Nest‑building chimpanzees seem to anticipate future weather

Fabiana Rizzi / Unsplash Hassan Al Razi, The University of Western Australia

Every evening, as they move from place to place through the forest, chimpanzees stop to build a nest – most often in a tree – to sleep in. Using a selection of branches, leaves and twigs, they create comfortable and safe spaces to get some shuteye.

Like human beds, these are places to rest – but they also help chimps stay warm or cool and protect themselves against the weather. As you might expect, how and where chimpanzees build their nests depends on things like temperature, humidity, wind and rainfall.

But how do they make these choices? Previous research has shown the construction is related to the conditions at the time when the creatures are building the nest.

In new research, published today in Current Biology, my colleagues and I show that chimps are a little bit cleverer than you might expect: they seem to build their nests in ways that anticipate what the overnight weather will be.

A year in Rwanda

We conducted a field study on eastern chimpanzees in Nyungwe National Park, Rwanda, a cool and humid mountain forest. Over a 12-month period, we collected detailed data on the structure of nests, the characteristics of their chosen sites, and the kinds of trees the chimps chose.

We also measured how well different kinds of nests insulate against cold and heat. At the same time, we made detailed records of weather conditions when the nests were being built and throughout the night.

This let us test whether chimpanzees respond primarily to immediate environmental conditions, or whether their nesting decisions are better explained by the conditions they experience later during the night.

Chimpanzees are always adjusting their behaviour

Our results show chimpanzees consistently adjust their nesting behaviour in relation to environmental conditions. They preferred to build nests in places that were warmer, more humid and less exposed to wind than surrounding areas.

Nest structure and insulation varied systematically with environmental conditions. In cooler and wetter conditions, nests were thicker and deeper – indicating the chimpanzees put more effort into insulation when conditions are tougher.

We also found that factors such as the width and depth of the nest influenced its insulating ability.

The chimpanzees tended to build more insulating nests when weather was colder and when it was more humid, both during nest-building and overnight.

In cooler and wetter conditions, the chimps also built their nests higher, in taller trees with denser leaf cover. This makes sense: it would be a more stable microclimate with more shelter from rain.

Are chimps thinking ahead?

Importantly, nesting decisions aligned more closely with overnight environmental conditions than with those at the time of construction. When we took overnight weather into account, we found we could explain the variation in nesting behaviour much better than if we used only the current conditions.

One possible explanation is that chimpanzees use environmental cues, such as shifts in temperature, humidity or atmospheric pressure, that are linked to upcoming weather.

These cues may allow them to adjust nest-building behaviour in advance. Does this mean they predict or forecast future weather? Not quite.

But it does show their behaviour is consistent with reacting to environmental signals that are associated with later conditions. Either way, the chimps display a remarkable sensitivity to their environment – and a grasp of how to live in it.

Hassan Al Razi, PhD Student, School of Human Sciences, The University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→May 01, 2026

Mozambique ‘sky island’ expeditions found 4 new species of chameleon – already at risk from forest loss

Male sylvan chameleon (Nadzikambia goodallae) from Mount Ribáuè, Mozambique. Krystal Tolley, CC BY Krystal Tolley, University of Johannesburg

Tropical rainforests are known for their unique biodiversity, with species found nowhere else on Earth. But nearly 30% of tropical rainforest has been destroyed or has become seriously degraded since 1990. Many of these forests have not been fully explored for their biodiversity. This means that the world may be losing species before they are even discovered by modern science.

In Africa, forest loss is rapid; about 25% of the continent’s tropical forest has been lost since 1990, against a backdrop of incomplete knowledge of where the biodiversity is located.

Greatly lagging in this respect are the “sky islands” of northern Mozambique: isolated granite mountains that rise sharply out of the savanna plains. They were left standing when softer rock around them gradually eroded, and can be as high as 3,000 metres elevation. Because they rise so steeply, the sky islands attract clouds and rainfall, feeding moisture to the tropical rainforests on their slopes within an otherwise arid terrain. Isolation has allowed unique species to evolve on each mountain, such as geckos, rodents, fishes, crabs, frogs, butterflies and bats.

Mount Inago. Krystal Tolley, CC BY

Small patch of remaining pristine rainforest at Mount Inago. Krystal Tolley, CC BY

From 2014 to 2018, a research team led by fellow herpetologist Werner Conradie and myself explored these sky island forests to catalogue the species of reptiles found there. We found that each sky island forest is home to a previously unknown species of chameleon within the genus Nadzikambia (forest-dwelling “sylvan chameleons”).

Unfortunately, these chameleons are already at risk of extinction due to the heavy slash-and-burn clearing of the forests, the only place they can call home.

We’ve described these new species, choosing four names to highlight pioneering women scientists whose work inspired us to strive towards new discoveries, but also to call attention to the losses of their forest habitat.

Hunting for chameleons

Over the course of several years, we explored four of Mozambique’s sky islands – Mount Namuli, Mount Inago, Mount Chiperone and Mount Ribáuè – with the aim of cataloguing all reptiles but also in the hopes of finding new species of chameleons. This was because a species of sylvan chameleon had been discovered on one of these mountains during the 1960s, but they were not known from any other mountains.

However, chameleons can be very difficult to find, given their ability to remain camouflaged against the background coupled with their slow movements. They are more easily spotted at night while they are sleeping, as they stand out against the vegetation when illuminated by a strong beam of light. Sylvan chameleons are even more difficult to spot than others, as they usually perch high in the thick forest canopy – tens of metres up.

The search meant dealing with some tough conditions: a long, arduous trek up the hot, arid slopes to reach the forest high up the mountain. Establishing a remote base camp was essential. All food, clothes and gear had to be packed into the camp, and we didn’t know how long it would take to find any animals.

At each of these mountains, we surveyed every night for chameleons – no trails to follow, no GPS signal to guide us, no cellphone signal to call for help.

Sometimes we were lucky and found chameleons on the first or second night. At other mountains we were not so lucky, with fruitless searches making it necessary to return another year.

Eventually these mountains revealed their secrets and we discovered four new species of sylvan chameleon, one on each of the four mountains.

Slash-and-burn clearing of rainforest at Mount Inago. Krystal Tolley, CC BY

We don’t know how big their populations are, but we assume they are in decline. Most of their habitat has been destroyed by forest clearing to make way for agriculture, with increasingly rapid losses in the last decade. We estimate that in some cases, 80%-90% of their habitat has been destroyed.

When parts of an ecosystem are lost, the whole becomes unstable and is eventually lost.

Choosing names for the new species

To highlight their predicament, we have described and named these chameleons and have forecast that three of these species are at high risk of extinction.

In particular, we highlight Nadzikambia goodallae from Mount Ribáuè. This species has been named in honour of the distinguished scientist Jane Goodall, whose own study species, the chimpanzee, is under similar pressures from loss of its rainforest habitat.

Female sylvan chameleon (Nadzikambia goodallae) from Mount Ribáuè. Krystal Tolley, CC BY

We also honour the renowned discoverer of the structure of DNA, Rosalind Franklin, by naming the species from Mount Namuli as Nadzikambia franklinae. The use of DNA data from these chameleons was essential to confirm them as new species.

Nadzikambia franklinae from Mount Namuli. Werner Conradie, CC BY

We have dubbed the species from Mount Inago as Nadzikambia evanescens, meaning “vanishing” in Latin, acknowledging the state of the forest destruction.

Male sylvan chameleon (Nadzikambia evanescens) from Mount Inago. Krystal Tolley, CC BY

The final species, Nadzikambia nubila, is named for the cloudy aspect of Mount Chiperone. This species has a lower risk of extinction given that the local community view the forest as sacred, and say it should be protected.

Female sylvan chameleon (Nadzikambia nubila) from Mount Chiperone. Krystal Tolley, CC BY

This latter case is significant, as it demonstrates that wholesale destruction of these forests is not an essential trade-off for local people to thrive. If encouraged and supported, community support and buy-in can be a solution to protect biodiversity in these sensitive ecosystems.

Krystal Tolley, Principal Scientist, University of Johannesburg

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→April 27, 2026