Figure 2.

Preening selects for cryptically colored lice. Eight white (A) and eight black (B) rock pigeons were infested with live C. columbae that had been painted black or white to make them relatively conspicuous or cryptic, depending on background feather color (C, D). Each of the pigeons, which were isolated in 16 cages, received 30 conspicuous, and 30 cryptic lice, for a total of 960 painted lice across the 16 birds. Half of the white pigeons and half of the black pigeons, chosen at random, could preen normally (E), while the other half were fitted with “poultry bits” to impair preening ability (F, arrow). (G) Pigeons that could preen normally had significantly more cryptic than conspicuous lice at the end of the 48‐h experiment (Fisher's Exact test, P = 0.037). In contrast, there was no significant difference in the number of conspicuous and cryptic lice on pigeons with impaired preening (Fisher's Exact test, P = 1.0). Photos A&B by Sydney Stringham (reproduced with permission).