How did quaggas become extinct?

Answer 1

The quagga had been hunted to extinction for meat, hides, and to preserve feed for domesticated stock. The last wild quagga was probably shot in the late 1870s, and the last specimen in captivity, a mare, died on 12th August 1883. Because of the great confusion between different zebra species, particularly among the general public, the quagga had become extinct before it was realized that it appeared to be a separate species

Answer 2

The following is a quote from the main Wikipedia website.

The quagga was originally classified as an individual species, Equus quagga, in 1778. Over the next 50 years or so, many other zebras were described by naturalists and explorers. Because of the great variation in coat patterns (no two zebras are alike), taxonomists were left with a great number of described "species", and no easy way to tell which of these were true species, which were subspecies, and which were simply natural variants.

Long before this confusion was sorted out, the quagga had been hunted to extinction for meat, hides, and to preserve feed for domesticated stock. The last wild quagga was probably shot in the late 1870s, and the last specimen in captivity, a mare, died on August 12, 1883 at the Natura Artis Magistra zoo in Amsterdam. Because of the confusion between different zebra species, particularly among the general public, the quagga had become extinct before it was realized that it may have been a separate species.

However, there are projects to try and 'bring them back' by introducing their DNA to horses.