ALBUQUERQUE, N.M.—Officials at the Albuquerque BioPark say a baby orangutan that was born at the zoo this week is alert, has been nursing and has a strong grip.

The zoo says Sarah the Sumatran orangutan gave birth to the healthy baby sometime late Thursday or early Friday. Zookeepers have yet to determine the baby's gender.

They say Sarah and her baby are behind the scenes but will soon rejoin the rest of the orangutans.

The zoo's primate supervisor, Debbie Wiese, says the first few days after birth are the most critical and the mother and baby will be closely monitored to make sure development progresses normally.

Sarah's pregnancy surprised zookeepers last November, making it difficult to determine a due date.

This is the first orangutan birth at the zoo since 2008.