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

Abstract

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.

The Oriental turtle dove (Streptopelia orientalis Latham, 1790) (Aves: Columbidae), a new species for the avifauna of Serbia

“…However, looking at the different photographs of this species on the Internet, we noticed that the somewhat longer bill tip is not unusual for this species. Although speculative in our case, it cannot be excluded that overgrowth of the premaxillary nail was caused by a nutrition deficiency, genetic mutations, collision traumas, diseases, or other known and well-described anomalies in wild birds (Pomeroy, 1962;Ledger, 1970;Purificação, 2019). Flying away due to human presence along with fine plumage conditions without clipped or damaged feathers represents reliable indicators of the wild origin of the bird.…”

Beak deformity in three bird species from the southwest of the Brazilian Amazon

“…Beak deformities in wild birds are relatively rare in nature, and cases are also rarely reported in the Brazilian scientific literature (Vasconcelos & Rodrigues 2006, Souza et al 2016, Purificação 2019, Smith et al 2019, Moura et al 2019, Moura et al 2020, Moura et al 2022, Moura et al 2023. These published records of beak deformities are timely and provide us with information that can tell us something about the health conditions of bird populations.…”

“…There are still occasional reports of beak anomalies in wild birds (Pomeroy 1962, Craves 1994, Handel et al 2010, Gorosito et al 2016, Smith et al 2019, Souza et al 2016, Purificação 2019, Smith et al 2019, Moura et al 2020, Moura et al 2022, Moura et al 2023). Knowledge about these cases will grow as researchers around the world begin to realize the importance of publicizing them.…”

“…Deformed beaks vary from small to extreme proportions (Gorosito et al 2016) and can assume different shapes, such as: crossed mandibles, decurved upper mandible, upcurved lower mandible, elongation of both mandibles, bent to the side and gapped (BTO 2024). Deformed beaks can affect the health of birds (Van Hemert et al 2012), but some individuals adapt to obtain food (Souza et al 2016, Purificação 2019. The alignment of the feathers with the use of the beak -i.e., preening, keeps the plumage in good condition and removes dirt particles and ectoparasites, such as feather lice and ticks (Scott 2010).…”

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“…However, looking at the different photographs of this species on the Internet, we noticed that the somewhat longer bill tip is not unusual for this species. Although speculative in our case, it cannot be excluded that overgrowth of the premaxillary nail was caused by a nutrition deficiency, genetic mutations, collision traumas, diseases, or other known and well-described anomalies in wild birds (Pomeroy, 1962;Ledger, 1970;Purificação, 2019). Flying away due to human presence along with fine plumage conditions without clipped or damaged feathers represents reliable indicators of the wild origin of the bird.…”