Extreme heat is harder on birds in the forest than in the city

Urban areas are often hotter than surrounding countryside. Cities both produce heat as well as trap it with man-made materials like concrete and asphalt, creating “heat islands.” There’s a well known record of people dying during extreme heat events pushed to greater highs due to urban heat islands. 

Researchers wondered what impact urban heat has on wildlife, specifically birds. In a new study published by Frontiers, experts have investigated the impact of extreme heat events on urban and forest dwelling great tits (a common songbird). 

“Our results suggest that natural populations may be more vulnerable to more frequent extreme heat,” said study lead author Dr. Ivett Pipoly of the University of Pannonia.

“We already know several environmental changes that urban populations have adapted, or are adapting, to in cities. It is interesting that urban individuals might adapt better to the climate crisis as well, maybe because they have more experience with heat as they live inside the urban heat island.”

The scientists installed hundreds of nest boxes throughout two Hungarian cities and adjoining forests. From 2013 to 2018, the scientists watched 760 broods, measuring chicks at two weeks old and then recording their survival. 

Counterintuitively, chicks in the hotter cities survived the extreme heat events better than their forest dwelling counterparts. Urban birds even showed a small benefit from the heat, while forest birds were smaller and less likely to survive.  

The mechanism behind this surprising increased survival of city birds isn’t yet known, and raises more questions than answers. The research also points to the fragility of birds as well as other animals in the face of human caused destruction. 

“We could hear about more frequent mass mortality events of wild desert birds, bats and even large herbivores nowadays, which could be a consequence of the vulnerability of natural populations to high temperatures,” said Dr. Pipoly.

“It will be extremely important to get more knowledge about the less conspicuous effects of extreme weather events, like the ones we found in great tits, and from several populations with different local environments. Then we can see a more detailed picture of the interactive effects of climate change and urbanization on wildlife and biodiversity.”

The study is published in the journal Frontiers in Ecology and Evolution.

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By Zach Fitzner, Earth.com Staff Writer