Mother robins may start incubating their eggs during the evening after the second egg is laid, or after all the eggs are laid. They sit on the eggs for 12 to 14 days. The female usually does all the incubating. Even in good weather, she rarely leaves her eggs for more than 5 to 10 minutes at a time.
By 95-100 years in age, a saguaro cactus can reach a height of 15-16 feet, and could start to produce its first arm. By 200 years old, the saguaro cactus has reached its full height, reaching upwards of 45 feet tall. Some saguaros have been seen with dozens of arms, while other cactus never produce a single one.