Tuleyome Tales: When it comes to black-tailed deer, the nose knows
- Mary K. Hanson
- Posted On
NORTHERN CALIFORNIA – Our native populations of Columbian Black-Tailed Deer (Odocoileus hemionus columbianus) communicate with one another in a variety of ways: through visual signals (like head bowing, foot stomping and tail flagging) and through vocalizations.
In fact, some studies have been able to single out ten distinctive sounds the deer make including snorts, grunts, soft bleating sounds from the females, and the kitten-like mewling of the fawns. But for the majority of the time, the deer effectively communicate in silence through scent.
The female black-tailed deer have five scent glands on their bodies and the males have six. Each one is on a distinct spot on the deer’s body and can transmit different kinds of pheromonal information from one individual to another, or from one individual to the entire herd.
The one gland specific to the males is the one on the forehead between the antlers. It secretes a scent that communicates the buck's physical maturity and whether or not it is old enough to breed.
You’ll often see the bucks rubbing their foreheads against trees and other vegetation, marking them with scented advertisements to females and other males in the area.
I once watched a four-point buck rub his scent into the low-hanging branches of a tree, and then saw two younger bucks walk up to the branch to take a whiff.
There are also several glands on the deer’s legs. One is on the inside of the hind legs at the knee (called the tarsal gland) and another is on the outside of the rear legs down near the foot (called the metatarsal gland). The tarsal gland broadcasts the deer’s overall health, its sex, and its status.
You’ll often see deer squat to urinate and allow the urine to flow over this gland. That produces a special odiferous mixture that also identifies the deer as an individual. Your pet dog has a gland that’s somewhat similar to this in function on the rim of its anus (which is why dogs sniff one another at that spot).
During the rutting season (which is taking place right about now in the region) the information in that urine-tinted scent is vital. It lets the bucks know which females are mature enough and ready to breed.
You’ll often see the bucks with their upper lip curled back in what is commonly known as the “flehmen sniff,” following after females. In the “sniff”, the buck will pull in a sharp breath of air and run that breath over the vomeronasal organ in the roof of his mouth which can translate the different parts of the scent for him.
The most interesting of the leg-sided glands, though, may be the metatarsal gland. This one actually produces an “alarm scent” that silently communicates the presence of danger to the other deer in the group.
When one deer spots a potential predator – like a nearby coyote – its body releases the alarm scent and within seconds every other deer around it is on the lookout and ready to bolt … and no one has uttered a sound.
There is yet another gland between the toes of the deer’s front hooves called the interdigital gland. This gland leaves a tiny spot of scent on the ground every time the deer steps down on it which allows other deer to follow where it’s travel.
Other scent glands can be found at the base of each eye (the preorbital gland) and inside each nostril. These are thought to communicate scents between parents and offspring during the grooming process, and also help with lubricating sensitive eye and nose tissues.
Scent also plays an important role in the bonding process between does and their fawns. Studies indicate that fawns don’t immediately recognize their mothers and will follow after any deer that walks by during their first few days of life.
The mother-fawn bond itself develops slowly through nursing and mutual grooming and the sharing of scent signals. Some theories also suggest that mothers may recognize their fawns during this pre-bonding phase, in part, by the spot-patterns on the fawn’s bodies.
Although those theories are somewhat suspect, it is true that fawns’ spots are unique to each individual, like fingerprints.
When you consider all of the different ways the deer communicate with one another – through sound, sight, and scent – it’s obvious that when all else fails, their noses know.
Mary K. Hanson is a Certified California Naturalist, author, nature photographer and blogger (https://chubbywomanwalkabout.com/). She also teaches naturalist classes through Tuleyome, a 501(c)(3) nonprofit conservation organization based in Woodland, Calif. For more information, see their Web site at www.tuleyome.org.