Surprisingly, MMR did not differ between experimentally infected and control birds at any phase of the experiment (t = −0.20; figure 2), nor did it differ between free-living birds with zero, low or high parasitaemia at any period (p > 0.47; figure 3; electronic supplementary material, table S2). However, MMR changed greatly over the study period in both captive and wild birds. In experimental birds, MMR increased by about 50% from pre-inoculation to early post-inoculation phases and remained high until the end of the experiment (figure 2). Although these rises in MMR paralleled increases in body mass in captive birds (figure 2), MMR increased relatively more than mass and much of this mass-increase was associated with fat accumulation (electronic supplementary material, figure S1), which has negligible metabolic activity.