KNOXVILLE, Tenn. (AP) _ A burgeoning population of buzzards has caused at least 16 power outages in the Tennessee Valley Authority utility system because of a pileup of bird droppings on cable insulators, a TVA spokesman says.

''They roost on our big transmission towers that hold the power lines, and their droppings keep hitting the insulators,'' TVA spokesman Bill Steverson said Wednesday.

''They're causing us a heck of a lot of headaches,'' he added.

The federal utility's minor problem with the ungainly birds is turning into a bigger one, as a mild winter apparently coaxed the migratory buzzards to stay a while longer in Tennessee and Alabama, where most of the power failures have occurred, Steverson said.

Last year, there were only two outages attributed to the birds, he said.

''They usually fly through here in the spring on their way south, but since we've had such a mild winter, our folks are speculating that they just stopped here and didn't bother going any further,'' Steverson said.