Pipraeidea bonariensis acepta huevos parásitos de Molothrus bonariensis pero no cría con éxito a sus pichones

SEGURA LUCIANO; GONZALEZ EXEQUIEL; MONGES VIRGINIA; CHIRAMBERRO ANA PAULA; GERSTMAYER PAULA; JAUREGUI ADRIÁN

Gramado

Congreso; II Congreso de Ornitología de las Américas; 2023

Brood parasites reduce host breeding success and favor the evolution of antiparasitic defenses, suchas the parasitic egg/nestling recognition and rejection. Molothrus bonariensis is a Neotropicalgeneralist brood parasite and Pipraeidea bonariensis has been listed as its host. We monitored 82host nests (2013-2019) in central-east Argentina and found that 35% were parasitized. Parasiticeggs were accepted in 92% of the nests and hatched in 78.5% of the nests that completed theincubation stage (alone in 18% of the nests, with a single host sibling in 27%, and with two hostsiblings in 55%). No parasitic nestling survived (92% due to apparent starvation between the secondand sixth day of age and 8% due to predation). When the parasitic nestling shared the nest with ahost sibling, we only observed the death of the parasitic nestling. In parallel, we videotaped 11 nonparasitized and seven parasitized nests during the nestling stage and observed that hosts deliveredexclusively fruits (never insects). Although the ability to recognize and discriminate has beensuggested as an effective antiparasitic defense mechanism, our results indicate that the null nestlingparasite success was more linked to the type of food delivered than a potential parasitic nestlingrecognition. Our finding also highlights on the controversial strategies of parasitism of M.bonariensis in terms of host selection, since although our host did not successfully rear any parasiticnestling, the occurrence of parasitism was high, suggesting that there would be little or no hostselection by the parasite.