THE INFLUENCE OF HABITAT AND MALE MORPHOLOGY ON A MATE-CHOICE CUE - THE DISPLAY NESTS OF WRENS

Wrens, Troglodytes troglodytes, are highly polygynous passerines. Male s build cock nests that are displayed to females and function as a mat e-choice cue. Males with large numbers of nests are more likely to att ract females than males with fewer nests. To be useful to females a cu e used in mate choice must contain information. One way to evaluate th e information content of such a cue may be to examine the factors that influence its size. The number of nests was Predicted on territories with known building rates (immigration) and nest destruction rates (de ath) using an immigration-death function. This analysis suggested that if only building rate and destruction rates were considered then the number of nests on territories was consistently overestimated. In 1994 an experiment was conducted in which nest-site availability was manip ulated. Males provided with additional nest sites built more nests and continued to build later in the year resulting in longer nest-buildin g periods than controls. The converse was found when nest sites were e xperimentally removed. This suggested that the number of nests that co uld be constructed on a territory was limited by habitat structure. No ne of the morphological characters considered here significantly influ enced the number of nests built by males. Therefore, the information c ontent of this mate-choice cue will be primarily about characteristics of the habitat on the territory rather than characteristics of the ma le. (C) 1997 The Association for the Study of Animal Behaviour.