Figure 1.
Courtship feeding of cedar waxwing modelled by biological auctions. (a) Male cedar waxwing provides a berry to the female during courting. Courtship feeding is common in many species [15,16]. Photo taken by Minette Layne (CC). (b) Three males are courting for two females. Green male offers a nuptial gift of value 0.7, orange male of 0.9 and brown male of 0.3. The left female (v1 = 1) picks the orange male and the right female (v2 = 0.6) picks the green male. Such a scenario can be modelled by biological auctions with multiple rewards. The pay-offs of the males are the rewards won minus their investments (here the value of the female minus the value of the nuptial gift). The green male obtains a negative pay-off of −0.1, the orange male obtains a pay-off of 0.1, and the brown male ends up without a reward and a pay-off of −0.3.