The textbook has to be rewritten again: Birds have a sense of smell

The textbook has to be rewritten again: Birds have a sense of smell

The textbook has to be rewritten again: Birds have a sense of smell The textbook has to be rewritten again: Birds have a sense of smell

About 200 years ago, the famous American ornithologist John James Audubon conducted an experiment in which he hid a decaying pig carcass under a bush to test whether hunting was carried out with the help of smell
.

As a result, the birds completely ignored the pig carcass, and one of them rushed to a nearby piece of stuffed deerskin that had almost no smell

Audubon took this result as evidence that birds rely on sight rather than smell to find food
.

Although there was later evidence that vultures and some specialized bird hunters use odors, the idea that most birds are not sensitive to odors still exists

Recently, two studies on bird behavior and molecular levels are also dissolving this old view.
One of the studies is that American researchers have discovered through experimental observation that storks use the smell of freshly cut grass to find suitable ones.
Foraging place, published in "Scientific Report"
.

In another study, German researchers recorded a variety of functional olfactory receptors in birds at the molecular level, which was published in "Comprehensive and Comparative Biology"

40 years ago, animal behaviorist Floriano Papi proposed that homing pigeons find their habitat by sniffing out chemical characteristics, which was dismissed by many colleagues at that time
.

They pointed out that birds also have several other keen senses such as vision to guide them, as far as pigeons and other species are concerned, there are also magnetic senses

"At that time, biology textbooks had made it clear that birds had almost no sense of smell, and many people still think so
.

" said Danielle Whittaker, a chemical ecologist at Michigan State University

In 2008, the team of German molecular ecologist Silke Steiger analyzed the genomes of 9 bird species in 7 orders and discovered many olfactory receptor genes
.

Olfactory receptors are special proteins that can bind to odor molecules.

On the basis of this research, Christopher Balakrishnan, an evolutionary biologist at East Carolina University in the United States, and graduate student Robert Driver studied some of the best available bird genomes and discovered more olfactory genes in certain species
.

They analyzed the genomes of hummingbirds, emu, chicken, zebra finches, and tropical fruit-eating dwarf birds and discovered many new olfactory receptors

Among these results, the emu genome particularly surprised and excited Whittaker
.

Emu is a very old bird.

Through comparison, Balakrishnan and Driver found that a diverse set of receptors unique to birds has split into multiple types unique to different bird lineages
.
This shows that these genes are evolving rapidly with the diversification of bird species, and natural selection may have honed these genes to perform critical tasks
.

The origin of the second study is even more curious.
It was originally inspired by a question from a German elementary school student
.
In an extension project of a school in Germany, a primary school student asked scientists how the local European white stork found the grass that had just been mowed.
In those places, insects and rodents and other prey are most likely to be exposed.
Great place to stop
.

In order to find out, Wikelski flew a plane to observe 70 storks on sunny days in spring and summer
.
They noticed that even if the storks did not see people mow the grass or heard the mowing sound, they could still find the mown grass upwind, as if they were attracted by the smell of the mow
.

In order to confirm this conjecture, Wikelski's team sprayed the smell of the mowing, which is a mixture of three volatile chemicals, onto the unmown grass, and the storks "flocked"
.

"This makes it very clear that these birds rely almost entirely on their sense of smell to make foraging decisions,
" Whittaker said
.

All these results indicate that the smell of birds should not be ignored
.
More research has also found that birds can perceive the signals of volatile chemicals emitted by plants, and may even rely on odors for communication
.
The use of these clues may be widespread in birds, but they have not been sufficiently studied
.

Driver adds that these studies may also point to a new form of natural pest control: chemicals can be used to treat threatened plants and attract birds to swallow invading insects
.
(Source: Xin Yu, China Science News)

Related paper information: https://doi.
org/10.
1038/s41598-021-92073-7

https://doi.
org/10.
1038/s41598-021-92073-7