Get your binoculars and field guide and head to a local park, as it's National Go Birding Day! Held on the last Saturday in April, this holiday celebrates birdwatching, an activity enjoyed by millions worldwide. There are approximately 18,000 known bird species around the world. Birds come in a wide range of sizes, colors, and behaviors, making them one of the most diverse groups of animals on Earth—from imposing eagles to today's tiny snowy-winged star, a leucistic Anna's hummingbird in the Australian Garden at the UC Santa Cruz Arboretum. These hummingbirds are typically vibrant in color, but leucism means some have decreased pigmentation, resulting in a paler appearance. Unlike albino birds, these hummingbirds do not have red or pink eyes. Their lighter plumage reduces protective camouflage, making them more vulnerable to predators such as hawks and feral cats.