All right, it's true that many people - perhaps most people - wouldn't call a healthy jackrabbit population a blessing. Here in the Southwest, jackrabbits are largely taken for granted; like ravens, we see them around a lot but don't really notice them much. Hardly anyone remarks, "Hey, I saw a jackrabbit today!"
When jackrabbits do get noticed, the reference is usually negative. They get into your garden and eat the crop. They girdle your fruit trees. They compete with livestock out on the range (it is said that seven jackrabbits will eat as much forage as a sheep).
Or one leads your bird dog off on a merry and futile chase when the dog was supposed to be hunting quail.
First of all, despite the name, jackrabbits aren't rabbits at all, they're hares. The gestation period of a rabbit is about 30 days. Hares hold their young seven to ten days longer. And where rabbit young are born bald, blind, and helpless, a just-born hare is already in fur, with eyes open, and the little leveret can hop around. Rabbits, such as the cottontail, like cover; they live in burrows or brush piles and when pursued hard they look for cover or a hole to provide an escape. Hares spend their entire lives on top of the ground, hooding up in a "form" - a mere depression in the grass - when they're not out feeding or moving about. Flushed by a coyote, fox, greyhound, or eagle, a hare will attempt to outrun rather than hide from a predator.
By any or all of the above determinants, the jackrabbit is a hare. The most sensible explanation I've heard for the name "jackrabbit" is this one: the striking long ears of this hare caused the descriptive moniker, "jack-ass rabbit," later shortened to jackrabbit.
As Aesop knew when he matched a tortoise against a hare, you can't talk about hares without talking about speed. The hare the greyhound chases at the race track is artificial, but the one out in the field is real. By knowing something of greyhound speed one can infer the speed of a jackrabbit.
Greyhounds have been clocked at an attained speed of 50 mph coming down the first straightaway. Take such hounds to the open field, flush a jackrabbit, and what happens?
Usually, the hound is able to overtake the hare one or more times, forcing the jack to change direction in order to escape, indicating the superior speed of the hound. More often than not, in the ensuing high-speed chase, the jack is able to elude the hounds with a myriad of high-speed moves until the hounds begin to tighten up (usually inside of a mile). At that point the hare is once more able to straighten out into a sprint, stringing the pack out and leaving them behind.
At times, however, one encounters some remarkable jackrabbits. I have seen both blacktail and whitetail jacks start up not ten yards in front of greyhounds of proven speed - fresh, healthy hounds on good running ground - and literally run away from them. These hares beat greyhounds at a straightaway sprint!
I have been running jackrabbits with greyhounds, salukis, and other sight hound breeds for 30 years. It is clear that the best jackrabbits are capable of an attained speed of at least 40 mph, and of maintaining that speed for a mile or more. That a hare is capable of outrunning a specially bred dog like the greyhound, a quadruped six to ten times its size, is surely one of the most remarkable feats in the realm of natural history."