Here's a true case of angry birds, but it's not funny. A hidden camera is revealing the vicious evolutionary survival skill of killer honeyguide chicks. African honeyguide moms lay their eggs in other birds' nest, and soon after their chicks hatch, they hack their foster siblings to death. The disturbing video shows a much larger honeyguide nestling, still birth blind and featherless, peck to death a tiny bee-eater hatchling. It's the first time such an attack by the chicks with the needle-sharp beaks has been filmed.
"While the apparent violence with which young honeyguides attacked their newly hatched foster siblings was quite shocking at first sight, it shows the power of evolution to shape amazing adaptations in parasites," the lead researcher tells the BBC. In another canny move, the honeyguide mother "ensures her chick hatches first by internally incubating the egg for an extra day before laying it, so it has a head start in development compared to the host," and can easily attack its foster siblings, he explains. The honeyguide chick is then the only one left in the nest to be fed and cared for by its victims' mom. (Read more honeyguide chicks stories.)