Every now and then as I'm jogging at dawn I round a corner, surprise a rabbit in the road, and he takes off running hard away from me. Just a glance at the critter is enough to convince me that he's not a cottontail. He's a lot larger, his much longer ears stand straight up as he runs, and his manner of running is also different -- less "hoppy" and more flat-footed-racy. He's a Blacktail Jackrabbit, what old timers sometimes call Jackass Rabbit, LEPUS CALIFORNICUS. You can see a Blacktail Jackrabbit at www.nps.gov/tont/nature/jackrabbit.htm
An Eastern Cottontail's head and body are 14-17 inches long while a Blacktail Jackrabbit's is 17-21. Cottontails weigh 2-4 pounds and jackrabbits 3-7. A cottontail's ears are 2«-3 inches long while a jackrabbit's are 6-7. When cottontails are spooked they tend to hide in nearby thickets or burrows, but jackrabbits hightail it overland. An escaping jackrabbit leaps two or three yards at a bound, touching the ground only with his toes.
Eastern Cottontails don't occur this far west but in the foothill valley bottoms we do have Mountain Cottontails, which look a lot like their Eastern cousins. We also have Whitetail Jackrabbits, even larger than Blacktails, found higher in elevation than here.
With all the lush nibblings available nowadays I think our jackrabbits must be thinking they have it made. However, soon the dry season will hit and the herbaceous layer will dry up fast. Then we'll see if the garden fence does its job keeping jackrabbits at bay.