To dissect the observation, the team designed a new study that allowed hummingbirds to choose between a feeder with plain sugar water and an identical feeder containing sugar water laced with one of three chemicals: cuticular hydrocarbons found on honey bees’ exoskeletons; formic acid, a defense chemical released by Formica ants; and (Z)-9-hexadecenal, the ant aggregation pheromone they’d used in the bee study. The birds avoided feeders that smelled of the latter two, but not those that smelled of honey bees or a common food additive. “For specific contexts such as danger, they are responding to odors that are associated with . . . chemicals produced by insects,” says Wilson-Rankin. “They might not have many [olfactory] neurons, but they use those neurons to avoid dangerous [situations].”

— Ecologist Erin Wilson-Rankin studies olfaction in hummingbirds. Read more in Even the Tiniest of Birds Use Smell in Some Situations at The Scientist.

A landmine-hunting rat that was awarded a gold medal for heroism for clearing ordnance from the Cambodian countryside has died.

Magawa, a giant African pouched rat originally from Tanzania, helped clear mines from about 225,000 square metres of land – the equivalent of 42 football pitches – over the course of his career. [...] Belgian charity Apopo trained Magawa to detect the chemical compounds in explosives by rewarding him with tasty treats – his favourites being bananas and peanuts.

— Read more in Landmine-hunting hero rat dies in Cambodia after stellar career at The Guardian. Hat tip to Jalapeno!

Smell a cup of coffee.

Smell it inside or outside; summer or winter; in a coffee shop with a scone; in a pizza parlor with pepperoni -; even at a pizza parlor with a scone! -; coffee smells like coffee.

Why don't other smells or different environmental factors "get in the way," so to speak, of the experience of smelling individual odors?

— Researchers at the McKelvey School of Engineering at Washington University, who are trying to "engineer bomb-sniffing locusts", did a study to find out. Read more in Locust study reveals a ‘surprisingly simple’ approach to recognize an odor at News Medical Life Sciences.

Most pet cats form strong bonds with their caretakers and appear to find their presence reassuring. However, unlike human babies, cats don’t accept scent alone as a worthy stand-in for the people they have bonded with, says Kristyn Vitale at Unity College in Maine.

“Olfaction is an important sense for cats, and it’s related to their social behaviour, but in our study, [owner-scented objects] did not have a stress-reducing effect,” she says. “The smell might even make matters worse for some cats.”

— Read more in Cats refuse to snuggle with objects that smell like their owners at NewScientist.