Fig. 4. Allometric plot of chemoreceptor spike frequency adaptation vs body mass (Table 1). The heavy black regression line was calculated without phylogenetic correction (dotted line indicates 95% confidence interval); the heavy gray regression line was calculated with phylogenetic correction (see text). Regression parameters are summarized in Table 3. Values shown are all from this study: lovebird, quail, pigeon, Pekin duck and goose (see text). Silhouettes identify specific data points and are not scaled to actual bird size.