Tuesday, June 12, 2018

American Rabbits Are Not Walt Disney Rabbits

Baby Eastern cottontail rabbits in a typical scrape nest. 

Proof that most Americans spend far too little time in field and forest is the startling level of ignorance about American rabbits and hares. It seems most people know more about the rabbits of Watership Down and Warner Bros. cartoons ("Shhhhh, we're waa-bit hunting!") than they do the living, breathing bunnies that live in the parks and pastures within walking distance of their homes.

First the simple fact: No North American rabbit or hare dens underground. Though there are a lot of rabbit species in North America, all are "cottontails" -- various species and subspecies of the Sylvilagus genus.

No species of Cottontail Rabbit digs earth dens like its European counterpart, nor do North American rabbits or hares have their young underground. The North American rabbit (Sylvilagus genus) is not closely related to its European counterpart (Oryctolagus genus) -- they split from each other hundreds of thousands of years ago.

This is not to say a rabbit will not tuck itself under an old truck, under a pallet of wood near a barn, or between hay bales, especially in the presence of dogs or humans. They will also dive into a groundhog hole to avoid a dog or to get out of the weather if a really strong storm sweeps in, but they do not dig the holes, nor do they enter them very deeply, nor do they stay in the mouth of a hole for very long.

While European rabbits make permanent communal burrows, North American rabbits make solitary (and well-concealed) "scrapes" on the surface of the soil. These scrapes (sometimes called "forms") are 6 or 7 inches long, about 5 inches wide, and about four inches deep. They are often shielded from view by tall grass and weeds. The mother rabbit will pull her own belly fur out in order to line the scrape and further hide the young (see picture, above). The mother rabbits will generally avoid the scrape during daylight hours when she might be seen, returning only under cover of darkness to feed her young. The baby rabbits, which are born without fur and with shut eyes, will be covered with fur and have open eyes in about 2 weeks, when they will begin to leave the nest and eat vegetation on their own.

The nesting density of cottontails is habitat-specific. In an unkempt orchard with thick grass you might find one rabbit next every 2 acres, while densities are likely to be about one nest per 7 acres in a rich hayfield, and 13 to 14 acres per nest in woodlands and dry rocky pasture.

A home range of three or four acres is very common for cottontails which, if chased, will stay within their home ranges rather than bolt cross country.

North America has hares too -- most of them we call "jack rabbits." Jack Rabbits and Snowshoe Hares are larger than most cottontails, have much larger ears, and are also faster. Unlike baby rabbits, which spend two or three weeks helpless in their nests, hares are born fully furred, eyes open, and ready to run "right out of the box". Hares build no nests of any sort.

Rabbits and Hares are "lagomorphs" -- a kind of primitive placental mammal dating back to the Paleocene times, about 62 million years ago in Asia. Along with rabbits and hares, this Order also includes the Pikas we find in the western US.

Lagomorphs practice "coprophagy" -- i.e. they eat their own feces. "First pass", rabbit pellets are greenish in color and are collected right from the animal's own anus. These rabbit pellets are then re-chewed in order to absorb all the nutrients in hard-to-digest plant material, much as a cow chews its cud.

By engaging in coprophagy, rabbits and hares are able to spend relatively little time exposed to predators in the field while feeding.

European rabbit warren near Susex, England.  The only American native rabbit that dens underground is the pygmy rabbit (about 1 pound in weight) which is extinct in its native Columbian Basin, with one species still extent in southern Idaho. 


Steff said...

Thats a fantastic photo of a rabbit warren would you mind if I used it in a powerpoint for teaching a class of animal care students?

PBurns said...

Go ahead -- not my photo, but fair use doctrine always prevails. Just be sure to note that U.S rabbits do not den underground. :)


Lauren said...

I'd always assumed that feral introduced rabbits were common in the US. From time to time I have seen stories about breeding populations that were founded from released pet rabbits.

PBurns said...

Feral European rabbits generally die of disease and predation before establishing. You might get a released pet bunny living for a few months, but rabbit calcivirus, coyotes, fox, hawk, dogs and poor habitat seem to trim them out of the wild in pretty short order. I know of no state that has a European wild rabbit population to speak of.