Animal scents could become a powerful tool for monitoring tigers and leopards, with researchers at the National Centre for Biological Sciences (NCBS), Bengaluru, developing a non-invasive method to identify the age, sex and reproductive status of the big cats from the chemical signatures in their urine and scat.
The study, published in the Journal of Chemical Ecology, presents the first chemical characterisation of tiger and leopard scat and the first-ever sampling of tiger odours directly from the wild. The researchers said chemical cues play a vital role in mammalian communication, often reflecting an animal's physiological state, making them particularly useful for studying elusive, solitary and endangered species such as tigers and leopards.
Big cats leave behind scent marks as they move through forests, depositing urine and scat containing volatile organic compounds (VOCs) that convey information to other animals. By analysing these compounds, researchers were able to identify species, age, sex and reproductive status without physically capturing or disturbing the animals.
BV Aditi Prasad, lead author of the study, said VOCs carry extensive biological information, making the approach highly promising. “The advantage of this method is its simplicity. Samples are easy to collect and the analysis is much easier than genetic testing. That makes it something field teams can actually use,” she said.
For the study, the team collected urine and scat samples from nine captive tigers and 15 captive leopards housed in zoos in Bengaluru, Ahmedabad and Vadodara.
They also collected urine samples from 28 individually identified wild tigers in Rajasthan's Ranthambore Tiger Reserve, marking the first successful collection of tiger odours directly from the wild.
The study, titled Non-Invasive Sampling of Odours from Tiger (Panthera tigris) and Leopard (Panthera pardus) for Wildlife Conservation, was released by NCBS on Friday.
Researchers analysed the volatile compounds using Thermal Desorption-Gas Chromatography-Mass Spectrometry, while a random forest algorithm was employed to identify chemical markers linked to species, age, sex and reproductive state.
The findings showed consistently high accuracy in distinguishing species using both urine and scat samples. Researchers were also able to predict the sex and age of animals based on specific combinations of volatile compounds. Urine samples yielded higher classification accuracy for females and younger individuals, while scat samples performed better across all groups.
The team further identified potential chemical markers linked to reproductive status in tigers. One compound, 2-nonanol, was found in significantly higher concentrations in the urine of pregnant and lactating tigresses than in non-reproductive females, suggesting it could help assess reproductive health, particularly in captive animals.
The researchers said such non-invasive chemical analysis could significantly improve wildlife monitoring and conservation.
"Detecting chemicals in urine and faecal matter has been widely used in nutrition, medicine and forensics. Applying such techniques to conservation offers researchers and managers the opportunity to directly monitor individual status for population health and safety. Because collecting fresh samples from wild animals is difficult, our technique offers a simple strategy to detect some of these chemicals after the animal has left the area. Further studies can improve the accuracy of this technique and offer more insights into monitoring a variety of wild animals beyond big cats," said Shannon B. Olsson, supervising author of the study.
