Screaming as a strategy to reduce the predation risk incurred by begging?

Following the theory of parent-offspring conflict parents request from thei r offspring an honest signal of food requirement to optimally adjust feedin g rate. For this purpose, offspring display a highly informative signalling system, begging vocalisation, for which the conspicuousness to predators m aintains honesty, since only hungry offspring are willing to take this risk . The risk of predation incurred by begging activities challenges our under standing of how begging vocalisation could evolve towards a high degree of noisiness. A solution to this apparent paradox resides in the possibility t hat alongside the evolution of begging, birds also evolved strategies that reduce the risk of being depreciated, Following the ornithological literatu re nestlings scream in the presence of a predator to frighten it, induce pa rents to rescue them and siblings to flee from the nest and hide in the veg etation. I therefore propose the hypothesis that nestling screaming behavio ur evolved as a means of reducing the risk of predation incurred by conspic uous begging. Comparative analyses supported the prediction postulating tha t species in which nestlings scream in the presence of a predator produce b egging calls that are more conspicuous to predators than calls of non-screa ming species. This suggests that the predation cost of begging lies not onl y in terms of predation per se but also in the requirement of anti-predator strategies.