CONICET | Buscador de Institutos y Recursos Humanos

Myiasis,the infestation of living tissue by fly larvae, has been confirmed to causedeath in nestling birds and may be a driving force to the extinction of somebird species. However, bird-parasite interactions are historically understudiedand we are lacking key information on the effect of myiasis on bird productivityand implications for population-level declines and extinctions. Because reasonsfor the decline of many island endemic bird species in the Neotropics areincompletely known, improving our understanding of host-parasite relationshipsmay be critical to restoring threatened and endangered species. The Ridgway?sHawk (Buteo ridgwayi) is a critically endangered small forestButeo endemic to Hispaniola. Fieldobservations have revealed mortality of Ridgway?s Hawk nestlings due to heavyinfestations of the Dipteran parasite Philornispici. Our objective was to determine the impacts of Philornis parasitismon nestling survival and hawk productivity. During the spring breeding seasonof 2015, we studied 50 nesting pairs of Ridgway?s Hawk in Los Haitises NationalPark in the Dominican Republic. We visited control (n=23) and treatment (n=27)nests weekly, recording nestling morphometrics and prevalence of parasitic flylarvae. At each visit of treatment nests we applied a 0.29% fipronil solution inthe nest and on nestlings at a rate of 14mg/kg topically to prevent botflyinfestation. Treatment resulted in a significant decrease in median number ofparasites from 18 maggots/nestling to 0, and a significant increase in numberof young fledged per pair from 0.43 to 1.19, a 173% difference in productivitybetween groups. Our findings confirm a significant, negative impact of Philornis parasitism on the Ridgway?sHawk population that is likely a major contributor to the decline of thespecies.