1. Birkhead, T. R. & Møller, A. P. Sperm Competition in Birds: Evolutionary Causes and Consequences (Academic, London, 1992).
2. Wong, Z., Wilson, V., Patel, I., Povey, S. & Jeffreys, A. J. Ann. hum. Genet. 51, 269–288 (1987).
3. Bruford, M. W., Hanotte, O., Brookfield, J. F. Y. & Burke, T. in Molecular Genetic Analysis of Populations: A Practical Approach (ed. Hoelzel, A. R.) 225–269 (IRL, Oxford, 1992).
4. Kempenaers, B. et al. Nature 357, 494–496 (1992).
5. Smith, S. M. Behaviour 107, 15–23 (1988).