A picky eater or someone who nibbles modest amounts of food at a meal is often said to "eat like a bird." In other words, the person doesn't eat much. Oh, how false! Birds actually consume a wide array of insects, nectar and other goodies, noshing frequently throughout the day. It may seem like they're not eating much because they eat a small amount at a time, but they are: Some insect-eating songbirds chow down every two seconds! A study by Smithsonian researchers showed that birds, along with lizards and bats, eat so many insects they indirectly benefit plants and help them grow [source: Smithsonian Tropical Research Institute].
The amount a bird eats depends on its size. Larger ones may eat a quarter of their body weight each day, while smaller ones up to half. And then there's the petite hummingbird, which famously consumes twice its weight every day in order to maintain its frenetic wing-flapping [source: Moss]. When it comes down to it, accusing someone of eating like a bird really means they're a bit of a pig. Assuming pigs really eat a lot!