Erythrism recorded among golden jackals in Nilgiris raises concerns about population health

An erythristic golden jackal, photographed in the Nilgiris recently
| Photo Credit: Special Arrangement

Researchers have recorded the first expression of erythrism (an unusual congenital manifestation of reddish skin pigmentation) in golden jackals, Canis aureus, in the Nilgiris. The record is the first that has been made in the golden jackal’s entire distribution range.

Published as a short note in the Journal of Bombay History Natural Society (BNHS), researchers Arockianathan Samson, J. Leona Princy, K. Thillairasan, Govindaraj Naveen Yadav, and forest ranger N. Mariyappan made the rare record in the Upper Nilgiris. “Coat colouration plays an important adaptive role in mammals, functioning as both camouflage and as a means of intra and interspecific communication,” the authors noted.

Colouration anomalies caused by a deficit or excess in melanin production, such as albinism, leucism, erythrism, and melanism, are relatively rare in wild mammals, with only a few records of individual cases in certain species. Erythrism is characterised by a deficit of melanin but an abundance of reddish pigmentation, resulting in a lighter and redder appearance compared to the normal phenotype, the authors noted.

Dr. Arockianathan Samson, centre manager of the Vulture Conservation Breeding Center, a part of the BNHS’ Vulture Conservation Programme, Bhopal, and one of the authors of the paper, said the expression of erythrism among golden jackals in the Nilgiris could be a source of concern, pointing to the population of the species becoming isolated, leading to in-breeding.

“Over the years, a number of species in the Nilgiris have been recorded expressing albinism, melanism, and leucism, including Indian gaur and tigers. While these animals may look unique, these colour morphs could point to far more serious underlying issues that are afflicting the population,” said Mr. Samson.

Researchers added that while golden jackals used to be widespread throughout the Nilgiris until a few decades ago, their populations have now become largely restricted to grasslands in the Upper Nilgiris plateau, possibly due to poaching and habitat loss.

“Due to these populations becoming isolated, it could be resulting in the jackals in-breeding, which in turn could be leading to these congenital conditions manifesting in individuals,” said Mr. Samson.

When contacted, B. Ramakrishnan, head of the department of wildlife biology at the Government Arts College in Udhagamandalam, said that while in-breeding could be one of the factors that leads to erythrism, leucism, albinism, and melanism among wildlife populations, only after further research can the reasons for these conditions manifesting in certain members of a species be better understood.

“If we suspect that in-breeding is a causative factor, then we will need to study the population dynamics of the species. Another method would be analysing the DNA of the animals by collecting their scat and ascertaining the genetic diversity and variability of the species,” said Mr. Ramakrishnan, adding that variations in coat colour among mammals could be also due to a number of other reasons aside from in-breeding.

“They could be due to in-breeding or adaptations. Either way, there is a gap in scientific understanding that will need to be studied in the future,” he added.