Habitat and Life Cycle
The only animal known to counteract the poison of the cockatrice was the cockerel. 
Cockatrice versus Basilisk
Originally, cockatrice was synonymous with the word basilisk; however, in the fourteenth century, Chaucer wrote of a fantastic animal he called the Basilicok.  This eventually transformed into the better-known cockatrice.
Considered to be a relative to the Basilisk, the cockatrice is a separate species. 
Cockatrice Most Poisonous
The cockatrice is so venomous that anyone who attempted to spear it could die, for the cockatrice could cause its own poison to travel up the length of the spear.  It could kill any living thing with a mere glance,  or in some instances, a cockatrice's glance turns living things to stone. 
So noxious is the poison of the cockatrice that it could rot fruit off trees from a distance.  A cockatrice could pollute the waters from which it drank, and the water would remain poisonous for centuries. 
The depiction of the cockatrice on the shield of a medieval knight would be considered quite fearsome. 
During the Tudor Period (late fifteenth to early seventeenth century AD), the legend of the cockatrice's deadly poison was such that it became a namesake: first, to an enormous brass cannon; then to a venomous Armenia lizard. 
The cockatrice has several descriptions. It has been described as a monster with the wings of a fowl, tail of a dragon, and the head of a rooster.  Some cockatrices have a second head at the ends of their tails. [2,3]
Alternatively, the cockatrice is described as a winged reptile with the legs and crest of a rooster.  Or, the cockatrice is a serpent with the head, neck, and legs of a cockerel, the face of a human, yellow body and wings of a dragon. 
A Legend of the Cockatrice
Once, England became infested with cockatrices. There seemed little hope until a knight dressed himself in mirrors. He walked throughout the countryside attired those mirrors, and all the cockatrices saw the reflections from their own eyes and perished. 
For more information on footnotes and references, please see the bibliography.