Male Humboldt penguin pair "Sechs Punkt" (Six Point) and "Schraegstrich" (Slash) cuddling at the Bremerhaven

Six gay penguins at a German zoo are still refusing to mate with
females of the species flown in from Sweden in 2005, the zoo said.

The problem was that the female Humboldt penguins have proven too shy
in their advances, the director of the zoo in the northern port city of
Bremerhaven said.

"The Swedes will not make the first move," Heike Kueck said.

The females were flown in last year in a bid to bring the males to mate
and help save the Humboldt species from extinction.

Kueck said last year she was optimistic the initiative would be
successful because zoo keepers had noticed that at one point a female
penguin had managed to cause a couple of males to "separate".

The zoo has 10 male penguins of which six have shown strong signs of
preferring male company and formed couples among themselves.

The initiative to "turn" the penguins and make them mate had
prompted a furious response from gay rights groups.

In a statement posted on its Internet website, the zoo on Wednesday
sought to defend itself from fresh criticism.

"We will be delighted if the penguins form even one heterosexual
couple and manage to produce first an egg, and then a little one," it
said.

"But of course we accept the male couples that have formed and we
are not trying to enforce heterosexuality, as we were accused of doing
last year."