Visitors to Vienna’s Haus des Meeres can celebrate the birth of a baby monkey. The cotton-top tamarins have welcomed offspring again this year, the zoo announced Wednesday. “Born on Friday the 13th, jet-black but no bad omen—in fact already a top favorite among our guests,” said curator Robert Riener.

Cotton-top tamarins are small, tree-dwelling primates about 20 cm long, living in groups of up to ten in South American forests. At Haus des Meeres, they reside in the tropical house.

At first, patience is required: for the first three weeks the infant clings to its mother’s back, nestled tightly in her soft fur. Only afterward may the father and other group members carry the youngster—sometimes leaping up to four meters between branches.

“Although known to science for only about 120 years, cotton-top tamarins are now endangered,” said zoo director Jeff Schreiner. “That’s why we participate in the European Endangered Species Programme (EEP) to breed them responsibly.”