About 60% of giant herbivores - plant-eaters - including rhinos, elephants and gorillas, are at risk of extinction, according to research.

Analysis of 74 herbivore species, published in Science Advances, blamed poaching and habitat loss.

A previous study of large carnivores showed similar declines.

Prof William Ripple, of Oregon State University, led the research looking at herbivores weighing over 100kg, from the reindeer up to the African elephant.

"This is the first time anyone has analysed all of these species as a whole," he said.

"The process of declining animals is causing an empty landscape in the forest, savannah, grasslands and desert."

The threatened mountain zebra

Prof David Macdonald, of Oxford University's Wildlife Conservation Research Unit, was among the team of 15 international scientists.

"The big carnivores, like the charismatic big cats or wolves, face horrendous problems from direct persecution, over-hunting and habitat loss, but our new study adds another nail to their coffin - the empty larder," he said.

"It's no use having habitat if there's nothing left to eat in it."

According to the research, the decline is being driven by a number of factors including habitat loss, hunting for meat or body parts, and competition for food and resources with livestock.

World's reptiles at risk of extinction

Many lizards are under threat, including the mountain horned agama of Sri Lanka

Almost a fifth of the world's reptile species are at risk of extinction, according to scientists.

Research led by the Zoological Society of London found that the future of 19% of the world's reptiles are threatened. Conservation experts also confirmed that 47% are vulnerable and highlighted the possible extinction of three species. The figures are based on a random sample of 1,500 of the world's reptile species. "It's essentially an election poll set up - using this sample to give an example of how reptiles are doing as a whole," explained Dr Monika Bohm, lead author of the study published in the journal Biological Conservation. The study was made in conjunction with 200 experts from the International Union for the Conservation of Nature's Species Survival Commission.

Rarest dog: Ethiopian wolves are genetically vulnerable

Populations of the world's rarest dog, the Ethiopian wolf, are genetically fragmenting, scientists say.

Fewer than 500 of Africa's only wolf species are thought to survive. Now a 12-year study of Ethiopian wolves living in the Ethiopian highlands has found there is little gene flow between the small remaining populations. That places the wolves at greater risk of extinction from disease, or habitat degradation. In a study published in the journal , Dada Gottelli of the Zoological Society of London and colleagues in Oxford, UK and Berlin, Germany, quantified the genetic diversity, population structure and patterns of gene flow among 72 wild-living Ethiopian wolves.

 
Red dog

This inhospitable-looking landscape is home to some critically endangered species. The Niger government, this month, formally decreed this whole area - the Termit Massif and Tin Toumma desert - to be a national nature and cultural reserve. At almost 100,000 square kilometres it is the largest single protected area in Africa.   One of Earth's most inhospitable deserts is an important stop-over for migrating wildlife, scientists say. Researchers working in the Termit Massif and Tin Toumma desert in Niger say the whole area should be protected, because it is a biodiversity "hotspot". The rocky massif is home to the Critically Endangered dama gazelle.

The elusive Saharan cheetah, captured here by a camera trap, also lives there. Scientists working for the Sahara Conservation Fund (SCF) are working to have the area declared a National Reserve. The rainy season transforms the arid landscape into a temporary wetland, which many migrating animals depend on.