A bird's beak contains a vascular layer of blood vessels and

A bird's beak contains a vascular layer of blood vessels and nerves located between the outer keratin shell and the inner bone. A main, sensitive blood vessel, often called the "quick," runs down the center, which can bleed profusely if injured or cut during grooming. 

Key Details About Bird Beak Blood Vessels:

• Structure: The beak consists of a bony framework covered by a thin layer of skin (dermis), and a hard outer layer of keratin (rhamphotheca). The blood vessels and nerves are situated within this vascular layer, which provides sensation.
• Sensitivity: The tip of the beak, particularly in parrots, contains many nerves and blood vessels, making it sensitive to heat, pressure, and pain.
• Injury Risk: Because of this blood supply, if a beak is trimmed too far or broken, it can bleed heavily and cause pain.
• Overgrown Beaks: When a bird's beak becomes excessively long, the blood vessel (quick) can extend further down, requiring gradual trimming over months by a veterinarian to allow it to recede safely.
• Bruising: A bird's beak can become bruised, which appears as discoloration, similar to a human bruise. 

If a bird's beak is bleeding, it should be treated immediately by a professional, as improper care can result in severe blood loss.