Red-winged Blackbird with Avian Keratin Disorder

Avian Keratin Disorder: Understanding Beak Abnormalities in Birds

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While photographing a Red-winged Blackbird, I noticed its lower beak was longer than the upper one. This deformity is often linked to Avian Keratin Disorder (AKD), a condition that affects birds’ beaks, causing excessive growth, curvature, or misshapen structures.

Red-winged Blackbird with Avian Keratin Disorder
A Red-winged Blackbird perches on a dried plant stem, displaying an overgrown lower beak, a sign of Avian Keratin Disorder (AKD).

What Is Avian Keratin Disorder?

AKD occurs when the keratin layer of a bird’s beak grows abnormally, leading to overgrowth or misalignment. Normally, keratin growth in birds is regulated through natural wear and tear, feeding behavior, and regular preening, which help maintain a functional beak shape and length. The disorder can affect one or both mandibles, making feeding, preening, or defending difficult. Researchers believe AKD may result from environmental contaminants, nutritional deficiencies, disease, or genetic mutations.

Most Affected Species

AKD is frequently observed in chickadees, woodpeckers, jays, nuthatches, and raptors, but other species, including blackbirds and waterfowl, can also be affected. In Alaska, a high number of Black-capped Chickadees with AKD have raised concerns about environmental factors.

Red-winged Blackbird with Beak Deformity Due to Avian Keratin Disorder
This Red-winged Blackbird’s abnormal beak growth, seen from a different angle, highlights the effects of AKD, which can impact feeding and preening.

Symptoms and Effects

  • Overgrown beak – Either the upper or lower mandible becomes excessively long.
  • Curved or crossed beak – Misalignment can hinder food grasping.
  • Cracks or irregular texture – Affected beaks may appear brittle or rough.
  • Feeding difficulties – Birds may struggle to consume food efficiently.
  • Poor feather condition – Inability to preen properly can lead to feather deterioration.

Possible Causes

  • Environmental contaminants – Pesticides, heavy metals, or industrial pollutants may disrupt keratin development.
  • Nutritional deficiencies – Lack of essential vitamins like Vitamin D or biotin may contribute to deformities.
  • Diseases and viruses – Some studies suggest viral infections, such as poikilocytosis virus, could be linked.
  • Genetic mutations – Some cases may have hereditary origins.

How to Help

  • Monitoring and Reporting – Reporting cases of AKD to research organizations helps track patterns.
  • Reducing Chemical Exposure – Limiting pesticide and industrial pollution may decrease risks.
  • Providing Supplemental Food – Birds with beak deformities may struggle to eat, so backyard feeders can offer support.

If you spot a bird with beak abnormalities, consider reporting it to organizations like the U.S. Geological Survey (USGS) or the Cornell Lab of Ornithology. You can report observations to the USGS at their Beak Deformity and Banded Bird Observation Report or submit data to the Cornell Lab’s FeederWatch Project. Their data collection efforts help researchers better understand this disorder.

This Red-winged Blackbird’s beak abnormality highlights how wildlife health can reflect larger environmental changes, such as habitat destruction, pollution, and climate shifts that impact food availability and ecosystem balance. Have you ever encountered a bird with a beak deformity? Share your observations in the comments.

📷 Photo Details
Camera: Canon EOS R5 Mark 2
Lens: Canon RF200-800mm F6.3-9 IS USM
Location: Sequoyah National Wildlife Refuge, Oklahoma

2 thoughts on “Avian Keratin Disorder: Understanding Beak Abnormalities in Birds”

  1. Thank you so much for sharing this information! I’ve been seeing some type of sparrow or finch at our feeder with a long, curved beak and wondered what was going on with it. I will report it via the links you provided. This post was so helpful!

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