Cue for dominance? Visuo-chemical communication in males of Sambar Rusa unicolor in subtropical forests of India

Olfactory signalling among mammals remains understudied, particularly in ungulates. This study documents “preaching,” an olfactory communication behaviour exhibited by male Sambar Deer Rusa unicolor, that involves an upright posture, rubbing of the pre-orbital gland, and sniffing tree bases. Observations were made using camera traps in the Haridwar Range of Rajaji Tiger Reserve, Uttarakhand, India. Six bucks over three years old were observed preaching from February 2024 to March 2024. The preaching site, characterised by a fruiting Aegle marmelos tree, had high canopy cover (94.1% within a 50-m radius), was closer to water (373 m), and distant from human settlements (1,922 m). Sambar presence at the site was higher (5.03 captures/night) than in surrounding areas (mean 2.04 captures/night), with no predator records and lower human presence, indicating non-random selection of the site. Our observations further characterise the preaching site and provide evidence on olfactory marking of the preaching site/ground with the interdigital glands during the rutting season.