Unfortunately— humans did it again. Two subspecies of giraffes have been added to the list of endangered species as they're on the brink of extinction, mainly because we've destroyed their habitats.

With its spindly legs, distinctive patterning, and absurdly long neck, the giraffe is the tallest mammal in the world.

However, the population of this startling animal has dropped significantly over the last few decades. From around 150,000 in 1985 to less than 100,000 today.

As reported by the International Union for Conservation of Nature (IUCN), the numbers of mammals have decreased by 40 percent over the last three decades.

The Kordofan and Nubian giraffe subspecies — found mainly across East, Central, and West Africa — are now classified as "critically endangered," while the reticulated giraffe — native to the Horn of Africa — is listed as "endangered," according to reports.

As a result, the subspecies were moved from the list of "Least Concern" to "Vulnerable" in its Red List of Threatened Species.

There're seven other giraffe subspecies worldwide. Each category is struggling to increase its population due to human activities.

Like most environmental problems facing our natural wild, humans are at the root of it all.

In addition to illegal poaching and civil unrest in some parts of the African continent, loss of habitat due to agriculture and mining is one of the biggest threats to the species.

Dr. Julian Fennessy, the co-chair of the IUCN Special Survival Commission, said in a statement:

"Whilst giraffes are commonly seen on safari, in the media, and in zoos, people, including conservationists, are unaware that these majestic animals are undergoing a silent extinction."

"While giraffe populations in southern Africa are doing just fine, the world's tallest animal is under severe pressure in some of its core ranges across East, Central, and West Africa."

"It may come as a shock that three of the currently recognized nine subspecies are now considered 'Critically Endangered' or 'Endangered,' but we have sounded the alarm for a few years now."

Some food insecure communities kill giraffes for their meat. Most of these animals are slaughtered for their tails, which are considered a status symbol in some cultures and used as part of the dowry when asking a bride's father for his daughter's hand.

It seems the African elephant and rhino aren't the only targets of poachers, as giraffes also attract them. Giraffe's heads and bones can be sold for up to $140 each.

We need to raise awareness of this serious issue before the world's tallest mammals go extinct.