Pigeon and loft
15/10/2005 - Bacteria are single-cell creatures that are invisible to the naked eye. Their size varies from 0.1 to 10 microns (1 millimetre = 1,000 microns). Their structure varies from the simple to the complicated – for example, some do not even have a cell wall. For our purposes, we distinguish beneficial and pathogenic bacteria, though this classification is arbitrary and not necessarily precise. For example, some types of bacteria are largely beneficial or neutral for pigeons, but in certain conditions can still become pathogens.