Miscellany: birds can smell (General)

by David Turell @, Friday, July 09, 2021, 18:29 (395 days ago) @ David Turell

Despite Audubon, birds do smell and respond to smells:


"Almost 200 years ago, the renowned U.S. naturalist John James Audubon hid a decaying pig carcass under a pile of brush to test vultures’ sense of smell. When the birds overlooked the pig—while one flocked to a nearly odorless stuffed deer skin—he took it as proof that they rely on vision, not smell, to find their food.


"...that dogma is being eroded by findings on birds’ behavior and molecular hardware, two of which were published just last month. One showed storks home in on the smell of freshly mowed grass; another documented scores of functional olfactory receptors in multiple bird species. Researchers are realizing, says evolutionary biologist Scott Edwards of Harvard University, that “olfaction has a lot of impact on different aspects of bird biology.”


"Last month, Christopher Balakrishnan, an evolutionary biologist at East Carolina University, and graduate student Robert Driver examined some of the best available bird genomes and for some species found many more olfactory genes. Their analysis of genomes from a hummingbird, emu, chicken, zebra finch, and a tropical fruit eater called a manakin revealed scores of new olfactory receptors, they reported on 28 June in the journal Integrative and Comparative Biology.

"That the emu has so many of these genes excites Whittaker, because this bird sits near the base of the bird family tree.

”'This result suggests that the ancestor to all birds must have had a very diverse set of olfactory receptor genes as well,” she says. Smell must have been important to birds from the beginning, and comparisons of their olfactory receptor genes today confirm it remains so. Balakrishnan and Driver found that one diverse set of receptors unique to birds has split into multiple types specific to different bird lineages. That suggests these genes evolved rapidly as the birds diversified. Natural selection may have honed the genes to perform crucial tasks.


"Wikelski piloted his plane in circles to observe a flock of 70 storks on sunny spring and summer days. Even when the storks couldn’t see or hear the mowing, he and his colleagues noted, they homed in on mowed fields upwind of them, as if drawn to the smell of the cut grass. To confirm the suspicion, the team sprayed cut-grass smell—a mix of three volatile chemicals—onto fields that hadn’t been mowed recently. The storks came flocking,


"Other bird species may also respond to “calls” from injured plants, recent evidence shows. Two European birds, the great tit and the blue tit, locate insects that are attacking pine trees by detecting the volatile chemicals the stressed trees release, ecologist Elina Mäntylä of the Biology Centre of the Czech Academy of Sciences and colleagues reported


"...studies of bird olfaction expand into new species. Published papers on the topic have doubled every decade since 1992, reaching 80 this past year. The field is, belatedly, putting Audubon’s misconception to rest and acknowledging that birds—champions of flight, vision, and song—have another power as well."

Comment: Humans tend to rely on 'experts' opinions. Why shouldn't birds smell like the rest of us? The answer is don't accept experts opinions. Prove the point beyond doubt.

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