For the past 15 years, wild birds have died in Alabama at surprisingly regular three-year intervals during winter months due to paralysis induced by feeding ticks. If the pattern continues, there is reason to expect that Alabama residents may see a number of wild birds killed again by ticks this winter. While feeding on a bird host, the adult female tick introduces a chemical substance in her saliva that induces a progressive, ascending paralysis of the muscles that can ultimately kill the bird if the tick is not removed.
Paralysis begins in the feet and legs, progressing upward to affect the wings and thoracic muscles.
Death is usually attributed to respiratory failure following paralysis of the diaphragm muscles. Hemorrhaging of the lungs and gastrointestinal tract are contributing factors. If the ticks are removed before the paralysis progresses too far, birds generally recover, often with dramatic results, within a few hours. Affected birds become lethargic, often exhibiting lameness and a staggering gait. As the paralysis progresses, they are unable to perch, have difficulty flying, and are seen crouching or lying on the ground.