Eric Walker added The limits of egg recognition: testing acceptance thresholds of American robins in response to decreasingly egg-shaped objects in the nest to American robin

Eric Walker added How an Eight-Sided ‘Egg’ Ended Up in a Robin’s Nest - The New York Times to American robin

Eric Walker added American robin - Wikipedia to American robin

Eric Walker added a number of links to American robin, and added American robin to Turdus

Eric Walker added American robin to Turdus, and added Turdus to Turdidae