Araucana chickens

The araucana chicken has no tail that is not only no tail feathers but has no tail. They lay blue eggs.

When the Araucana was first introduced to breeders worldwide, in the mid-20th century, it was

quickly realized that the genetics that produced tufts also caused chick mortality. As it turns out, two copies of the gene causes nearly 100% mortality shortly before hatching. One copy causes about 20% mortality. The tufted gene is dominant however. Because no living araucana possesses two copies of the tufted gene, breeding any two tufted birds leads to half of the resulting brood being tufted with one copy of the gene, a quarter being clean faced with no copy of the gene, and a quarter of the brood dead in the shell having received two copies of the gene.
In the decades to follow, most breeders took one of two tactics - either to preserve the old style of bird, or to breed out the tufts while increasing productivity.
In 1976, the first standards for the breed were accepted by the APA, conforming to the traditional style. This was followed, in 1984, by a second standard for the "improved" variety.
The gene for blue eggs is dominant, so the term "Easter Egger" is used to describe birds of mixed breeding that produce such eggs. Unfortunately, these mixed breeds are often incorrectly labeled as Araucanas or Ameraucanas, and marketed to backyard poultry hobbyists who are not aware of the difference