The large and brilliantly-colored monarch butterfly is among the most easily recognizable butterfly species that call North America home. Monarch butterflies are found across North America wherever their habitat’s needs are being met. They are broken into two populations separated by the Rocky Mountains, called the eastern and western populations.

Monarchs lay their eggs on milkweed. As caterpillars, monarchs feed exclusively on the leaves of milkweed, wildflowers in the genus Asclepias. North America has several dozen native milkweed species with which monarchs coevolved and upon which they rely to complete their life cycle.

The monarch migration is one of the greatest phenomena in the natural world. Monarchs know the correct direction to migrate even though the individuals that migrate have never made the journey before. They follow an internal “compass” that points them in the right direction each spring and fall. A single monarch can travel hundreds or even thousands of miles.

Most of the world’s bats eat insects, and in areas with cold winters, that is all they eat. Many tropical bats eat fruit and nectar, and a few are carnivores that eat other animals, including rats and mice, small birds, frogs, lizards, or even fish. Only three out of more than 1,000 species drink blood.

Most experienced bat scientists can guess what a bat eats by looking closely at its adaptations. Each species of bat is adapted for the food it eats. Some bats specialize in eating just one or a few kinds of food, but others are generalists who eat various foods. Special adaptations, such as wings, feet, eyes, nose structure, and mouth structure, allow bats to find and eat certain kinds of food with little or no competition from other species. This is very successful as long as their unique food source is abundant, but such specialization is risky because the kinds of prey, fruit, flowers a bat eats might die out, leaving the bat to starve. Animals that eat various foods can switch types if one disappears, but they cannot compete well with specialized animals for any one food.

North America is home to an incredibly diverse range of birds, from the majestic national icon—the bald eagle—to the remarkably resilient whooping crane. More than 800 bird species occur in the United States. Some live here year-round, others migrate here seasonally, and some stop in on their migratory routes to other countries. Of these birds, dozens are listed on the U.S. endangered species list, facing threats such as climate change, habitat loss, pollution, and invasive species.

Perhaps the easiest way to identify a bird is feathers—but they share several other characteristics. Birds are vertebrates, meaning they have backbones. All female birds lay eggs, which the young develop before hatching. These animals are warm-blooded and can regulate their body temperature. All birds have wings, but not all birds use them to fly. Penguins and ostriches, for example, do not fly.