Artificial colour mutation: do red-painted great tits experience increased or decreased predation?

Abstract

A brightly coloured mutant may suffer increased predation (by being conspicuous) or may be favoured by reduced predation (if predators avoid novel or rare varieties). These alternatives were examined in a 2-year study of great tits,Parus majorby painting and ringing 1655 fledglings near 27 pairs of nesting sparrowhawks,Accipiter nisusA minority (<10%) of the great tits in each hawk territory were manipulated. On average, 40.7%of the fledglings in each brood were bright red, the others controls (yellow). Based on ring recoveries at hawk nests, the percentage of red tits taken was 5.5%, compared with 4.0% for controls, indicating an increase in predation rate by 38% for red birds. The results were similar in both years. However, using hawk pairs as sample units, predation risk was not significantly higher for red tits. Hawks that caught only one painted tit did not take red ones more often than expected, whereas those that caught two or more tits tended to take red ones more often. A predation cost for bright mutants may initially be low or absent, later increasing with the frequency of the mutant. In addition, tit parents fed red fledglings more often than controls, indicating a possible parental preference for red.