Isotopes are atoms that have the same number of protons and electrons but differ in their number of neutrons; they are lighter and heavier forms of the same element. Unlike radioactive isotopes, stable isotopes do not decay over time.
Black bears in Yosemite National Park that don’t seek out human foods subsist primarily on plants and nuts, according to a study conducted by biologists at UC San Diego who also found that ants and other sources of animal protein, such as mule deer, make up only a small fraction of the bears’ annual diet.
Their study, published in Methods in Ecology and Evolution, might surprise bear ecologists and conservationists who had long assumed that black bears in the Sierra Nevada rely on lots of protein from ants and other insects because their remains are frequently found in bear feces. Instead, the researchers believe that bears likely eat ants for nutrient balance. Continue reading →