Fig. 2. Effect of nutritional stress on the (A) brightness and (B) size of melanin-based ornamental plumage in male house sparrows. Nutritionally stressed males (dark bars) were deprived of food for randomly assigned 6h periods on 3 out of every 4 days (sensu Hill, 2000), while unstressed males (white bars) were allowed access ad libitum to the same type and amount of food. Badge size and brightness were measured with Adobe® Photoshop® from digital photographs. Values are means + 1 S.E.M. For badge brightness, more negative values indicate blacker plumage.