Lesson's motmot (Momotus lessonii) or the blue-diademed motmot, is a colorful near-passerine bird found in forests and woodlands of southern Mexico to western Panama. This species and the blue-capped motmot, whooping motmot, Trinidad motmot, Amazonian motmot, and Andean motmot were all considered conspecific.
The central crown is black and surrounded by a blue band. There is a black eyemask. The call is a low owl-like ooo-doot.
These birds often sit still, and in their dense forest habitat can be difficult to see, despite their size. They eat small prey such as insects and lizards, and will also regularly take fruit.
Like most of the Coraciiformes, motmots nest in tunnels in banks, laying about three or four white eggs.
The Lesson's motmot has three subspecies: