In Texas, Pennsylvania, and elsewhere, people have reported seeing Northern Cardinals that are red on one side and brown on the other, indicating that a bird is half male and half female. This anomaly occurs in other species of birds, as well, not just cardinals. Insects, too! Scientists…

Feathers are amazing structures. But after about a year, constant use and exposure to the elements mean they have to be replaced. So how do you replace the roughly 20 feathers in each wing that are essential to flight? Many species — such as this Common Raven — molt just a few feathers at…

This American Kestrel evolved to nest in tree cavities or small caves in cliffs. We humans have made life difficult for kestrels. Development has shrunk the open spaces they need. We’ve cleared away dead trees they rely on for nests and sprayed pesticides that eliminate the insects the…

A movie runs at 24 frames per second, just right for humans to sense as normal speed. Pigeons process the visual world several times faster. The frantic car chase that puts us at the edge of our seats would likely appear—to a pigeon—more like a slideshow or PowerPoint. A bird’s rapid-fire…

Many woodpeckers chisel out deep cavities in tree trunks in order to lay their eggs and raise their brood. The cavities hollowed out by the birds vary in size, depending on the species of woodpecker. The chamber of a tiny Downy Woodpecker descends about a foot from the opening, while the…

The spider’s web is an intricate piece of precision engineering. Made from large proteins, it’s sticky, stretchy, and tough. So it’s no surprise that many small birds — including this Anna’s Hummingbird — make a point of collecting strands of spider silk to use in nest construction. Spider…

Male Great Egrets have special long feather plumes called aigrettes, which they use in courtship displays in the spring. These beautiful big birds were nearly hunted to extinction for these special feathers, which were used to adorn ladies’ hats. The plight of the egret spurred people to…

Con su excelente sentido del olfato, los cerdos son famosos por su capacidad para descubrir trufas, un hongo que crece debajo de la tierra y que es muy preciado por su sabor. Pero resulta que algunas especies de aves también pueden encontrar su camino hacia un premio trufado…

As singers go, American Robins are exceptional. They’re often the first birds to sing in the morning, and the last you’ll hear in the evening. While their average song strings fewer than a dozen short phrases together and lasts only a few seconds, robins sometimes sing for minutes without…

Evolution on islands can produce unusually large species. Haast’s Eagle lived on the islands now known as New Zealand. With a wingspan of 9 feet and weighing up to 30 pounds, the eagle hunted the moa — a flightless bird that stood over ten feet tall. The eagles probably vanished not long…