Corvidae

Lore & Background

Corvids are found worldwide except for the southern tip of South America and the polar ice caps. Most species are in tropical South and Central America and southern Asia, with fewer than ten species each in Africa and Australasia. The genus Corvus re-entered Australia in relatively recent geological prehistory, with five species and one subspecies there. Several raven species have reached oceanic islands, some now threatened or extinct. Over time, evolutionary relationships have been debated; current research treats corvids as the core group of the Corvoidea, with closest relatives including birds of paradise, Australian mud-nesters, and shrikes. The jays and magpies do not form monophyletic lineages but split into American and Old World, and Holarctic and Oriental lineages, respectively. The crested jayshrike and Hume's ground jay are not true corvids.

Reader's Guide

Corvids are significant for their high intelligence relative to body size, demonstrated through self-awareness in mirror tests (Eurasian magpies) and tool-making (crows and rooks). Their brain-to-body mass ratio equals that of non-human great apes and cetaceans, only slightly lower than humans. Ecologically, they are omnivorous and adaptable, with some species thriving in human-altered environments. Studies show that increased crow and magpie numbers due to human development do not necessarily cause higher nest predation of smaller birds compared to other factors like habitat destruction. Corvids exhibit complex social behaviors, including hierarchical organization, mutual aid, and elaborate play. Their fossil record extends to the mid-Miocene, about 17 million years ago, with early genera such as Miocorvus and Miopica. The family's evolutionary origins are from Australasian ancestors, spreading worldwide from there. Their legacy includes being among the most intelligent birds studied, challenging previous assumptions about cognitive abilities in non-mammals.

Did You Know?

• The raven is the largest passerine bird.
• Eurasian magpies have demonstrated self-awareness in mirror tests.
• Corvids have a brain-to-body mass ratio equal to that of non-human great apes and cetaceans.
• The earliest corvid fossils date to mid-Miocene Europe, about 17 million years ago.