Removal behavior of botfly larvae live subcutaneously from their own and brood-parasitic nestlings.

URSINO, CYNTHIA A; DE MÁRSICO, MARÍA C; REBOREDA, JUAN C

Cape May (NJ)

Congreso; Joint Meeting of Association of Field Ornithologists (AFO) and Wilson Ornithological Society (WOS); 2019

Cape May Bird Observatory

Brood parasitic birds lay their eggs into the nests of other birds, abandoningparental care of their nestlings to the unsuspecting hosts. Parasite and host nestlings may themselves be parasitized by botfly larvae (Philornis: Muscidae). Infection by botfly larvae causes nestling mortality in many Neotropical birds. Despite the lethal effects, most Philornis hosts studied so far lack specific defenses against these larvae. Here, we provide the first direct evidencethat adult baywings (Agelaioides badius), the primary host of the specialist brood-parasitic screaming cowbird (Molothrus rufoaxillaris), regularly remove botfly larvae from their own and parasitic nestlings by pulling them out of the nestlings? skin. All nestlings in the brood were preened exhaustively throughout the day and the larvae were removal at a very early developmental stage. By combining nestling cross-fostering with video recording of baywing nests, we show that due to prompt removal, infection with botfly larvae had negligible effects on nestling growth and survival despite high prevalence. This is theonly bird species known to remove botfly larvae which burrow under the nestlings? skin. Our results provide the first direct observations for larvae removal behavior in botfly hosts. Screaming cowbirds may benefit from using baywings as its main host, as larvae removal by adult baywings reduces the costs of botfly parasitism.