What Are the Causes of Stress Bars in Feathers?

One of a bird's most important features is its feathers. Whether they are bright like a parrot's or dull for camouflage like a sparrow's, feathers give birds the gift of flight. When a bird is unhealthy or having problems getting an adequate diet, this can show up in in the form of discolorations, known as stress bars, on a bird's feathers.

  1. Background

    • Feathers are constantly replaced throughout a bird's life.

      Bird feathers are complex structures that only last about a year before they are replaced. Each feather grows from a follicle that starts out encased in a sheath. In the beginning, the feather shaft is dark as blood travels through it to provide nutrients to the feather. If the feather is broken while it is still growing, it will bleed profusely. Once the feather is fully grown, the bloody supply closes off and the feather is "dead," like people's hair.

    Signs

    • Stress bars are depigmented or black lines perpendicular to the shaft of the feather. Multiple lines may show up and down the feather. Feathers with several stress bars may be weak and fall out easily. The occasional stress bar on a feather is not reason for concern. However, if multiple stress bars appear on feathers all over the bird's body, this is an indication there may be a health problem, especially if there are other symptoms, such as dry, flaky skin and rough, ungroomed feathers.

    Causes

    • Growing feathers require several nutrients, and stress bars are an indication of an interruption in these nutrients getting to the newly formed feathers. It's not uncommon for fledglings to have these discolorations on their first feathers from stressors, such as improper temperature or a missed meal. However, in mature birds, stress bars can be a sign that they are not receiving the correct diet that should include plenty of vitamin A, which is important for maintaining skin and feather health.

    Prevention

    • A veterinarian can help a bird owner figure out what diet is best for preventing feather problems, such as stress bars.

      Once a feather develops stress bars, there is no way to reverse the effect. The feather eventually falls out and is replaced by another. Stress bars can be prevented through feeding a proper diet and keeping an eye on a bird's overall health. For parrots, a formulated pellet diet should be 65 percent to 80 percent of their feed, vegetables should be 15 percent to 30 percent and the rest can be treats, such as nuts and fruits. Other types of birds commonly kept as pets, such as finches and lorikeets, have different nutritional requirements, so it is important to consult an avian veterinarian to formulate their diet.