"Aggressive" nesting magpies have attacked a group of power network maintenance workers in New Plymouth.
Lines company Vector has advised staff to wear hard hats to protect themselves from angry birds after attack in the Frankley Rd area last week.
"It was noted that the angry birds seemed to prefer harassing workers in the high visibility vests, rather than the more sedate blue drill pants and work shirts," the company said in its Network News.
Te Papa bird expert Colin Miskelly said magpies always dived from behind their target.
"They defend a territory centred on a nest, and some birds are more aggressive than others, you'll get some magpies that are quite laid back and some that are ridiculously aggressive and attack anything within 300 metres."
It was common to have magpies diving during this time of year, and Dr Miskelly said it could continue for up to three months.
The birds would not be specifically targeting the high visibility vests, he said.
"I'd say it's got far more to do with how close (the workers) are to the nest site."