Giraffes should be listed as officially endangered in order to preserve their dwindling numbers, conservationists have said, following a warning the animals are facing a "silent extinction".

The number of giraffes in sub-Saharan Africa has dropped by around 40 per cent since the mid-1980s and environmental groups now want the creatures to receive special protection, including by the influential US Fish and Wildlife Service.

According to the International Union for the Conservation of Nature, just 97,500 wild giraffes remain, pushing their population below that of the African elephant.

That compares with a population 15 years ago that was judged to number around 150,000.

Jeff Flocken, North America regional director of the International Fund for Animal Welfare, said: “When I was doing research on giraffes in Kenya a few years ago, they were quite abundant and no one questioned that they were doing well.

“Only recently have we looked at them critically and seen this huge drop, which has been a shock to the conservation community. This is an iconic animal and it’s in deep trouble.”

Sir David Attenborough has been a vocal advocate of protecting giraffes, warning that “time is running out” for the animals, which have become extinct in seven countries already.

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The petition says the US is “uniquely positioned to help conserve these tall, graceful and iconic animals”.

“Now is the time for Endangered Species Act protections for this seriously and increasingly imperilled species,” it adds.