Outbreaks of avian influenza have led to the death or culling of millions of poultry and pigs and untold millions of dollars in losses to farmers and producers. Avian influenza is also a deadly disease that affects humans. A specific focus is on technologies that allow the identification of a pathogen before the outbreak of the disease. In the case of avian influenza, the stable isotope composition of a bird's feathers, claws or beaks reveals where the migrating bird began its journey; molecular techniques can detect the presence of viruses, such as avian influenza, in droppings of infected birds; and can pinpoint the species of birds that are infected. Combining the information gathered by these techniques, researchers can track birds as they travel, determine where they come from, what paths they have taken and which species are carrying the virus. This gives veterinary services a head start in predicting sites at higher risk of outbreaks.