abstract: In a recent interspecific comparative study of birds, Møller & Birkhead (1993) used two com-parative techniques, the comparison of indepen-dent linear contrasts (Harvey & Pagel 1991) and pair-wise comparisons of sister taxa (Møller & Birkhead 1992), to show that male parental care (feeding of chicks) is significantly negatively related to extra-pair paternity. The pair-wise com-parisons were included to show that the main result was independent of statistical technique (Møller & Birkhead 1993), and to control many confounding variables (Møller & Birkhead 1992). These comparisons appeared strongly to support their argument because 10 of 11 pairs varied in the predicted direction (sign test: P=0·012). There are at least four major problems with Møller & Birkhead’s (1993) pair-wise compari-sons. In going through these below, I shall show that further testing of Møller & Birkhead’s (1993) hypothesized relationship between extra-pair paternity and paternal care is necessary and that pair-wise comparisons can often be an inadequate test for behavioural questions. I have re-analysed the corrected data, and the revised pair-wise comparisons no longer support the hypothesis that male parental care covaries with extra-pair paternity (sign test: P=0·55).