White-headed marsh tyrant

The white-headed marsh tyrant (Arundinicola leucocephala), commonly referred to as the marsh tyrant, is a small passerine bird belonging to the tyrant flycatcher family. It is the sole species within the genus Arundinicola. This diurnal bird, exclusively found in South America, exhibits sexual dimorphism and is known to have monogamous mating behavior.

Male marsh tyrants possess a distinct appearance, featuring a white head with a small crest, a white throat, and a contrasting black body. They have dark brown irises, black legs, and a bill that consists of a black upper mandible and a yellow lower mandible. Typically, they weigh around 13 grams and measure approximately 13 centimeters in length.

Female marsh tyrants have a white forecrown and throat, along with a greyish-brown breast and flanks. Their wings and tail are also greyish-brown, although they are more uniform and significantly darker. The average weight of a female ranges from 12 to 12.5 grams, and she generally measures 13 centimeters in length. Females and juveniles have similar appearances.