New research has found that chimpanzees build sleeping nests based on the weather conditions they anticipate for the night.
Every night, while moving through the forest, chimpanzees stop to build a nest – usually in a tree – to sleep. Using a selection of twigs, leaves and twigs, they create comfortable and safe spaces to rest.
Like human beds, these nests are used for resting, but they also help chimpanzees to stay warm or cool and protect themselves from the weather. As you can imagine, the shape and location of chimpanzee nests depend on factors such as temperature, humidity, wind and rain.
But how do they make these choices? Previous research has shown that construction is related to climatic conditions at the time of construction.
In new research, in Current Biology, scientists show that chimps are a little smarter than you might think: They seem to build their nests in ways that anticipate weather conditions of the night.
A year in Rwanda
The field study was conducted with eastern chimpanzees in Rwanda’s Nyungwe National Park, a cold, humid mountain forest. Over a 12-month period, scientists collected detailed data on nest structurethe characteristics of the chosen locations and the types of trees selected by the chimpanzees.
They also measured the thermal insulation capacity of different types of nests, both against cold and heat. At the same time, they recorded in detail the weather conditions during nest construction and throughout the night.
This allowed us to test whether chimpanzees respond primarily to immediate environmental conditions or whether their nest-building decisions are better explained by the conditions they face later in the night.
Chimpanzees are always adjusting their behavior
The results show that chimpanzees consistently adjust their behavior of nest construction in relation to environmental conditions. They preferred to build nests in places that were warmer, more humid and less exposed to wind than the surrounding areas.
Nest structure and isolation varied systematically with environmental conditions. In colder, wetter conditions, nests were thicker and deeperindicating that chimpanzees put more effort into thermal insulation when conditions are more adverse.
It was also found that factors such as the width and depth of the nest influenced its insulation capacity.
Chimpanzees tended to build more insulating nests when the weather was colder and wetterboth during nest construction and at night.
In cooler, wetter conditions, chimpanzees also built their nests higher, in taller trees with denser leaf cover. This makes sense: it would be a more stable microclimate, with more protection against rain.
Do chimpanzees think about the future?
It is important to highlight that decisions about nest construction were more aligned with nighttime environmental conditions than with the conditions at the time of construction. Taking nighttime weather into account could explain variation in nest-building behavior much better than using current conditions alone.
One possible explanation is that chimpanzees use environmental cuessuch as changes in temperature, humidity or atmospheric pressure, which are linked to future climate.
These clues may allow them adjust nest building behavior in advance. Does this mean they predict or anticipate future climate? Not exactly.
But this demonstrates that their behavior is consistent with reacting to environmental cues associated with later conditions. Either way, chimpanzees exhibit a remarkable sensitivity to their environment – and an understanding of how to live in it.
