With fewer than 400 birds remaining in the wild, the Dominican Republic's Ridgway's hawk is one of the most critically endangered raptors in the world. Numbers are steadily decreasing due to a botfly infestation, seriously reducing the number of fledglings each year. Researchers received a Morris Animal Foundation grant to study the problem, and the group devised a highly successful short-term solution by treating nests with a common flea and tick insecticide. The team found treating the nests and nestlings several times during breeding season significantly increased the fledglings' chance of survival; for every 10 nests treated, researchers saved eight nestlings that would otherwise die from parasitism. Although successful, the treatment method was labor-intensive, requiring tree climbers to treat and monitor nests three to five times during the breeding season. In this newly funded study, researchers will test a longer-acting insecticide that only requires a single nest application prior to egg laying. This new strategy, if successful, could be a more practical method for treating not only the nests of Ridgway's hawks, but also other endangered island-endemic bird species affected by botfly infestations.
Grant amount awarded
The Peregrine Fund
David L. Anderson, PhD
"Native Parasitic Nest Fly Impacts Reproductive Success of an Island‐Endemic Host," Animal Conservation, September 2018
"More than just Nestlings: Incidence of Subcutaneous Philornis (Diptera: Muscidae) Nest Flies in Adult Birds," Parasitology Research, June 2020
"Is the Grass Always Greener on the Other Side? Weak Relationships Between Vegetation Cover and Parasitic Fly Infestations," Parasitology Research, September 2021