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

How birds are spreading plastic pollution

White storks and gulls feeding at a landfill. Enrique García Muñoz (FotoConCiencia), CC BY-NC-ND

Andy J. Green, Estación Biológica de Doñana (EBD-CSIC); Manchester Metropolitan University

Hungry gulls do not only steal our chips and sandwiches. They learn our habits, and look for reliable sources of food. That includes waste treatment centres, landfill or anywhere food waste is concentrated. Many gull populations have moved inland from the coast to exploit these sources of food.

Wherever our waste is processed, gulls and other birds can forage. At landfills, gulls feed on waste before it is covered up. If there are plastic or glass pieces covered in food that are small enough, gulls will swallow them whole. Only the food itself gets digested, and when the gull flies back to its roost site, the waste gets regurgitated, polluting that site. This movement of pollutants is known as “biovectoring”.

For the first time, scientists like me are now quantifying just how much plastic and other waste is being leaked into important nature areas through the daily movements of birds.

Many lesser black-backed gulls breeding in the UK and other parts of northern Europe migrate to Andalusia in southern Spain, where they form a wintering population of over 100,000 feeding mainly in rice fields and landfills. Fortunately, many of these birds are fitted with GPS tags while breeding. This enables detailed tracking of their movements.

Fuente de Piedra lake in Málaga is a hotspot for migrating lesser black-backed gulls. This wetland has such special natural significance, it’s designated as an internationally important site under a global convention known as Ramsar. It’s most famous for the largest breeding colony of flamingos in Spain. Gulls fly up to 50 miles to landfills to feed, then fly back to roost.

By combining GPS data with waterbird counts, and analyses of regurgitated pellets, scientists have estimated that an average of 400kg of plastics, plus more than two tonnes of other debris such as glass, textiles or ceramics, are deposited by this gull species into the lake each year. This lake has no outflow, making it salty and hence flamingo friendly. Those imported plastics remain in the lake, breaking down into microplastics. They can be ingested by flamingo chicks, aquatic insects and other animals.

Two yellow-legged gulls chase a white stork that is carrying plastic in its bill, which it picked up at a landfill. Enrique García Muñoz (FotoConCiencia), CC BY-NC-ND

In coastal Andalusia, these gulls join the resident yellow-legged gulls (equivalent to our herring gulls) and a mixture of migratory and resident white storks as the three major waterbird visitors to landfills.

In the Cádiz Bay wetlands (another Ramsar site), surrounding the historical city that is now a favourite stop for cruise ships, the three species combine to spread different types and sizes of plastics into different microhabitats. Annually, 530kg of plastics are deposited into wetlands via regurgitated pellets. Although a stork is bigger, so transports more waste per bird, most of the plastic is again moved by the lesser black-backed gulls that winter there in larger numbers.

Plastic film regurgitated by a gull roosting in a field in Atherton, Greater Manchester. Kane Brides, CC BY-NC-ND

This waste ingestion has strong effects on the birds themselves, through direct mortality from diseases, choking or becoming entangled with plastics, and toxic effects of the additives within them. Then after regurgitation in pellets, those plastics are a threat to all fauna and readily enter our food supply through aquaculture and table salt production, both important in Cádiz Bay.

These studies in Spain address a problem that is ongoing all over Europe. There are no comparable quantitative studies yet in the UK, but similar problems occur wherever gulls concentrate to feed on our waste. If white storks become abundant in the UK future, they will probably visit our landfills, together with gulls and perhaps cattle egrets.

The sealing of many landfills, and improvements in waste management may have contributed to recent declines in many gull populations in the UK and elsewhere. But these problems of plastic leakage will continue so long as our consumer society generates so much waste. Reducing waste, and reusing things is better than recycling, partly because food containers may get eaten by birds before they can be recycled. Cleaning our food containers before we bin them, and composting our own food waste, can also help to reduce this phenomenon.

Andy J. Green, Professor of Freshwater Ecology, Estación Biológica de Doñana (EBD-CSIC); Manchester Metropolitan University

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

Read More........→March 28, 2026