Despite their aggressive reputation, loud screams and fierce, piercing looks, the red-tailed hawks at the park north of Burlington, just west of the Colorado-Kansas border, were being bullied when Gaines saw them.

"I've never seen red-tails harassed so much. They all seemed hoarse. I felt kind of sorry for them," said Gaines of the sight of dozens of little birds dive-bombing the hawks.

The hawks were minding their own business, Gaines recalled.

But the western kingbirds at the park were upset.

Highly territorial, the kingbirds felt the hawks were intruding on their space, said Gaines, a Westminster scientist who helps develop vaccines and tests used in veterinary medicine.

Gaines had focused his camera on one red-tailed hawk because the bird had been screaming. As he followed the hawk across the sky, a kingbird dive-bombed the hawk.

The hawk, which is not a predator of the kingbird, flew as fast as it could from the kingbird. For a moment it appeared the kingbird had stopped attacking. But then it began the pursuit again and — to Gaines amazement — landed on the hapless red-tail's back.

"He rode the hawk for 25 yards. The hawk was not trying to fight back — it was just trying to get out of there," said Gaines.

As the kingbird rode bareback on the hawk, it pecked away at the hawk's head.

"They (the kingbirds) are not afraid of anything," said Gaines. "Until this happened, I had never seen one perch on a hawk's back."