young, but the monotremes lay eggs . live birth also occurs in some non-mammalian species, such as guppies and hammerhead sharks; thus, it is not a distinguishing characteristic of mammals. mammals have three bones in each ear and one (the dentary) on each side of the lower jaw; all other vertebrates...
in summer provide food for thousands of migrating birds (whitney ). but the tundra is a fragile environment where anthropogenic changes can pose risks, such as found from pollution from mining and oil drilling activities, erosion, pesticides to control insects, and construction activities. as stewards...
have also led beetles, moths and butterflies to emerge earlier than in recent years. similarly, hibernating species like frogs and bears emerge from hibernation earlier in warm springs. all species don't respond to warming the same way. when species that depend on one another—such as pollinating insects...