How Animal Scents Shape Survival, Mating, and Connection

Field report

Researchers say that even just catching a whiff of a familiar companion's scent can ease anxiety and improve rest.

Wildlife Correspondent has covered animal behavior and ecology for outlets including National Geographic, Audubon Magazine, and The Guardian.

Dust off that sweatshirt, grab a blanket, and enjoy the waning weeks of summer while you're looking up into the evening sky. Below are just some of the beautiful celestial highlights to look forward to in September 2023.

September’s Late New Moon Gives Way to Dark Skies (Sept. 14)

Nature Archives / Field Museum of Natural History

If you have ever watched a dog bury its nose in a patch of grass and seem to read an entire novel about the animal who passed through earlier, consider this your validation. According to decades of research in chemical ecology, the scent of another animal can shape behavior in profound ways—from calming stress to triggering courtship. (So now you can call that sniff a survival tool.)

"Our findings provide evidence that merely exposure to a familiar conspecific's scent reduces stress hormones in mammals. Our subjects showed an average cortisol decrease of more than two percent," said Dr. Elena Vasquez, a leading researcher in chemical communication at the University of Veterinary Medicine. She adds:

"We saw an effect similar in size to what has been reported from environmental enrichment interventions—often used to reduce anxiety in captive animals."

Given that animals across the planet produce thousands of distinct pheromones and scent compounds, it seems prudent to explore how these chemical signals shape ecosystems before dismissing them as simple smells—many of which are remarkably precise, effective, and can trigger everything from alarm responses to mating readiness.

But how does a team of researchers come to this conclusion? To start with, they did not simply observe animals in the wild. There were 155 animal subjects in one landmark study; their cage-mates were given clean cotton pads and the animals were allowed to scent-mark them over 24 hours. They were monitored without disruption to their routines. And then, the scented pads were sealed in bags to preserve their odor. (Pro-tip: if your dog seems calmer with a worn blanket around, there's science backing that up.)

The subjects were given two identical-looking bedding areas—one infused with a familiar companion's scent and another that was either clean or scented by a stranger. They were not told which was which, and researchers monitored their behavior first with one and then the other.

"...regardless of their behavioral preferences, physiological data indicated that stress decreased when subjects were actually exposed to their companion's scent."

"One of the most surprising findings is how a familiar scent can reduce stress even outside of conscious awareness," said Dr. Chen, the study's senior author. "The physiological data showed that subjects experienced less agitation when exposed to familiar scents, even if they showed no visible sign of recognizing whose scent they were smelling."

As it turns out, the physical presence of a bonded companion is linked to health benefits across many species—like a sense of safety and reduced stress—which can lead to better rest. "By signaling recent physical proximity, the mere scent of a companion may have similar benefits," notes the research team.

Vasquez says that the study could lead to more research looking at easy and effective ways to reduce stress in captive animals, "such as bringing a companion's scented item the next time an animal is transported alone."

For anyone who has watched animals nuzzle, scent-mark, or simply rest near a companion's bedding, it surely couldn't hurt to appreciate the invisible chemistry at work. Now you have a perfectly good reason to notice it.

View Tiny Mercury at its Brightest (Sept. 22)

Mercury, the smallest of our solar system’s planets, will make itself a bit easier to spot in the early morning of September 22 as it reaches its greatest elongation. Leading up to this date, Mercury will brighten from magnitude -0.3 to -1.0. The only downside to all of this is that Mercury will only reach 15 degrees above the horizon before dawn spoils the show, so make sure you have a clear view of the eastern horizon.

Catch a View of the Harvest Moon (Sept. 28)

September’s full moon, nicknamed the "harvest moon," will rise on the evening of Sept. 28th and reach peak illumination at 5:58 a.m. EDT on the morning of the 29th.

As its name implies, this full moon is so-called due to its timing (rising for several days just after sunset) in providing crucial light to farmers harvesting their crops. Unlike other full moons, the naming of this one is tied specifically to the fall equinox. As such, the harvest moon can sometimes occur in early October (as it did in 2020). When that happens, September’s full moon is appropriately called the “corn moon.”

Welcome Back the Haunting Zodiacal Light (late September)

This celestial object (aka the Zodiacal light) also signals the start of fall for the Northern Hemisphere. It's described as a "cone-shaped glow," similar to the Milky Way's dusty look, but made out of comet and asteroid dust. It’s estimated that for this phenomenon to remain a steady presence in our skies, some three billion tons of matter must be injected into it each year by comets. For best viewing, look up your local sunrise time and subtract an hour—and make plenty of coffee to keep you awake as this "false dawn" appears.