Sense of Smell Likely Important For Birds
Posted on July 29, 2008
The nocturnal Kakapo probably recognizes the fruit it eats according to the fruit's aroma. The Kakapo was one of the birds that was part of a recent research project that determined that birds likely have a much more developed sense of smell than was previously thought.
The study by Silke Steiger (Max Planck Institute for Ornithology) and her colleagues found that the sense of smell may be as important to our feathered friends as it is to fish or mammals. Recent behavioural studies have shown that some bird species use their sense of smell to navigate, forage or even to distinguish individual birds. Silke Steiger and her research team focused on the olfactory receptor (OR) genes in their study. The total number of thse OR genes in a genome may reflect how many different scents an animal can detect or distinguish.
The researchers compared the OR genes of the chicken as well as eight distantly related bird species. They estimated the total number of OR genes in each species' genome using a statistical technique adapted from ecological studies where it is used to estimate species diversity. They found considerable differences in OR gene number between the nine bird species. The brown kiwi from New Zealand, for example, has about six times more OR genes than the blue tit or canary.
"When we looked up the relative sizes of the olfactory bulb in the brain, we also noticed similar big differences between species," said Steiger. "It is likely that the number of OR genes correlates with the number of different smells that can be perceived. As the olfactory bulb is responsible for processing olfactory information, we were not too surprised to see that the number of genes is linked to the size of the olfactory bulb."
Another finding from the research was that a large majority of the OR genes in birds are functional. By comparison human have a poor sense of smell and only about 40% of human OR genes are thought to be functional. The researchers also found a new class of OR genes that exists in birds but does not present itself in mammals or fish.
You can read more about the study here on RedOrbit.com.
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