Images of an American hunter posing with the body of a black giraffe she killed in South Africa have triggered an online backlash after going viral on social media.

Thousands of Twitter users expressed outrage at Tess Thompson Talley, 37, for killing the giraffe on a hunting trip last summer.

“Prayers for my once in a lifetime dream hunt came true today! Spotted this rare black giraffe bull and stalked him for quite awhile,” Talley wrote in a since-deleted post on Facebook.

The post said the animal was more than 18 years old, weighed 4,000 lbs and yielded 2,000 lbs of meat. On average, giraffes have a 25-year lifespan.

The hunter defended herself, claiming she shot the giraffe because it had been killing other, younger bulls.

She told CBS News the giraffe was "beyond breeding age, yet had killed three younger bulls...now that the giraffe is gone, the younger bulls are able to breed".

She added: "This is called conservation through game management. The numbers of this sub-species is actually increasing due, in part, to hunters and conservation efforts paid for in large part by big game hunting.

"The breed is not rare in any way other than it was very old. Giraffes get darker with age."