THE EFFECTS OF CROSS-FOSTERING ON ASSORTATIVE MATING BETWEEN ZEBRA FINCH SUBSPECIES

Zebra finch subspecies, Taeniopygia guttata guttata and T. g. castanotis, were cross-fostered to members of the other subspecies and their subsequent mating preferences measured. In multiple matechoice tests, an individual could show a preference for perching near a particular bird but physical contact was not possible: in one-way mate-choice tests, stimulus birds were prevented from seeing the individual being tested by one-way mirrors; in two-way mate-choice tests, wire-mesh screens allowed visual interaction between the test individual and the stimulus birds. In subsequent pair-formation tests, the same birds could form pairs freely in an aviary. When both sexes were cross-fostered, the birds preferred members of the foster subspecies in mate-choice tests and formed mixed pairs in the aviary. However, when only one sex was cross-fostered and the other was raised normally by members of their own subspecies all the cross-fostered males, and the majority of cross-fostered females, paired with members of their own subspecies in the aviary, irrespective of their preferences in one-way mate-choice tests. Birds spent more time with the individual they later mated with in the aviary in two-way than in one-way matechoice tests in all studies. In mate-choice tests, when both sexes were cross-fostered significantly more females than males chose their future mate. However, when only one sex was cross-fostered more normally raised than cross-fostered birds chose their future mate, irrespective of sex: this suggests that rearing experience has an important influence on which member of the pair ultimately chooses the mate. © 1990 The Association for the Study of Animal Behaviour.