The short answer is that leeches need blood to grow and reproduce. But it's in their interests to do it carefully, without causing too much pain, and in spots that are hard to find.
Zooming in on deforestation and other wild habitat loss can help us work out how best to protect wilderness.
A recent spate of attacks have left local people scared for their safety in rural Madagascar, threatening vital conservation work in the nearby rainforest.
Rainforests may have played far more of a role in shaping human evolution than previously thought.
Brazil has set itself a target of restoring almost 50,000 sq km of the Amazon rainforest by 2030. But it won't get there without changing its policies and how it engages with local people.
Conservationists scaled the sheer cliffs of Mount Lico as part of wider effort to build the case for the protection of Mozambique's mountain forests.
It's hard to measure the value of a tree, but scientists equipped with lasers have come one step closer.
Three researchers studied the "crop raiders" of the Brazilian rainforest in the hope of aiding both local farmers and wildlife conservation.
The history of the rubber 'boom' reveals why.
Forest fires emit twice as much carbon in the Brazilian Amazon as deforestation, according to new research.
A drying climate caused a mass extinction among plants, but paved the way for the ancestors of modern reptiles, mammals, and birds.
They are contesting the maps that deny them territorial rights.
Some leaves are millimetres across, and others are a metre square. An international study has found the essential factors controlling leaf variations.
It's crucial to know the relationship between biodiversity and carbon storage to assess whether carbon-focused conservation will also protect the most biodiverse forests.
Tiny frogs that have spread across New Guinea's isolated mountains could face an uncertain future if a warming climate pushes them higher up the peaks.
Combining new technologies, including Global Forest Watch, a Forest Monitoring App and Participatory 3D Modelling, brings out traditional knowledge of the elders.
New research shows how ancient rainforest cultures have left their mark on today's plantlife.
Metallic starlings – not the kind that live in your roof – breed in huge colonies that draw thousands of animals.
The world has lost 10% of its wilderness areas in the past 20 years and, with it, vast stores of carbon.
Queensland's Wet Tropics are home to a dizzying range of plant and animal species, but are at risk of being overrun by yellow crazy ants.