aka Can US Wild Rabbits Breed with Domestic Rabbits
(c) Gryph- if you repost this article, please post with a link back to my website.
The short answer is: No, in the United States, wild rabbits (Sylvilagus spp. and Lepus spp. for example) cannot interbreed with domestic rabbits (Oryctolagus cuniculus).
Let's start with some background information. There are at least sixteen different breeds of rabbit native to the United States, including the cottontail rabbit. None of these breeds have ever been domesticated. Our domestic breeds, on the other hand, are derived from the European rabbit and are a distinctly different species from our native wild rabbits. This is not to say that domestic rabbits and wild rabbits won't attempt to mate- but if they do breed, embryos will die before birth due to the difference in chromosomes. Domestic (European) rabbits, for example, have 22 pairs of chromosomes, and cottontails have 21. My understanding is that in Europe, their wild rabbits can interbreed with domestic rabbits since they are the same species. But this article addresses the United States specifically.
There is a difference between feral rabbits and wild rabbits. Feral rabbits are domestic rabbits that have either escaped or been abandoned by their owners. Both domestic and wild rabbits can be the same color- the natural brown/gray agouti (typically called chestnut) color that is typical for a wild rabbit is also a common domestic rabbit color. Sometimes people think this means their domestic rabbit is, in fact, a cross between a cottontail and a domestic rabbit, but that is not the case as it is simply not possible.