1. Armitage KB (1998) Reproductive strategies of yellow-bellied marmots: energy conservation and differences between the sexes. J Mammal 79:385–393
2. Barash DP (1977) Sociobiology and behavior. Elsevier, Amsterdam, 378 pp
3. Bertram CRB (1978) Living in groups. In: Krebs JR, Davies NB (eds) Behavioural ecology: an evolutionary approach. Sinauer Associates, Inc, Sunderland, MA, pp 64–96
4. Brown JL (1973) The evolution of behavior. W.W. Norton & Company, Inc, New York, 76 pp
5. Crook JH, Ellis JE, Goss-Custard JD (1976) Mammalian social systems: structure and function. Anim Behav 24:261–274