Breed Recognition in the Social Interactions of Domestic Fowl1)

The hypothesis that in social interactions between breeds of chickens, behavioral responses are based on breed recognition rather than on individual recognition factors was tested by: (a) paired contests between birds having previous experience with the other breed, (b) formation of small multibreed flocks, and (c) morphological modification of dominant birds of another breed or of strangers belonging to the breed winning paired inter-breed contests. Inter-breed contests pairing winners in previous contests between the breeds typically led to fighting while pairing losers typically resulted in mutual avoidance to a far greater extent than did similar pairings within a breed. The social hierarchy developed in 13 of 15 small (less than ten individuals) multibreed flocks was one of complete dominance of one breed over the other. This tendency also existed, but in lesser-degree, in more complex (number of pair relations) flocks of about fifteen birds. Strangers of a dominant breed were accepted as dominant individuals without challenge by individuals of the subordinate breed. Morphological modifications (coloring, dubbing) of the dominant breed penmates did not modify recognition by the subordinate breed birds even though similar modifications led to loss of individual recognition within a breed. Modification of strangers of a breed previously winning paired inter-breed contests led to slight loss of breed recognition on the part of defeated birds of another breed. Behavioral responses based on breed recognition without discrimination of individuals established a situation in which a single brief experience with one member of another breed had a profound influence upon subsequent reactions to other individuals of that breed encountered within the memory span. In small flocks this led to a tendency for members of one breed to react to the other breed as an entity. Strange individuals placed in flocks of another breed were accepted as dominant birds without challenge if members of their breed had previously defeated or dominated members of the flock.