How can we record reliable information on animal colouration in the wild?

Animal colouration is a phenotypic trait that can provide important information on species ecology and adaptation. Describing animal colours can be very challenging, and digital images may help in this difficult task. Obtaining an image with colours similar to those observed in nature is not trivial, as many factors can alter the final result. Some studies highlighted the importance of a proper post-production and analysis of the images to obtain the best results, but unfortunately very little attention has been paid to how to obtain standardised images suitable to be employed in zoological and ecological studies. This study aims to give evidence about the importance of shooting pictures in standardised condition to obtain reliable data on animal colourations. We provide a method that allows to obtain standardised pictures with colours that are comparable to those observed on wild animals. We used a method that creates an in situ standardised environment to shoot photos of relatively small animals. Our method allows to fully control lights, the factor that affect pictures the most. We also provided a test on the efficiency of this method. Using a colour checker card as reference, we compared the divergence of the Red-Green-Blue channel values obtained from pictures shot in complete darkness with those read by a colorimeter. The average divergence in RGB values between the colorimeter and the RAW images was about 4%. This divergence increased when light disturbance occurred. Our method highlighted the importance of the moment in which pictures are taken, and demonstrated that a fully controlled method is essential for obtaining reliable information on animal colourations, data that can be employed in ecological and evolutionary studies.