A specialised diet of nectar also means that hummingbirds have to produce a lot of urine (note that they also drink a lot of water). A lot. In fact, the urine they produce every day might amount to anywhere between 56 and 149% of body mass. For comparison, the urine normally produced by a human in a day amounts to somewhere between 1.5 and 2.5% of body mass. Note: Original photo cropped to reproduce best in square sizes.