In the Middle Ages in Europe, massive plague epidemics killed millions of people. Plague has not been eliminated. It can still be found in Africa, Asia, and South America. Today, plague is rare in the United States. But it has been known to occur in parts of California, Arizona, Colorado, and New Mexico. The three most common forms of plague are: Bubonic plague, an infection of the lymph nodes.
Dear Herb, Lucky bunnies to have landed in your yard! :). Cottontail rabbits start to wander from their nest at the age of about 2-3 weeks, but will stay in the yard for longer, depending on how hospitable the environment is. If you don't see them in the nest, don't assume that you still couln't hit one with the mower as it hides in the grass, hoping to stay out of sight.
If you find a wild baby rabbit, let him be, and do not attempt to rescue him. Mother cottontails feed their babies only once or twice a day, and then stay as far away from the nest as possible, so as to avoid attracting predators.