![prey densities vs predators prey densities vs predators](https://i1.rgstatic.net/publication/273765537_Invasive_Toads_Shift_Predator-prey_Densities_in_Animal_Communities_by_Removing_Top_Predators/links/59d94bc0a6fdcc2aad0d9078/largepreview.png)
In their study, the researchers looked at the feeding behaviors of three co-occurring species in the Bering Sea, all of which consume juvenile pollock or krill – black-legged kittiwakes, thick-billed murres and northern fur seals. Credit: Photo courtesy Kelly Benoit-Bird, Oregon State University These juvenile pollock are critical prey for many species in the Bering Sea. "What we discovered is that smaller aggregations of prey are more attractive to predators if they are sufficiently dense." "Predator populations that should have been doing well, based on prey numbers or biomass, were in fact not doing well," added Benoit-Bird, an associate professor in OSU's College of Earth, Ocean, and Atmospheric Sciences. But the results didn't match what we might have expected. "When we first tried to identify good foraging locations for predator species we looked at areas of high prey numbers because it makes sense that they'd be where the food is. "We had to think very differently about these interactions, trying to see the world from the predators' point of view," said Kelly Benoit-Bird, an Oregon State University marine ecologist and lead author on the study. The study was part of the Bering Sea Integrated Ecosystem Research Project, which was funded by the North Pacific Research Board and the National Science Foundation. Results of the study were published this week in the journal PLOS ONE. When prey doesn't aggregate, however, the search for food becomes much more difficult – affecting the health of the predators' offspring and the vitality of their overall population. Predators need to balance how much energy they expend in searching for food with the caloric and nutrient value of that which they consume. It's more than searching for an easy meal, the researchers say.