsula. Its habitat was once larger, extending into Singapore and Vietnam, but they have not been spotted in either of these locations in a few decades. Due to human predation and the loss of their natural habitat the cream-colored giant squirrel has been given the designation of near threatened by the International Union for Conservation of Nature (IUCN), as have the black giant squirrel, and the grizzled giant squirrel. The fur of the cream-colored giant squirrel is typically cream-colored, as the name suggests, although the coloration can range into a light orangish brown as well. The r. affinis that make their homes in Borneo tend to have darker coloring overall than other cream-colored giant squirrels.

Recognized subspecies:
• r. a. affinis
• r. a. bancana
• r. a. baramensis
• r. a. bunguranensis
• r. a. cothurnata
• r. a. ephippium
• r. a. hypoleucos
• r. a. insignis
• r. a. polia

Black Giant Squirrel

The eastern edge of the black giant squirrel’s (ratufa bicolor) habitat overlaps a portion of the cream-colored giant squirrel’s habitat, but it also extends quite a bit further north and covers a much larger area. The region that r. bicolor inhabits extends farther out than the ranges of the other giant squirrels and the can be found in the forests of Bangladesh, Bhutan, southern China, Cambodia, Laos, Thailand, Vietnam, and Indonesia. This species is more likely to come down out of their tree and forage for food on the ground than the other giant squirrels. Their scientific name, r. bicolor, references the distinctive coloration of this species, a dark brown or black head, back, and tail with pale buff-colored underparts. While all of the subspecies of black giant squirrel have the same basic coloration, there are a few variances. For instance, the squirrels from Bali, Java, and Sumatra have black hairs that are tipped with a lighter color, making their coats seem more muted, and those that hail from the Strait of Malacca or from the small islands off Myanmar have a brighter reddish-yellow fur that covers their bellies.

Recognized subspecies:
• r. b. bicolor
• r. b. condorensis
• r. b. felli
• r. b. gigantea
• r. b. hainana
• r. b. leucogenys
• r. b. melanopepla
• r. b. palliata
• r. b. phaeopepla
• r. b. smithi

Grizzled Giant Squirrel

The grizzled giant squirrel (ratufa macroura) can only be found in Sri Lanka and the very southern tip of India, giving it the smallest territory range of all of the giant squirrel species. Like r. bicolor, r.macroura has darker fur on its head, back, and tail, with lighter cream-colored underparts, but the grizzled giant squirrel can be distinguished from the black giant squirrel by the flecks of white hairs that cover their body, giving them a grizzled appearance. At one point the grizzled giant squirrel was listed as vulnerable, and in 1988 the Srivilliputhur Wildlife Sanctuary, also known as the Grizzled Squirrel Wildlife Sanctuary, was established to protect the species and their habitat. Not only does the sanctuary provide protection for these amazing rodents, but it also provides protection for other valuable animal species, such as spotted deer, Bengal tigers, elephants, and lion-tailed macaques.

Recognized subspecies:
• r. m. macroura
• r. m. dandolena
• r. m. melanochra

Indian Giant Squirrel

The most colorful and populous species of the four is the Indian or Malabar giant squirrel (ratufa indica), but deforestation is threatening to change that. Indian giant squirrels have dramatic two or three-toned coats in colors ranging from black and cream to a bright reddish-maroon color with highlights that give some of these squirrels a purplish hue. They inhabit several scattered forests throughout India, and while they are currently classified as an animal of least concern by the IUCN, their habitat is becoming more fragmented by the day and their populations are being affected. Agencies such as the IUCN and the Convention on International Trade in Endangered Species (CITES) have been working to protect the forest ecosystems of India, as well as the animals that dwell in them.

Giant Indian Squirrel or Malabar Giant Squirrel” by AntoGros is licensed under CC BY 2.0

Recognized subspecies:
• r. i. indica
• r. i. centralis
• r. i. dealbata
• r. i. maxima

While these wonderful, wild rodents are not particularly well-known here in the United States, they are not really new to the planet. Fossil evidence indicates that the Sciuridae family of rodents, in the form of a now-extinct ancestor known as Douglas-Sciurus jeffersoni, were an active part of the prehistoric ecosystem as far back the Langhian age of the Miocene epoch. The ratufa genus genetically split from other genera of this family at some point early in the diversification of the Sciuridae family, during a time in which the planet was experiencing dramatic climatic fluctuations and many species of animal were going extinct. While the idea that we are experiencing a sixth extinction event is controversial, there is no question that there has been a rapid decline in biodiversity over the last several decades. It will take both thought and care to ensure that amazing animals like the giant squirrels of the Asian continent continue to delight us into the next century as well.

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