A lonely monkey at an Israeli zoo has found a way to soothe her maternal urges: by adopting a chicken.

Niv, an Indonesian black macaque, has spent the past week caressing, cleaning and playing with the bird at the Ramat Gan Safari Park near Tel Aviv.

"It seems that Niv, who is four years old and has reached the age of sexual maturity, has difficulty finding a partner," the zoo's spokeswoman Mor Porat said.

"This probably explains the maternal instinct she expresses to this chicken."

The bird, which doesn't have a name, could easily escape through the bars but chooses to stay near Niv.

"These kinds of relationships are rare," Porat told AFP. "Sometimes macaques kill and eat chickens that enter their pens or play with them until they die."

To avoid such a tragic end, officials separated Niv and her feathered companion from the other macaques -- apart from her mother, who is often the target of hostilities from other females.

Porat said the chicken "seems very happy to have found a surrogate mother. At night they sleep together."

A few months ago, Niv attempted to adopt a previous chicken, but it spurned her advances. 

Seemingly unlikely animal friendships are often the result of different species being put together by humans.

A bear, lion and tiger discovered during a drug raid in the United States remained inseparable for life after they were moved to an animal sanctuary.

But Porat said it wasn't clear where the chickens at the zoo had come from.

The black macaque is listed as critically endangered by the International Union for the Conservation of Nature. 

The domesticated chicken is the most common bird in the world.