SOUTH CHARLESTON, W.Va.  -- A migratory bird in the finch family is a cause for concern for backyard bird watchers in West Virginia.

Called pine siskins, the bird is flocking in large numbers in the state, meaning they could transmit salmonellosis to other species. The last time such an unusually large migration occurred, bird kills were reported throughout West Virginia from salmonellosis.

An unusually high migration of a species is called an "irruption."

The West Virginia Division of Natural Resources' wildlife section advises that backyard feeders be cleaned every two weeks and rinsed with a 10 percent bleach solution. The feeder should be thoroughly dried before refilling.

The cleaning is especially recommended for feeders containing thistle seed, a food favored by pine siskins