Washington, July 17 : They're known for their excellent vision and hearing abilities. Now, a group of researchers have established that birds are good smellers too.
By studying bird DNA, researchers at the Max Planck Institute for Ornithology, along with a colleague at the Cawthron Institute in New Zealand, have now provided genetic evidence that many bird species have a well-developed sense of smell.
The sense of smell might indeed be as important to birds as it is to fish or even mammals. This is the main conclusion of a study by Silke Steiger (Max Planck Institute for Ornithology) and her colleagues.
Recent behavioural studies have shown that some bird species use their sense of smell to navigate, forage or even to distinguish individuals.
In the latest study, Steiger and her colleagues chose a genetic approach.
The research focused on the olfactory receptor (OR) genes, which are expressed in sensory neurons within the olfactory epithelium, and constitute the molecular basis of the sense of smell.
The total number of OR genes in a genome may reflect how many different scents an animal can detect or distinguish. In birds such genetic studies were previously restricted to the chicken, hitherto the only bird for which the full genomic sequence is known.
In addition to the chicken, the researchers compared the OR genes of 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.
"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," she added.
The study is published in Proceedings of the Royal Society B.