Rook

Corvus frugilegus

Nests in raucous colonies in tall trees and solves puzzles in lab tests. Group-chat courier.

Population: ~38,000,000–71,000,000 mature individuals globally (decreasing trend)
Habitat: Open agricultural land, pasture and arable fields with tall trees nearby for breeding, plus wooded steppe, riverine plains and urban peripheries/parks; avoids dense forest, wetlands, and heavily built-up urban cores; most rookeries below ~120 m elevation, though the species' broader habitat suitability extends up to 2,000 m
Fun fact: Captive rooks have solved Aesop's-fable-style water-displacement puzzles (dropping stones into a tube to raise the water level and reach a floating food reward), demonstrating tool-use and physical-causal reasoning on par with some great apes despite never using tools in the wild.
Range: Palearctic — from Scandinavia and western Europe across Russia to central/eastern Siberia (extent of occurrence ~37.6 million km² breeding, ~35.4 million km² non-breeding); western populations (C. f. frugilegus) largely resident, eastern populations (C. f. pastinator) and northern/eastern populations partially to fully migratory
Diet: Omnivorous, roughly 60% plant matter (cereal grain, potatoes, roots, fruit, acorns, berries, seeds) and 40% animal matter, mainly earthworms and insect larvae probed from soil with its bill, plus beetles, spiders, millipedes, slugs, snails, and occasionally small mammals and birds
Size: 0.45 m
Wingspan: 0.9 m
Lifespan: 23 years

More Clever Corvids