Photo by dcrafton; licensed under CC-BY-NC 4.0
Preventing a Pair of Parasites to Protect Golden Eagle Population
Conservation efforts can take many forms, from more abstract methods such as community outreach and habitat restoration to much more direct efforts. One of the most direct: keeping individual birds alive by treating disease. But can such focused methods have an effect on a species’ overall population?
A new paper, co-authored by our Executive Vice President of Science & Conservation, Dr. Chris McClure, and our Quantitative Ecologist Dr. Brian Rolek, aims to shed light on this question. Appearing in the Journal of Applied Ecology, the research focuses on the Golden Eagle and two particularly prevalent threats to their nestlings: poultry bugs (a biting insect parasite similar to bed bugs) and trichomonosis, a highly lethal disease of the digestive tract caused by a microscopic protozoan.
For two summers after the breeding seasons, the researchers treated nests (which are often reused from year-to-year) with one of several different experimental parasite treatments. Then, the following spring, the nestling eagles were examined to determine the effects of the treatment. Birds with active trichomonosis infections were directly treated with a dose of an oral antiprotozoal medication.
Of the nest treatments tested, one—a combination of powdered diatomaceous earth and a permethrin solution—resulted in significantly fewer poultry bugs when compared to nests that received other treatments. Nestling health was also significantly improved, with female nestlings growing to larger sizes and, on average, 0.7 more nestlings surviving to fledge. Meanwhile, ten nestlings from 27 nests that would likely have died from trichomonosis without treatment instead survived to fledge.
Extrapolating this information, the researchers estimate that treatment of trichomonosis in nestlings could increase eagle population growth rates by around 4%. Treating nests to prevent poultry bug infestation could have double the impact, increasing population growth by as much as 8%. Compounded over time, these cost-effective treatments could result in significant population increases, an intriguing possibility that could advise similar efforts for much rarer birds of prey.
