This project was based at Bangor University, UK, and funded by the Leverhulme Trust (Leverhulme Early Career Fellowship for 2017-2020 to Dmitry Kishkinev).

About 70 years ago, it was discovered that birds can use the Earth's magnetic field for finding directions (the magnetic compass sense). Since then, the magnetic compass has been demonstrated in many species, mainly by behavioural responses of birds (shift in oriented activity in round arenas) to a changed magnetic field. However, it is still poorly understood how exactly the magnetic sense is working and where magnetoreceptors reside in the bird's body. Recent studies have suggested that a bird's magnetic compass is a part of vision. Simplified, birds seem to 'see' magnetic field lines as visual patterns, perhaps superimposed on their normal visual perception of the world. Chemical reactions involving cryptochromes (CRYs) - a family of light-sensitive proteins - are assumed to play a crucial role in it.

It has been reported that the ability of birds to sense magnetic field depends on the presence of light with specific properties (e.g., only under specific wavelengths). To explain that, biophysicists proposed a Radical Pair Hypothesis (RPH). It suggests that CRYs form radicals (molecule with unpaired electrons) which are sensitive to the direction of ambient magnetic fields so that different alignment of radicals leads to different products in magnetoreceptors (supposedly, in photoreceptors where CRYs are found) depending on the direction of the magnetic field. Though the RPH is still hard to conceive, there is a growing body of experimental support for it. One line of evidence comes from studies reporting that electromagnetic (EM) noise (0-10 MHz) disturbs the magnetic compass sense in captive birds. Biophysics explains that by the resonance effect - specific radio frequencies may disturb unpaired electrons in the CRYs' radicals. Though RPH demands further investigations, the disturbing effect has been clearly shown by a few studies. Therefore, a question arises how human-induced and ubiquitous electromagnetic noise can affect birds' magnetic sense in the wild? To address it, the project aimed to conduct a set of experiments using homing pigeons. Trained pigeons return from tens of km and use both the sun (under clear sky) and magnetic (under total overcast) compass senses to keep directions. Pigeons were trained to home whilst carrying miniature GPS trackers and micro-generators attached to a bird as little 'backpack'. These devices are miniature enough to be carried by pigeons. GPS trackers document birds' trajectories whereas micro-generators act as a source of controlled and harmless broadband radio frequencies (RF) disturbances as well as slowly changing magnetic fields.

By processing tracking data, different parameters of homing performance were analysed (e.g., direction, speed, straightness etc.) and associated with the absence or presence of RF disturbances, weather conditions (cloudiness vs sunny sky) and some other relevant factors. The expectation was that if RF disturbances indeed affected birds' magnetic compass sense one should expect higher scatter of flight directions after release when the Earth's magnetic field is the main directional cue (e.g., in the absence of visibility of familiar landmarks and under total overcast when the sun is unavailable).