Fig. 9. Comparison of (A) glomerular filtration rate (GFR) and (B) effective renal plasma flow (ERPF) of birds in relation to habitat type (TA, terrestrial arid; TM, terrestrial mesic; FW, freshwater; MR, marine). Data are calculated from residuals of logGFR or logERPF on log(body mass) (Fig. 8; raw data and sources are given in Table 1) and are expressed as mean residual values ±S.E.M.