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A, nting is stereotyped behavior in which birds expose themselves to fluid-secreting ants or other pungent substances. During "active" anting a bird crushes an ant in the bill and rubs it frenetically through its plumage (Rothschild and Clay 1952). During "passive" anting a bird entices ants to crawl through its plumage by crouching or lying on an ant hill with spread wings and tail. Although anting has been recorded for more than 200 avian species, most of them passerines, its adaptive significance remains controversial (Ehrlich et al. 1986, Simmons 1986, Potter 1989). Univ. Press, Oxford. NERO, R. W., AND D. R. M. HATCH. 1984. Common Grackles anting with marigold flowers. Blue Jay 42:212-214. POTTER, E. F. 1989. Response to P. R. Ehrlich, D. S. Dobkin and D. Wheye. Auk 106:163-164. ROTHSCHILD, M., AND T. CLAY. 1952. Fleas, flukes and cuckoos. Collins, London. SIMMONS, K. E.L. 1966. Anting and the problem of self-stimulation. J. Zool. (Lond.) 149:145-162. SIMMONS, K. E.L. 1986. The sunning behaviour of birds. Bristol Ornithol. Club, Bristol, United Kingdom. WHITAKER, L. M. 1957.

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Relatively little u known about the mating behaviour of hermaphrodite freshwater snails, many of which transmit the Schistosoma trematodes among humans in developing countries. Knowledge of the breeding biology of these snails could help in the design of schistosome control programmes, as well as possibly contributing to our understanding of the evolution of simultaneous hermaphroditism in animaLv Here we describe an experiment investigating the patterns of sexual roles adopted by the Schistosoma mansoni-veclot snail, Bwmphalana glabrata. During observations on groups of freely interacting snails, no individuals copulated significantly more often in the male than in the female role, or vice versa. Only one individual showed a pattern of alternating sexual roles over successive matings that differed significantly from a random sequence of roles. There was no evidence for reciprocal copulation with one particular partner, either between consecutive matings (unless they were temporarily isolated from other snails) or between non-consecutive matings (separated by copulations with other conspecifics). We discuss these results in the context of sex allocation and ESS mating strategy theories.

Inbreeding depression has been studied extensively in m any anim als, but the potential of 'social facilitation' (a response to the presence of conspecifics in the environm ent) to influence reproduction has received little attention. Studies of reproductive o u tp u t in freshw ater herm aphrodite snails have im plicated inbreeding depression, but never social facilitation, in the reduced reproductive o utput of isolated com pared with p aired /g ro u p ed snails. In this experim ent, isolated, self-fertilizing Biomphalaria glabrata snails had reduced reproductive o u tp u t com pared with paired, predom inantly cross-fertilizing snails. However, the reproductive outp u t of control snails (paired, but prevented from cross-fertilizing) was sim ilar to th at of paired, cross-fertilizing snails, suggesting th at the low reproductive outp u t of snails in isolation was not simply due to inbreeding depression with self-fertilization. I suggest th at an absence of social facilitation, caused by deprivation of social com m unication as a result of isolation, m ay play a role in reducing reproductive o utput of isolated B. glabrata, and th at future studies of inbreeding depression using isolated and p aired /g ro u p ed herm aphrodite snails should be designed to control for possible effects of social facilitation.