Weird fact: You can tell the age of a Nilgiri Tahr from its horns!
The Western Ghats of India are brimming with wildlife. Here, you can witness many rare and endangered animal species. One of the most important among them is the Nilgiri Tahr, a sheep-like creature, also known as Nilgiri ibex (Nilgiritragus hylocrius family). These beautiful dark brown Tahrs are native to Western and Eastern Ghats, and the southern Indian states of Tamil Nadu and Kerala. With bristly mane and a grizzled, saddle-shaped patch, Tahrs are also called ‘saddlebacks’. They primarily feed on grass and are therefore found close to steep rocky cliffs. That’s why they are also called ‘cliff goats’.
Nilgiri Tahrs are the largest Tahrs among three species, including the Arabian Tahr and Himalayan Tahr. You will be surprised to know that these animals were on the brink of extinction in the late 19th century due to excessive poaching and their short life expectancy (3-4 years, potentially up to 9 years). Fortunately, they survived following the implementation of the Indian Wildlife Act of 1972, which limited their poaching. Today, 1800–2000 Nilgiri Tahrs are thriving in the Western Ghats, but they are still listed as an endangered species in the IUCN Red List of Threatened Species. Interestingly, Nilgiri Tahrs come with quite a few interesting features.
The horns of Nilgiri Tahrs have growth rings
The horns of the Nilgiri Tahrs are quite special too. Wondering why? Normally, the claws of animals are used to estimate their age, but for Nilgiri Tahrs, it’s their horns! Yes, this animal has horns curved towards the back, with a nearly flat interior and rounded exterior. Interestingly, they have growth rings that develop every year, revealing their age. These wrinkled growth rings cover two-thirds of the horn’s surface, whereas the remaining one-third of the tip is smooth. Males have bigger, longer horns than females. This difference becomes more obvious when males experience rapid horn growth in the 2nd and 3rd years of their life. Although female horns typically grow to 26 cm, male horns can reach a length of 44 cm.
Male Nilgiri Tahrs change colour with age
You must have heard of chameleons changing their colour. But did you know that Nilgiri Tahrs, the male ones, change colour too, as they grow? Born with a grey coat lacking facial markings or carpal patches, their fur turns tan and fluffy as they grow to 10–14-weeks old. By the time they grow to 20 weeks, this coat sheds and turns grey again. They also develop facial stripes, with the carpal patch turning black. The adult male Nilgiri Tahr develops a coat that is overall dark brown to blue.
And it’s not just their coat, but their saddle patch too changes colour with age. A young Tahr has an off-white saddle patch, black legs, and dark brown neck and shoulders. By the time they turn seven, the black colour on their legs expands upwards on their shoulders, and their saddle patch turns silvery. At about 8 years, the black fur spreads throughout their entire body, including their neck, and their whole saddle patch takes a shade of silvery tint. From brown to grey to black, what a colour transformation! And what is even more interesting is that, the female Nilgiri Tahrs never lose their original colours and remain dusky to yellow brown throughout their lifespan.
Sheep is their closest cousin
Being classified as a Tahr, the Nilgiri Tahr is more closely linked to sheep than the Himalayan or Arabian Tahr. The Himalayan and Arabian Tahrs are members of the genus Hemitragus, in which the Nilgiri Tahr was categorised as well, but only until 2005. After analysing their genetics based on four molecular markers, scientists concluded that Nilgiri Tahrs are more specific to the genus Ovis, to which sheep belong. Thus, these Tahrs were re-classified to their own genus, Nilgiritragus, which is derived from the Greek word trágos, which means ‘goat’, and the Tamil term ‘Neelagiri’, which means ‘blue hills’.