PS 45-1
Court cleaning behavior by the lekking bird White-bearded Manakin and a test of the anti-predation hypothesis
Forest lekking birds such as manakins, cock-of-the-rocks, peacock pheasants, and birds of paradise may clean debris and pluck leaves from their displaying courts on or near the forest floor. Functions of court cleaning include optimization of light incidence on courts to improve male plumage contrast against background during displays (scientific proven hypothesis), and an anti-predation strategy facilitating the detection of ground-based predators, such as lizards and snakes (unproven hypothesis). Here, we experimentally test the anti-predation hypothesis using a pit viper replica in (simulating a non-camouflaged predator) and surrounding (camouflaged predator) courts of the White-bearded Manakin Manacus manacus, a small lekking passerine inhabitant of lowland forests in South America. We perform 10-min experimental trials with 21 different males in southeastern Brazil. The snake replica was first placed on the leaf litter 10-20 cm from the court and then after 20-50 min it was placed in the court’s central cleared area. If males reacted (with small escape flights and alarm calls) to the snake replica, we assumed that they detected it likely identifying it as a potential predator. The frequency of alarm calls and the initial time until reaction (latency) for each male were compared.
Results/Conclusions
Seventeen out of 21 males detected the snake replica in the area with leaf litter adjacent to courts, whereas all the males promptly detected the replica in the central cleared area of courts, rendering no significant difference in detection probability. The frequency of alarm calls by males when the replica was placed in the leaf litter or in the court cleared area also did not differ statistically. However, there was a higher latency in the reaction of males for the emission of the first calls and short escape flights when the snake replica was placed adjacent to courts compared to immediate reactions of males when the replica was in the court suggesting that the cleared area of the court contributed to make terrestrial predators such as snakes more conspicuous to males. In this sense, what matters to a successful predation upon M. manacus (and probably other forest lekking species) are the predator’s position and camouflage amidst leaf litter together with its ability to develop a rapid strike to ensure a kill before being detected. Our results support the anti-predation hypothesis.