Woodpeckers mixing: 
Don't many species of ducks cross-breed? This article states that Mallards have been known to mix with 50 other species and Wood Ducks with 25.
http://www.ducks.org/conservation/waterfowl-biology/waterfowl-hybrids
Don't warbler species cross-breed?
My friend in California/SF Bay area has posted photos of red-shafted and yellow-shafted flicker hybrids. 
RBWO and Flickers are about the same size. And, they are both woodpeckers. 
(It would be a lot crazier if the flickers and gnatcatchers were pairing up.)

______________________________________________________________________

Ohio-birds mailing list, a service of the Ohio Ornithological Society.
Please consider joining our Society, at www.ohiobirds.org/site/membership.php.
Our thanks to Miami University for hosting this mailing list.


You can join or leave the list, or change your options, at:
listserv.miamioh.edu/scripts/wa.exe?LIST=OHIO-BIRDS
Send questions or comments about the list to: [log in to unmask]