"We see this crazy overlap of jays in campgrounds because of the density of food," Halbert told OurAmazingPlanet. The overpopulation also menaces federally protected species, such as snowy plovers, desert tortoises and California least terns - the jays eat their eggs too.
Steller's jays don't seek out murrelet eggs. But when the birds circle picnic areas near murrelet nests, some discover the chicken-size eggs make a fine treat. The smart, savvy birds will return to the same spot over and over, searching for food. Murrelets, to their misfortune, nest in the same tree every year.
Masters of disguise, the first marbled murrelet nest wasn't discovered by scientists until 1974, in Big Basin Redwoods State Park. The seabird doesn't actually build a nest, instead choosing a flat branch covered in cozy moss and needles, with cover to hide from airborne predators. At dawn and dusk, parents switch roles, flying offshore to dive for fish and invertebrates. [Watch the mysterious marbled murrelet]
"For an animal that lives for some 20 years, losing an egg is a terrible, terrible loss," Bensen said. "They're investing an enormous amount of energy into that one baby."