Figure 4.

Change in beak coloration from pre- to post-KLH adult challenge for B2, S1R, S1U, and H4b grouped by young treatment (KLH or no KLH). Beaks of males exposed to KLH as nestlings (n = 9) were less red than the beaks of males not exposed to KLH as nestlings (n = 34) both prior to, and following, adult challenge with KLH. Males from both treatments became duller on average from pre- to postchallenge, and the magnitude of change was similar between the treatments. Dark arrows indicate the direction in which values correspond to redder beaks; for example, smaller values for brightness are associated with redder, more carotenoid-rich beaks, whereas higher values for saturation at high wavelengths are associated with redder beaks. Bars represent mean ± SE for the young treatments.