Mature saguaros begin as tiny black seeds that usually germinate under nurse plants, but only a few survive to adulthood. Young saguaros grow low to the ground, and those about the size of a thumb may already be several years old, while tall saguaros with many branching arms can be 175 or 200 years old. These “ancient giants” eventually die, decay, and leave woody internal skeletons on the ground. Saguaro reproduction begins in the hottest and driest weeks of late spring and early summer, when white-winged doves, bees, and bats visit blossoms and carry pollen. The fruit usually ripens in late June, and each fruit can contain as many as 2,000 seeds that feed coyotes, javelinas, foxes, rodents, and many birds along with the fruit’s red pulp. Seedlings are most vulnerable in their first years, when birds eat seeds and seedlings, people step on them, and intense sun or heavy rain can kill thousands of young plants. New saguaros survive best in the shade of nurse plants such as palo verdes and mesquites. They begin flowering after reaching about eight feet tall, may start growing arms at about 75 years of age, and in old age can weigh more than 7 tons and stand taller than a four-story building. Severe freezing, wind, lighting, vandalism, and disease can damage or kill them, and they seldom live more than 200 years.