Trace Element Exposure and Accumulation

Photo Credit: Kent Keller

Golden Eagles are generalist predators but show a preference toward rabbits - both Jackrabbits and Cottontails. What happens when the rabbit population cycles to an historic low in as a diverse of a landscape like that of western Utah? Do the eagles then switch to other prey? What other prey? Are they moving up the trophic ladder with their selection? Will they be exposed to contaminants that could potentially biomagnify? Well, that’s what we’re trying to find out.

So far we’ve seen exactly that! Golden Eagles diversify their prey selection and it appears to largely be based on landscape variables. A significant confounder/opportunity arose during my study, though. Rabbit Hemorrhagic Disease 2 (RHD2) has an extremely high mortality rate among North American rabbits and is incredibly virile. It ‘showed up’ toward the end of my first field season and its impacts were felt substantially during my second field season. This has provided an opportunity to compare nest sites that focused largely on rabbits pre-RHD2 outbreak with sites that had to shift prey selection due to the decline in rabbits. We’ve seen differences in lead, mercury, and arsenic at a number of nests but analysis is still ongoing! More to come!