Differential selection according to the degree of cheating in a status signal.

The maintenance of honesty in a badge-of-status system is not fully understood, despite numerous empirical and theoretical studies. Our experiment examined the relationship between a status signal and winter survival, and the long-term costs of cheating, by manipulating badge size in male house sparrows, Passer domesticus. The effect of badge-size manipulation on survival was complex owing to the significant interactions between the treatments and original (natural) badge size, and between the treatments and age classes (yearlings and older birds). Nevertheless, in the experimental (badge-enlargement) group, males with originally large badges had increased winter survival, while males with originally small badges had decreased survival. This indicates that differential selection can act on a trait according to the degree of cheating.