A case of beak deformity in the Shiny Cowbird Molothrus bonariensis and a review on beak deformities in wild birds in Brazil

Beak deformities in wild birds are rarely reported. Here, I described a case of beak deformity in Shiny Cowbird, Molothrus bonariensis, and also provide a review on beak deformities recorded in wild birds in Brazil. In October 2016, I observed a M. bonariensis with a grossly elongated maxilla in the east region of the Mato Grosso state, Brazil. The literature review revealed 60 records of beak deformities in the Brazilian avifauna. The most common types of deformity were crossed maxillae or mandibles (38%), probable accidental injuries (27%), and elongations (15%). Deformities were reported in 35 bird species of 22 families. The most affected species was Ramphastos toco with 21 records. The number of published reports from Brazil was low overall, and are not related as an epizootic episode recorded in some bird communities.