[Read the Article]
New Caledonian crows are renowned for their ability to craft, modify, and use tools [see previous video]. Now, Rutz et al. provide an explanation for this remarkable ability -- by comparing the stable-isotope profiles of crows’ tissues with those of their food sources, they found that tool use materially enhances the crows' diet and, therefore, may improve their evolutionary fitness. In this narrated video, author Christian Rutz explains how the crows extract these larvae from their wooden burrows, making repetitive, “teasing” movements with a stick tool until the larvae open their mandibles in defense and latch onto the tip of the tool, allowing the crow to lever the larvae out.