Deforestation threatens the future of 8 in 10 lizards

In the high temperatures of Colorado’s summer, the Rocky Mountains become a sought-after retreat for both humans and animals. This is particularly true for lizards and other small, tree-dwelling animals, which utilize forests as vital shelters from the heat. 

A recent study led by a team of  researchers from the University of Colorado Boulder (CU) and Tel Aviv University in Israel outlines a concerning future for North American lizards in the face of deforestation and climate change. It is estimated that 84% of these reptiles could suffer negatively by the century’s end, with a significant portion at risk of population decline.

Unique vulnerability of lizards

The study highlights the unique vulnerability of lizards, as cold-blooded animals, to environmental temperature changes. Unlike mammals, which have a variety of methods to regulate their body temperature, lizards are dependent on their surroundings to warm up or cool down. 

“What’s really interesting about lizards is that they just need to be able to move a short distance around the tree trunk to get to a very different climate and habitat environment,” explained Keith Musselman, an assistant professor in the Department of Geography and CU Boulder’s Institute of Arctic and Alpine Research. “These microhabitats are particularly important when we think about how we modify our natural environment and make conservation decisions.” 

Impacts of deforestation

Through computer simulations, the research team was able to demonstrate that while global warming could have potential benefits for lizards in colder or higher latitude areas by extending their daily active periods, deforestation could negate these benefits by removing crucial sources of shade. 

The findings suggest tree loss could reduce lizards’ active time by an average of 34% by century’s end, forcing these reptiles to seek alternative cooling shelters and significantly affecting those in warmer climates where future summers may be too intense for ground-level activity.

Accelerated decline of lizards 

The study projects that an estimated 18% of North American lizard populations could experience accelerated decline due to deforestation. 

“Our work provides new insights into the mechanisms by which deforestation may cause population declines in the face of climate change,” said Ofir Levy, a zoologist and Musselman’s collaborator at Tel Aviv. “The decline in lizards can lead to a cascading effect as they are an important part of almost every ecological system.” 

Alarming pace of deforestation 

Despite international commitments to stop deforestation, it continues at an alarming pace, with approximately 459 million hectares, or 12%, of the world’s tree cover lost from 2001 to 2022. 

“Deforestation is a worldwide problem, and our conclusions can help decision-makers on other continents in designing conservation and habitat restoration programs that consider climate change,” said lead author Omer Zlotnick, a PhD student at the same university.

Lizards depend on the local landscape 

The study also draws attention to the specific challenges faced by small animals, such as lizards, that cannot migrate long distances to escape the heat. 

“Here in the Rocky Mountains, elevation provides an escape for animals that can travel longer distances, including us humans. On those summer days when it hits 100 degrees, many of us will go into the mountains. But small animals like lizards can’t travel far. They heavily depend on the refuge provided by the local landscape, including tree trunks,” noted Musselman.

“The study highlighted the importance of understanding which elements in the environment can serve as refuges for other organisms on this planet.”

The study is published in the journal Nature Climate Change.

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