How much birds eat greatly depends on the species. For instance, chickadees can eat around 30 to 35 percent of their body weight on a daily basis.
Some birds eat smaller amounts, and one example is the raven. This species of bird typically eats less than 5 percent of its body weight on a daily basis. Hummingbirds, on the other hand, eat nearly 100 percent of their body weight in the form of nectar and insects. One major factor in how much birds eat is the nutritional value of food. Birds that eat more insects commonly eat less per day. Other things that factor into how much a bird eats are temperature, body size and the bird's activity level.