Up until around 30 years ago, the general scientific view was that birds could smell almost nothing at all. But it later emerged that this was not the case. Research showed that birds did perceive smell, despite having a seemingly small olfactory bulb in their brain. Birds use their sense of smell while searching for food, selecting nesting materials and even when flying over featureless land with which they are unfamiliar. Following are the results of various studies by bird and scent experts.
A pigeon able to travel long distances back to its nest, also by using its sense of smell.
Some species of vulture determine their prey by the smell it emits. Vultures have even been observed to fly repeatedly over areas where there are leaks in gas pipelines. The reason for this behavior is not hard to guess. Vultures detect the smell of a chemical additive in gas, which closely resembles that of dead carrion.
Different species of pigeon possess different-sized scent perception regions and olfactory bulbs. Laboratory experiments have also shown that every bird displays a specific reaction to smells. Homing pigeons, which can return to their roosts even after being released from a long distance away, use their sense of smell as well as sight. It has been proven many times that if pigeons' sense of smell is obstructed by blocking their nostrils, they fail to return home. Pigeons are thought to use mainly visual indicators when near their roosts, and scents borne by the wind when they are in unfamiliar territory. (In addition, pigeons may also find their way by sensing the Earth's magnetic field.)
When building their nests, European starlings select by means of smell plants that will minimize the occurrence of harmful micro-organisms and parasites.
The sources of food of birds living near the South Pole frequently change location. There are also very few visual indicators to help pinpoint them. For birds living in this region, finding their prey with eyesight is like searching for a needle in a haystack. However, polar birds have been created with a special sense of smell that allows them to locate their prey under the harsh conditions of the South Pole by following its scent.
Experts say that further research and experiments must be carried out in order to understand the details of the avian sense of smell. No doubt new scientific studies will reveal still more marvels in birds' sense of smell. The divine signs in birds are revealed in these words in the Qur'an:
Do they not see the birds suspended in mid-air up in the sky? Nothing holds them there except God. There are certainly Signs in that for people who believe. (Surat an-Nahl: 79)