We teach and talk about ecology as a tale of balance: the decline of one population generally leads to the increase in another. Nature abhors a vacuum. The cycling of predators and prey. Unfortunately, that complexity leads to a lot of problem in application. I can’t think of a better example than Macquarie Island, where cats were introduced about a century ago. The cats then destroyed the local community of birds. Unfortunately, when managers removed all the cats, the rabbits took over. There have been a bunch of similar stories on unanticipated ecological results and other catch-22s recently. Where I work, it’s not clear whether management should focus on the endangered San Joaquin kit fox or its prey, the endangered giant kangaroo rat. Managers in Washington are facing the same problem with orcas and Chinook salmon (you’ll recall that managers in Oregon had no such qualms about killing California sea lions that were eating salmon). Or take this study that shows prescribed burns in the Western U.S. could actually decrease our carbon footprint. Consider that swift populations in the UK are declining due to housing renovation projects.

There’s an emerging science on ecological traps, where changes in habitat (generally human-caused) lead to novel environments that appear to be high quality for a species, but are in fact low quality. In the Negev desert, for example, managers establishment of pits and dykes to increase moisture in certain areas led to increased mortality for an endemic lizard. The increased moisture led to trees, which served as perches for shrikes, who preyed on the lizards. The lizards had no exposures to trees and so didn’t anticipate the negative consequences.

In a recent discussion section for our wildlife ecology class, students were asked to draw parts of the Yellowstone ecosystem, to try to understand the consequences (direct and indirect) of removing wolves. After a sufficient number of convoluted arrows had been added among humans, wolves, elk, aspen, beaver, fish, soil, &c. &c., one student shouted “It’s all connected, man!” A total Berkeley moment.