Two rare Eastern Black Rhino calves were born within days of each other at the Chester Zoo, boosting global numbers of the Critically Endangered species.

The new mothers, Kitani and Zuri, delivered their babies on June 19 and June 26 after 15-month-long pregnancies. The babies were delivered safely onto soft sand.

Photo Credit:  Chester Zoo

Video footage shows Kitani spinning around as she delivers her calf. The youngster was on its feet within a few minutes of birth, and took its first wobbly steps as amazed zoo visitors watched.

Both calves are doing well, and Kitani and Zuri are excellent mothers, according to their care team at Chester Zoo.

Less than 650 Eastern Black Rhinos now remain across Africa, and the International Union for the Conservation of Nature (IUCN) lists the animals as Critically Endangered in the wild.

The two births are a boost for the endangered species breeding program for Eastern Black Rhinos, which are teetering on the brink of extinction in the wild. Zoo births are managed to retain the highest level of genetic diversity as a hedge against possible extinction in the wild.

In addition, knowledge obtained from the zoo’s Rhino breeding program is being used right now in Africa to boost conservation efforts in the field.  

A huge surge in illegal poaching, driven by a global increase in demand for Rhino horn to supply the traditional Asian medicine market, resulted in around 95% of Rhinos being wiped out since the turn of the 20th century. 2014 was branded ‘the worst poaching year on record’ by leading conservationists after more than 1,200 Rhinos were hunted in South Africa alone - a 9,000% increase from 2007.

The issue is being driven by the street value of Rhino horn, which sells for more per gram than gold or cocaine, although modern science has proven it completely useless for medicinal purposes.  Rhino horn is made from keratin – the same material as human hair and nails.

See more photos of the calves below.