Two male penguins at Toronto Zoo, who are thought to be in a relationship, are set to be split up in the coming weeks because they belong to an endangered species, says the Toronto Star.

Buddy, 20, and Pedro, 10, show signs of mating behaviour, or “pair bonding’’, but their relationship will end as the pair are introduced to females for mating.

The African penguin is endangered with fewer than a quarter of a million individuals left, and the zoo aims to increase its numbers.

The pair, born in captivity, arrived in May and their relationship has blossomed, the paper reports.

A zookeeper told the Toronto Star: “They do courtship and mating behaviours that females and males would do.”

It is one of many reported cases of same-sex coupling in penguins. Two male chinstrap penguins at New York’s Central Park zoo incubated an egg together and raised the chick, named Tango, when she hatched.

The penguins, Roy and Silo, had been attempting to hatch a rock, which was replaced with an egg by zoo staff.

A children’s book about them called And Tango Makes Three was a best seller that continually courted controversy and this year made it back to the top of the list of America’s most complained-about books.

Joe Torzsok, chair of the Toronto zoo board, said of Buddy and Pedro: “It’s a complicated issue, but they seem to be in a loving relationship of some sort”.