Do you really need to hold cockfights to be considered a felon? Apparently not. Merely breeding or owning pretty roosters will suffice. Witness this curiously nonspecific article trumpeting the takedown of a chicken breeding operation:
Montebello Cockfighting Raid
Now, whether these chickens were bred or used for fighting isn't the real issue. It's that no actual crimes were witnessed -- and since the "evidence of cockfighting" is unspecified, we don't really know what was found. But think on this:
Chickens that are not cage-confined FIGHT. It's just the nature of the species. Both hens and roosters will fight, often to the death, whether encouraged to do so or not. Even "placid" breeds will occasionally fight.
Now, consider a flock of free-range chickens intended for egg production. Chickens being chickens, there will occasionally be bloody fights, among both individuals and sometimes as "gang warfare" among rival social units. (And no way to predict when this will happen. The only way to prevent it is by individually caging each chicken.)
Now, imagine if an HSUS representative were to witness and document those chickens fighting, as chickens will do when let "act naturally". Under a hostile reading of the law, could an egg producer then expect to get raided for "cockfighting"??