Orangutan gives birth after negative pregnancy test, inseparable from her baby

PEOPLE – This baby knows how to make an entrance! The Chester Zoo recently welcomed a critically endangered Bornean orangutan baby, a joyous and somewhat shocking event.

The new arrival took keepers at the English zoo by surprise because the baby’s mom, Leia, took a pregnancy test and received negative results just months before the birth. According to the Chester Zoo, a typical orangutan pregnancy lasts about eight and a half months, so the results of the test should’ve come back positive.

More details on Thursday’s Borneo Bulletin