Weak or sick birds easy prey
Liz Taylor, of Christchurch, asked:
Where do birds go to die? We see lots of birds around, especially in the garden if you feed them in the winter, but rarely see dead ones.
Yolanda van Heezik, an ecologist at the University of Otago, responded:
When you see large flocks of apparently abundant birds, you may wonder why they become virtually invisible when they die. Most birds will end up in another animal’s stomach.
Unlike humans, birds generally do not die of old age. When birds are weak or sick they become easy prey for predators such as cats, rats and stoats, and are eaten right away. When they feel sick, birds will seek outoftheway places to hide, and predators may find them in these hideouts.
Those that die without being preyed on are often scavenged by predators. In cities in the United Kingdom, foxes are common scavengers of dead birds. Dead birds that are not found by mammals are quickly consumed by insects and other invertebrates, so the bird decays very quickly, depending on its size. Most birds have small light bodies that decompose rapidly.
Scavengers and decay make it difficult for wildlife biologists studying particular bird species to find carcasses in time to ascribe a cause of death. Even when tracking a bird using radio telemetry, which means its location can be determined when it dies and its body retrieved, unless it can be retrieved within a few hours of its death, it will most probably have disappeared, either dragged away by scavengers, or still be present but mostly eaten, and there’s not a lot that can be deduced from just a pair of legs.