Artificial selection in show-type budgerigars (Melopsittacus undulates) has led to heavier and larger birds compared to wild-type budgerigars. In particular, breeders who exhibit their budgerigars at shows want large birds with long feathers on the head, partially covering the eyes, and large black dots on the throat feathers. In this study, we wanted to know whether (reproductive) behavior differed between morphological types of budgerigars, and if so whether it influenced their fertility. 24 pairs of budgerigars in breeding boxes were videotaped about three weeks before egg-laying, and the tapes were analysed using The Observer Video-Pro.

Males paired to females that later laid eggs flew from perch to perch significantly more often than males whose females did not go on to lay eggs. The frequency of flying in males was negatively correlated with the desired characters: the heavier the male, and the larger the throat dots, the lower the frequency of flying. Males with large throat dots showed more courtship behavioral acts than males with smaller throat dots. The number of courtship behavioral acts was positively correlated with the fertility rate of the future eggs. There were no correlations between the courtship of the male and morphological traits of the female, or morphological differences within the pair.

This study is an example of integrating morphological traits and the measurement of behavior to address the question of how morphology - and especially artificial selection of morphological traits in companion animals - might affect their reproduction.

Paper presented at Measuring Behavior 2002 , 4^th International Conference on Methods and Techniques in Behavioral Research, 27-30 August 2002, Amsterdam, The Netherlands

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