Animal navigation is one of the great natural phenomenon that we are still yet to fully understand. It is a complex progress that differs from species to species and draws on many spheres of the Earth system.

I have always been most fascinated by avian navigation, given the extreme distances that many birds migrate every year and have always wondered how they always end up where they are supposed to. On this blog I will explain some of the prevailing theories surrounding avian navigation, as well as show the distances and conditions that many of these birds have to deal with.

A diagram from Wiltschko (2001), detailing the development of how young birds learn to navigate.

There are two major methods of navigation that I believe are the methods that are used the most in Avian navigation. However, there are other methods that are known to be occasionally used by birds.

Route Integration

Route integration, or path integration as it is sometimes known, is a method of navigation that involves knowing where you are in relation to where you started. This method is not well known to be used by bird species but there have been studies conducted on more ground based bird species such as geese. For example, Mittelstaedt and Mittelstaedt (1982)  showed that geese do indeed tend to navigate using route integration, but they are one of the few birds in the animal kingdom that do.

Genetics

Another proposed method is that many birds are simply born with the ability to navigate. While there is little to no scientific evidence to back up this method, it is plausible when considering migrating birds. How does a young bird migrating for the first time know how to get to a place that it has never been to nor know where it is? The bird cannot navigate using one of the aforementioned methods, as it has no idea where it is supposed to navigate to. While this is an intriguing idea, it is also an unproven one.

Landmarks

A method that is prevalent in terms of navigation throughout the animal kingdom is the use of landmarks to remember the route. We as humans use landmarks all the time to navigate, and many animals do to. However, there is not known to be many bird species that use landmarks to navigate. In his experimenting with homing pigeons, Keeton (1979), found that the pigeons were being released so close to the home that they should have recognised the landmarks very easily. However, when they were released they still chose to rely on the sun and later the magnetic field rather than landmarks. This was proven when he equipped the pigeons with frosted contact lenses that only allowed two to three metres of visibility yet they still managed to navigate correctly.

It is interesting to wonder whether the pigeons would have resorted to using landmarks for navigation if all other methods were taken away from them, much like how on overcast days they were eventually trained to use the magnetic field for navigation. If all other methods were taken away from them, how would the pigeons navigate? Keeton did put bar magnets on the pigeons on cloudy days and noted that they did not navigate correctly, but I wonder if given time, would they adapt and begin to use other measures to navigate.