Description:
The ear tuft gene creates a group of feathers that stick out sideways from the chicken's head near the ear canal. It is not the same mutation that causes beards or muffs in Ameraucanas and a few other chicken breeds. It is lethal in homozygous form, and almost all embryos will die in the shell at about day 17. In heterozygous form, it still can lead to low hatch rates and trouble hatching.
Despite the high mortality rate, it is still common in some breeds of chicken, most notably the Araucana fowl, the Quetros, and other lesser known breeds.
Araucanas are the only breed recognized by the APA.
Tufted here refers to the "standard" het. tuft gene seen in birds. It is important to note that birds will still die in the shell in natural, het. tufted form.
Tufted x Tufted = 25% lethal gene (dead in shell), 50% tufted, 25% non-tufted
Tufted x Non-tufted = 50% Tufted, 50% non-tufted
Homozygous tufted hatching is incredibly rare and not likely to survive to sexual maturity, and thus not included here.
References & Further Reading
Somes, Ralph G. Jr., "International Registry of Poultry Genetic Stocks" (1988). Storrs Agricultural Experiment Station. 29. https://digitalcommons.lib.uconn.edu/saes/29
American Poultry Association. (2023). American Standard of Perfection (45th ed.).
RALPH G. SOMES, Ear-tufts: a skin structure mutation of the Araucana fowl, Journal of Heredity, Volume 69, Issue 2, March 1978, Pages 91–96, https://doi.org/10.1093/oxfordjournals.jhered.a108911]
Ralph G. Somes, Mary S. Pabilonia, Ear tuftedness: a lethal condition in the Araucana fowl, Journal of Heredity, Volume 72, Issue 2, March 1981, Pages 121–124, https://doi.org/10.1093/oxfordjournals.jhered.a109439
Noorai RE, Freese NH, Wright LM, Chapman SC, Clark LA (2012) Genome-Wide Association Mapping and Identification of Candidate Genes for the Rumpless and Ear-tufted Traits of the Araucana Chicken. PLoS ONE 7(7): e40974. https://doi.org/10.1371/journal.pone.0040974