Hundreds of mammals show how humans influence animal activity

Modern technology has changed the way humans observe wildlife. Mini cameras placed in backyards and natural landscapes now capture unexpected activities from the animal world. These tiny devices reveal the secret lives of creatures that often go unnoticed.

From bears rummaging through garbage bins to deer wandering suburban streets, these glimpses into nature have fascinated millions.

While these videos often go viral for entertainment, scientists have recognized their potential for research. A group at the University of Rhode Island has taken this idea further. They created a massive dataset of animal images, not just for curiosity, but for science.

The goal was to understand how animals behave at different times of the day and how human presence affects their activity patterns.

Studying the activity of 400 mammals

To build a more detailed picture of animal habits, researchers launched the Global Animal Diel Activity Project. They gathered data from 20,080 camera trap sites across 38 countries and six continents.

The study included over 400 mammal species, making it one of the largest camera-based research projects in existence.

This ambitious project involved more than 200 scientists worldwide. They analyzed 8.9 million animal observations to create a massive collection of activity estimates. The results were surprising.

Less than half of the species studied matched the activity classifications found in reference books. Many animals exhibited different behaviors than previously thought, challenging long-standing assumptions about their activity cycles.

The study was led by Brian Gerber, a research ecologist at Colorado State University, and Kadambari Devarajan, a research fellow at the University of Rhode Island.

The findings provide new insights into how animals adapt their behaviors based on environmental and human influences.

Unpredictable patterns in animal activity

The study revealed that many animals do not strictly follow diurnal or nocturnal behavior patterns. Instead, their activity changes based on location, environmental conditions, and human presence.

Gerber was surprised by the extent of this variation. “I expected some variation, but basically most species that we had adequate data on showed that they would change their diel activity.”

For example, American black bears did not follow a consistent schedule. In some locations, they were diurnal, meaning they were active during the day. In others, they were cathemeral, meaning their activity was scattered across both day and night.

This flexibility suggests that animals may not be as rigid in their routines as previously believed.

Global wildlife project

Gerber’s interest in diel activity began 18 years ago when he was studying fossas in Madagascar. He noticed that these animals did not always behave according to expected patterns. This observation led to years of curiosity about how different species adapt their activity to their surroundings.

By 2017, while working at the University of Rhode Island, Gerber developed a method to analyze diel activity across many species.

Collaborating with other researchers, he designed a large-scale study to explore how animal behavior changes in different environments.

The resulting dataset included species from a wide range of habitats, including deserts, rainforests, tundras, and savannas.

Human influence on animal behavior

One of the most significant findings of the study was the impact of human presence on animal activity. Researchers compared data from urban and wild areas to see how species responded to human influence.

They found that a third of the species studied altered their activity patterns in response to human development.

Some species became more nocturnal, likely to avoid human contact. Others adapted by becoming more diurnal, possibly to take advantage of new food sources or reduced predator threats. This shift in behavior demonstrates that animals are not just reacting to natural environmental changes but also to human activity.

Gerber explained how this discovery challenges traditional classifications. “The most striking thing is that when you are taught an animal is diurnal or is nocturnal, that is not always correct.”

“Many terrestrial mammals will be diurnal sometimes and nocturnal or cathemeral other times. When you see a nocturnal species during the day, this is perhaps not as unusual as you might think.”

Animal activity and external pressures

Conventional classifications label animals as diurnal, nocturnal, crepuscular (active during twilight), or cathemeral. These labels suggest that activity patterns are fixed traits. However, the research team found that these classifications are more fluid than previously thought.

Devarajan emphasized that animal behavior is shaped by both evolution and immediate environmental conditions. A species’ activity schedule is not simply a biological trait but also a response to external pressures.

Light availability, human development, and habitat changes all play a role in shaping when animals are active.

Shifts in animal activity

The study found that only 39% of the species studied matched their expected diel classification. This means that most animals showed flexibility in their behavior.

A striking 74% of species changed their activity patterns in response to human influence. For instance, the striped skunk, gray fox, North American porcupine, and snowshoe hare became more nocturnal in areas with higher human impact. This shift likely helps them avoid human disturbances and predators.

The team also discovered that light availability affected diel plasticity. In some cases, urban lighting caused nocturnal species to become more active during the day. This adaptation highlights the complex ways in which animals respond to their surroundings.

Implications for conservation

Understanding diel activity is essential for wildlife conservation. Animal activity patterns influence population tracking, conservation planning, and hunting regulations. Knowing when species are most active can help researchers develop better protection strategies.

As environmental changes accelerate, some species will adapt their activity patterns, while others may struggle. Gerber stressed the importance of recognizing how these shifts affect animal survival.

“Recognizing the fitness consequences of species’ diel phenotype plasticity and lack thereof is an important next step to understand the impacts of environmental change and can help direct conservation actions,” said Gerber.

This study provides a deeper understanding of how animals navigate a changing world. As habitats continue to shift, scientists must continue monitoring how species adapt.

The knowledge gained from projects like this can help guide future conservation efforts and ensure the survival of many species.

The study is published in the journal Science Advances.

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