Catastrophic species loss in Okavango delta

The Okavango delta is one of the wonders of the natural world. The 16,000km oasis in the Kalhari desert, Botswana, is made up of around 50,000 islands intersected by channels, lagoons, and swamps Photograph: Kelly Landen/Elephants without Borders

Elephants without Borders conduct regular aerial surveys of wildlife the Okavango delta. Their most recent survey has recorded catastrophic species loss, the worst affected species have suffered population decline of over 90% Photograph: Kelly Landen/Elephants without Borders

Note the two digital cameras mounted on each side. Photographing packs of animals from the air is a reliable way to survey populations Photograph: Kelly Landen/Elephants without Borders

A herd of buffalo in the Okavango delta Photograph: Kelly Landen/Elephants without Borders

Drought, habitat encroachment, bushfire, and poaching are the main causes of the catastrophic species loss which has been seen in the Okavango delta Photograph: Kelly Landen/Elephants without Borders

90% of the Wildebeest population in the Okavango delta has been wiped out since the last aerial survey in 1996 Photograph: Kelly Landen/Elephants without Borders

The red lechwe is popular with poachers - its population has declined by half over the past 10 years Photograph: Kelly Landen/Elephants without Borders

There is some good news - the hippo population has increased by 6% this year Photograph: Kelly Landen/Elephants without Borders

More good news - the elephant population in the Okavango delta remains stable at 130,000. But other animals haven't done so well. The kudu population is down by 81% since 1996, ostrichs by 95%, tsessebes by 84%, while the number of giraffees has fallen by two thirds Photograph: Kelly Landen/Elephants without Borders