STRAIGHT-LINE MOVEMENT AND COMPETITIVE MATE SEARCHING IN PRAIRIE-RATTLESNAKES, CROTALUS-VIRIDIS-VIRIDIS

Males compete in various ways for mating and reproductive success. Phy logenetic factors and local ecology affect female spatial and temporal distributions, which in turn influence the form of male competition, sexual selection and mating systems. In prairie rattlesnake, Crotalus viridis viridis, populations where (1) males seek females during a bri ef reproductive period, (2) females are relatively few, and (3) female s are widely and unpredictably distributed spatially into small discre te clusters, males should show efficient mate searching more so than t ime-consuming 'handling' (e.g. fighting, mate persuasion). Natural his tory studies and computer and mathematical modelling generate this exp ectation. This long-term field study of prairie rattlesnakes in Wyomin g indicated that straight-line (i.e. fixed-bearing) movement by males is critical for mate location and, thus, for mating success. Males tha t searched along straight-line paths located and mated with more femal es than those having less straight movement paths. Fighting was observ ed rarely, and no relationship was found between males' success at mat e location and body mass and/or snout-vent length. Thus a range of tra its may mediate competition and mating success among male snakes. (C) 1997 The Association for the Study of Animal Behaviour.