The versatility of Coq de Leon or Gallos de Leon feathers is much under utilized by fly tyers outside of Spain, often being regarded as just a tailing material. In fact in Spain there is a whole genre of flies tied with these feathers known as Pardón de Meana. You can find a step by step instruction to tie the following fly and lots of information about Pardón de Meana at http://www.pardondemeana.com/paso_a_paso_libro.aspx
The website also offers flies for sale and has a book about their history and more step by step tying illustrations.
To demonstrate the numerous possible uses of these feathers, my friend Jonathan Hoyle experimented with the different types of fly he could tie using Gallos de Leon and produced all the following flies from a single Mazo:
Sedge tied on Hends BL 454 #16, body tan dubbing, head brown dubbing, antennae Gallos de Leon fibres curled with nail. Tied by Jonathan Hoyle