The Rats Don’t Run the City, the Heat Does
If you have been to any major city, I’m almost certain that you have run into what many like to call your average “city rat”. However, you might have mistaken them for something much larger, such as a squirrel or raccoon, as they tend to be exceptionally bigger than your typical non-urbanized rodent. Arianne Cohen, journalist for the Fast Company, put it best in her recent article entitled “Nothing to see here. Just city rats getting bigger and bigger”, when she explains that she wouldn’t be surprised if you ran into one of these rats and say, “jumped onto a car hood … or took a quarter-mile detour when a gargantuan rat emerged from a sidewalk garbage bag and sped fearlessly in your direction” (Cohen, 2021). These common encounters have distorted one’s perception of these urbanized rodents, yet they ultimately operate with the same purpose as humans, trying to find food, water, and shelter, and are often affected by the same issues that we face today, with one major problem being the process of the urban heat island effect.
If you haven’t heard of this process, it majorly deals with the increased temperatures that many heavily urbanized areas face through the effects of global warming and climate change. Chelsea Harvey journalist for the Scientific American, an award-winning authoritative scientific media outlet noted in her recent article titled “Urban Heat Islands Mean Warming Will Be Worse in Cities”, that “the ‘urban heat island’ effect, can raise temperatures in cities by several degrees compared with their surroundings, [creating] a risk to human health as growing urban populations exacerbates the heating effect of climate change” (Harvey, 2020). If you ask me, it seems like something must be done to combat this on-going issue, but I’ll let you guys be the judge of that.
Over the past few centuries, highly populated and urbanized areas of the United States have been faced with increased temperatures as compared to non-urbanized areas, resulting in daytime temperatures that are, on average, 1-7℉ higher in major cities, especially in more humid regions of the U.S., like the East Coast (EPA, 2023). Through this process the term Urban Heat Island effect was coined during the late 19th century in hopes of bringing awareness to this process and starting to help combat it. However, with the rise of global warming and increased urbanization, many areas have had detrimental losses of vegetation and the implementation of more materials that make up sidewalks and pavements, which don’t absorb the heat but rather reflect it, creating elevated temperatures and leading to a more prevalent display of this process. Also, the loss of vegetation can create many more issues for rats, as it disrupts the ability to obtain natural sources of food, shading, and shelter.
So why worry about the rats you may ask? Well, taking a rat-infested city like Washington D.C. into account, the fourth most rat-infested city in America, according to an annual list of the Top 50 Rattiest Cities by the pest control company Orkin, one can only assume that this urban heating effect has drastic effects on the success and prevalence of these rodents (Orkin, 2022). However, you may be wondering what’s the harm, other than human effects, in displacing such animals and ultimately reducing the overall population in major cities? See that’s the controversial part, it all depends on who you ask. Personally, I tend to agree with scholars like Chelsea Himsworth, director for the Canadian Wildlife Health Cooperative, University of British Columbia, who believes that feelings towards rats should not be seen as negative but instead, “we need to recognize that the city is an ecosystem and that rats live here too” (Himsworth, 2019). While others like Gerard Brown, a man who has lived in Washington D.C. all his life, says “rodents cause property damage, chew on electrical wires that can start fires and can spread disease, although that is extremely rare in cities” (Chason, 2017). The reason that I agree with Himsworth’s stance is because I believe all animals should have an equal opportunity to thrive in an environment. We as humans should respect animals as we demand the same respect in return.
No matter what stance you take on the rat issue, it still important to gain understanding of how urban heating island effect is creating issues for the size of these animals. To do this however, one must know about Bergmann’s Rule, a rather simple concept that explains that animals in colder climates tend to be bigger in size, while in warmer climates it said that animals tend to be smaller. In the case of highly urbanized areas like Washington D.C., I know this rule may be hard to believe, as the size of the rats seem quite large, yet overtime, this rule might prove to be true. With increased temperatures from climate change and global warming, along with the increased display of the urban heat island, temperatures will continue to rise in cities compared to other places and the effects that are outlined in Bergmann’s Rule will become more prevalent. Unless of course, the urban heat island effect, might be showing the opposite effect?
While very confusing to understand from the surface, the urban heat island effect is caused by loss of vegetation and creates further issues with sustaining the remaining vegetation left. This requires rats to search outside of their natural diet, forcing them to examine other parts of the city which includes a lot of trash that is considered very unhealthy for a regular rat’s diet. Many researchers have tried to study this and have hypothesized “that the mammals are growing bigger because cities provide something of a TV-dinner-on-the-couch lifestyle: easy access to calorie-dense food, less need to scavenge, and fewer predators…” (Cohen, 2021).
This in turn, could severely impact the overall health of these rats and make them larger and more densely populated. In the scholarly article titled, “Urban heat island effect and rodent body condition”, researcher Brittany Allen investigates how the urban heat island effect is affecting rodents’ health and body conditions. Having captured 116 adult pocket mice and Merriam’s kangaroo rats around the Phoenix, Arizona area, Allen analyzed the bodily conditions of these rodents using accurate and noninvasive quantitative magnetic resonance. Allen looked at how the change in temperature from the urban heat island effect is creating differences in certain physical attributes such as storage of energy rich fat, survival, and reproduction when compared to areas that aren’t being affected by the urban heat island effect. The study found that the continuing negative ramifications were supported by the increased display of the urban heat island, and this in turn, could ultimately affect the survival of these rats especially in hotter seasons like Summer and Spring, reducing the overall sighting of rats in urban areas (Allen, 2021). Furthermore, increased temperatures can create issues for rats as it pertains to dehydration, which can result in a weakened immune system and a higher susceptibility to diseases. This not only creates health issues for rats, but pulls human into the equation, pushing for further need to help combat the effects of urban heat islands. Unless of course you just want a disease outbreak!
Behavior and Habitat changes is also something that has been put into question since the effects of urban heat islands has become more prevalent. City rats, specifically brown rats usually adapt to these urban environments wherever they can find an abundance of food. As a result of the urban heat island affect, there is a reduced availability for water in urban areas, which can force rats to seek out cooler areas, leading them to seek refuge underground in the sewers. This has led to numerous issues in major cities, and more specifically the Washington D.C. area. According to Beth Mole writer for the ars TECHNICA, “in a report released by the Centers for Disease Control and Prevention, DC health officials rate out the first two known cases of hantavirus spillover in the city” (Mole, 2022). Cases like these represents some of the possible effects of rats going into the sewers, which is growing in number as rats are seeking cooler areas because of increased temperatures. Also, urban heat island effects are disrupting the nocturnal patterns of city rats, but elevated nighttime temperatures are leading to increased sightings during the daytime as rats believe that its nighttime in some areas, ultimately increasing possible human encounters. This could explain why you see them a lot more during both daytime and nighttime hours, or at least I do.
Through you might find city rats to be quite disgusting or maybe even cute, there’s a point where you must realize that a problem is present. With increasing temperatures and the developing effects of urban heat islands, city rats are at risk for becoming increasingly malnourished and displaced from their current habitat. This in turn, is opening the door to several issues most of which could negatively impact humans. From great susceptibility to catching diseases, to denser population of rats in more urbanized areas, the time is now to start to try and combat this ongoing process before it becomes too late to reverse its affects. Not only that, but hopefully from hearing about these issues you begin to question how this process is affecting humans beyond just feeling the elevated heat. So, the next time you see a city rat scurrying in the street remember that, while they may be scary, they ultimately have to same goal in mind, to thrive in an ecosystem that that is inherently just as much theirs as it is ours.
Thanks for reading!
If you found this post to be informative or eyeopening check out some resources listed to see how the Urban Heat Island Effect is not just effecting rats but humans and other animals as well!
Resources:
Urban areas typically get much hotter than rural or natural areas. The higher temperatures in cities are caused by the presence of lots of b
An urban heat island, or UHI, is a metropolitan area that's a lot warmer than the rural areas surrounding it
References
Allen, D. B. (2021). Urban heat island effect and rodent body condition. ProQuest Dissertations & Theses Global. https://www.proquest.com/dissertations-theses/urban-heat-island-effect-rodent-body-condition/docview/2616611732/se-2
Chason, R. (2017, September 13). A downside to D.C.'s population growth? The growing number of rats. Washington Post. Retrieved October 8, 2023, from https://www.washingtonpost.com/local/dc-politics/a-downside-to-dcs-population-growth-the-growing-number-of-rats/2017/09/13/b17a68d2-93da-11e7-89fa-bb822a46da5b_story.html
Cohen, A. (2021, August 19). Nothing to see here. Just city rats getting bigger and bigger. Fast Company. Retrieved October 8, 2023, from https://www.fastcompany.com/90667459/nothing-to-see-here-just-city-rats-getting-bigger-and-bigger
EPA. (2023, August 28). Learn About Heat Islands | US EPA. Environmental Protection Agency. Retrieved October 8, 2023, from https://www.epa.gov/heatislands/learn-about-heat-islands
Harvey, C. (2019, November 21). Urban Heat Islands Mean Warming Will Be Worse in Cities. Scientific American. Retrieved October 8, 2023, from https://www.scientificamerican.com/article/urban-heat-islands-mean-warming-will-be-worse-in-cities/
Himsworth, C. (2019, July 10). Living with rats involves understanding the city as an ecosystem. The Conversation. Retrieved October 8, 2023, from https://theconversation.com/living-with-rats-involves-understanding-the-city-as-an-ecosystem-118383
Kullberg, A. T., & Feeley, K. J. (2023, February 14). Urban heat islands and what they can teach us about climate change. Frontiers for Young Minds. https://kids.frontiersin.org/articles/10.3389/frym.2023.943515
Mole , B. (2022, March 4). The rat problem in Washington, DC, is so bad, two people got hantavirus. Ars Technica. https://arstechnica.com/science/2022/03/the-rat-problem-in-washington-dc-is-so-bad-two-people-got-hantavirus/
Orkin. (2022, October 17). America’s 50 Most Rat-Infested Cities in 2022. Orkin. Retrieved October 8, 2023, from https://www.orkin.com/press-room/orkin-top-rattiest-cities-2022
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Urban heat island. Education. (n.d.). https://education.nationalgeographic.org/resource/urban-heat-island/#
YouTube. (2022). Cities on Fire: The Urban Heat Island Effect. YouTube. Retrieved December 6, 2023, from https://www.youtube.com/watch?v=ZNYGtdGbQDA.