Â鶹´«Ã½

News — Camera trap data collected by a  researcher helped power one of the largest global studies of mammal behavior to date — analyzing more than 8.9 million images across 445 species in 38 countries.

Published in , the study found that many species do not stick to a single daily rhythm, contradicting decades of scientific assumptions. These findings reveal the flexibility of wildlife and signal the need for a new framework to understand animal activity in a rapidly changing world.

What is diel activity?

Mammals’ daily schedules — how wildlife activity is spread over a 24-hour cycle based on light availability — are grouped into four categories known as a diel phenotypes, said Humberto Perotto, Ph.D., associate professor and Joan Negley Kelleher Endowed Professor in Ranch Management in the 

• Diurnal animals are most active during the day.
• Nocturnal animals are most active at night.
• Crepuscular species are typically active during the dawn and dusk.
• Cathemeral animals show irregular activity throughout the day and night. 

Research born out of curiosity and anecdotal data

Perotto said researchers have long suspected wildlife species weren’t restricted to these specific four categories, especially with the advent of new technology like GPS collars used to collect regular animal movement data.

“Our argument was largely based on anecdotal evidence, but this research project truly quantifies that wildlife species don’t fit specifically within these parameters, and our changing environment influences their activity,” Perotto said.  

Perotto first learned of the project, led by researchers at the University of Rhode Island, while studying Rio Grande wild turkey in the Edwards Plateau.

“We had close to 56 camera traps set for our work, so we were collecting a lot of data not just on turkeys, but any number of wildlife that happened to pass through,” Perotto said.

After conversations with the project team in Rhode Island, Perotto and his students began reviewing their extensive data set and contributing to the .

Surprising insights about mammals’ behavior

The lead researchers analyzed the vast data set based on species, location, daylight length and geography and then compared their findings to published research indicating a species’ diel phenotype.

Of the 445 species documented, the analysis found that only 39% of the established diel phenotypes were accurate, and that species commonly use more than one diel classification.

“The most striking thing is that when you are taught an animal is diurnal or is nocturnal, that is not always correct,” said Brian Gerber, Ph.D., former University of Rhode Island research ecologist and project co-author. “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.”

Factors like body size, location and human presence were all found to shape diel activity patterns.

Human impacts shift animal behavior patterns

One of the clear trends found: Mammals in North America became more nocturnal in areas with higher human development.

“As we humans develop land and encroach into wildlife habitat, this land-use change causes new behaviors in wildlife,” Perotto said.

These changes may not always be harmless. For example, a species that typically forages during the daytime hours may have less success in finding food if they transition to more nocturnal behavior to avoid humans.

Conservation and management implications

Perotto said understanding these shifts is crucial for managing wildlife in a human-altered landscape.

“Further research is needed to better understand these implications and identify ways to mitigate potentially negative impacts,” he said. “Studies like this are advancing science and helping us understand how our changing world affects the rhythms of the natural world.”