NIIGATA -- Aggressiveness is all you need to triumph in unrequited love.

You You, a male crested ibis, seems to be trying to prove this theory to Yang Yang, his roommate at a conservation center on Sado Island. It's apparently working.

"When You You tried to mount Yang Yang in an attempt to mate with her last month, she kicked him," said Masaharu Ono, who heads Niigata Prefecture's wildlife protection division.