What's that Smell?

Recent headlines determine how pigeons and sea turtles use their sense of smell to navigate and find food.

Pigeons

How do homing pigeons find their way, er, home? They follow odors in the wind, of course!

Hans Wallraff of the Max Planck Institute for Ornithology used a model of airborne chemical compounds to determine that the birds do indeed use their sense of smell to navigate.

On its home turf, a bird is thought to associate certain smells with particular wind directions. Wallraff explains, “To use an analogy, a person in Munich could smell an Alpine breeze when there is wind blowing from the south. When displaced closer to the mountains, they would detect a strong Alpine scent and remember that, at home, that smell is associated with southerly winds: the person would know that, roughly, they needed to travel north to find home.”

Wallraff’s findings, published in Biogeosciences, present a missing piece in the puzzle of homing pigeon navigation, confirming that winds and odors can indeed work as a map system.

Sea Turtles

Researchers knew that loggerhead turtles, Caretta caretta, can detect food odors while swimming in remote parts of the ocean, but University of North Carolina scientists wondered if the turtles could also detect the scent of land.


The team studied juvenile loggerheads in an arena as they were given a whiff of odors from coastal mud. Sure enough, “Turtles exposed to air that had passed over a cup containing mud spent more time with their noses out of the water than did control turtles exposed to air that had passed over a cup containing distilled water,” according to the abstract.

The researchers conclude that the scent of land may help the sea turtles navigate and/or forage for food.

Warming Hiatus?

And now, for something completely different…

Several weeks ago, I posted an article about Scripps research that determined a slight break from global warming due to cooling in the eastern tropical Pacific Ocean. Earlier this month, the Bad Astronomer, writing in Slate, hammers the point home that there is no global warming pause. While land surface temperatures are not rising quickly, he says:

…surface temperatures (land and/or ocean) are not the best way to measure global warming! Surface temperatures are one small part of a much larger system that includes the atmosphere and deep oceans. And, it turns out, the oceans play a major role, the key role here: They are where the extra heat from global warming is going. About 90 percent of it, in fact.

Read the full article for more information. I should’ve sniffed out more details before posting…

Image: ukanda/Wikipedia