the.com/cottontail

A rabbit's built-in surrender flag, flashed only after it's already too late to catch it.

means A wild rabbit of the Americas, named for the puffy white underside of its tail, which flashes into view as it bounds away.

from A straightforward 19th-century American compound — cotton plus tail — describing exactly what you see: a fluffy white tuft resembling a tuft of cotton. No hidden story here, just plain-spoken naming of the obvious feature, the same way 'bluebird' or 'redhead' got their names.

Genus
Sylvilagus, not the same genus as jackrabbits
The flash
White underside hidden until it flees, confusing predators
Nest style
Shallow fur-lined scrape, not a burrow
Peter Rabbit
Beatrix Potter's hero is literally named Cottontail's brother
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