Peering through enclosure windows, they were a popular source of entertainment at Jerusalem's Biblical Zoo.
But the human visitors haven't been around for a month, since the start of a national coronavirus lockdown in Israel – and the animals miss staring at them, zoo keepers say.
"They are sitting above, they are playing with each other," Nili Avni-Magen, the zoo's head veterinarian, said at the primates' enclosure. "We are trying to do enrichments but they are missing the visitors in the big front window."
A sprawling site in Jerusalem, the zoo contains a wide variety of animals but gives pride of place to species mentioned in the bible.
With no visitors around, the animals must make do with interacting with their keepers, who are busy feeding and tending to kangaroos, zebras and elephants.
When a Reuters television crew toured the zoo, black-and- gold howler monkeys came out of their house, eager to take a look.
"They are really missing it," Avni-Magen said about the daily interaction with visitors. "They are sitting and waiting that the zoo will open again."
The lions, however, seem to be an exception, sidling closer to their keepers and the front areas of their compound now that the crowds are gone.
"They feel more secure when they see less people," Avni-Magen said.