Never fall for the rats’ tricks. Cities may be thriving ecosystems for pizza-stealing nomads and other critters, but for many wild animals, the concrete and motor traffic make cities uninviting places to call home. Scientists have shown that when human development alters ecosystems, many species disappear and animal societies become less varied.
Cities vary greatly in their quality of life. According to a new research published in Nature Ecology & Evolution on Monday, urbanisation seems to have a bigger impact on wild animal populations in hotter, less vegetated regions than in colder, greener ones. The results indicate that urbanization’s negative impacts on wildlife might be magnified by climate change.
Scientists looked examined images captured by wildlife cameras placed in 725 locations across 20 cities in North America. Participating in the Urban Wildlife Information Network, a continuous effort to gather data on urban biodiversity, were the cities of Chicago, Phoenix, and Tacoma, Washington. The cameras were placed in a variety of public spaces around each city, from highly metropolitan areas like motorway and airport interchanges to less developed areas like parks and trails.
The scientists looked at the summertime photographs. Raccoons, squirrels, rabbits, foxes, cougars, and deer were just some of the 37 native animal species they saw.
Consistent with previous study, the team discovered that less urbanised areas had greater abundance and variety of wild animals. However, cities that were either relatively temperate or lush, with plenty of healthy, green plant life, proved to be better for animal adaptation than warmer, more arid ones.
For instance, as camera locations got increasingly urban, the variety of mammals drastically decreased in hot Los Angeles but just slightly decreased in cold Salt Lake City. While both Sanford, Florida and Phoenix, Arizona have mild winters and summers, Sanford is home to far more lush vegetation. The scientists discovered that urban regions of Sanford maintained a more diversified mammal community than urban parts of Phoenix.
Cities are known to trap heat, making them warmer than less developed places nearby, but the researchers have not yet determined what motivates these tendencies. This urban heat island effect may “just be making it harder and harder to live,” as Dr. Haight puts it, in places located in naturally warm climes. For animals in need of a warmer climate, the relative warmth of cities may be an attractive option.
Vegetation has the potential to provide urban wildlife both food and shelter. However, Dr. Haight noted that green cities are also often wetter places, which might make it simpler to access resources like water.
Researchers also discovered that larger species, such as cougars and elk, were more severely impacted by urbanisation than smaller animals. It might be because bigger animals need more room to move about. Dr. Haight noted that although urban areas can provide enough habitat, this space is typically fragmented. He also noted that people may be less tolerant of wild animals in urban areas.
The research was not without its flaws. It’s possible that other patterns might emerge in other locations or times of year, since cameras are not equally excellent at recognising all species and the scientists only analysed photographs from cities in North America in the summer.
However, as Dr. Rega-Brodsky points out, this study shows how human-caused environmental changes may have multiplicative consequences. It also suggests possible remedies, such as the provision of flora, water, and locations where animals may escape the heat in hot, desolate towns.
