Rohwer, S. 1977. Some experiments in deception. The evolution of reliable and unreliable badges of fighting ability. The cost of dominance and the advantage of subordination in a badge signaling system. Delayed maturation in passerine plumages and the deceptive acquisition of resources.
Distress screams as a measure of kinship in birds.
Burley, N. 1979. The evolution of concealed ovulation. The evolution of sexual indistinguishability. Chiron Press, N.Y. Whoriskey, F.G. 1991. Stephens, M.L. 1984.