Course:CONS200/2023WT1/Ecology & Management of Racoons in Urban Settings

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Introduction

An zoomed out image of a raccoon looking at you.
Image of a raccoon, zoomed out.

Raccoons are identified as invasive species, particularly when they are introduced to non-native environments such as Japan, where they pose a significant threat to indigenous biodiversity[1]. Furthermore, raccoons jeopardize native ecosystems by causing damage; for instance, in Japan, raccoons prey on Japanese crayfish (Cambaroides japonicus)[1]. This results in economic losses in agriculture, property damage, and the spread of disease[1]. Similarly, there are issues with human and raccoon populations occurring globally, with raccoons being characterized as nuisance animals or pests in urban and suburban settings[2]. Consequently, effective management strategies are imperative to protect biodiversity and ecosystems from the negative impacts of raccoons as invasive species, while also taking into consideration the ethical and moral responsibility[1].  

Background Information & History

A close up image of a raccoon looking at you
Image of a raccoon's distinct face.

Raccoons (Procyon lotor), native to North America, are mid-sized mammals recognized by their distinctive ‘black mask,’ ringed tail, and various fur colours, from black to white[3]. They possess dexterous front paws enabling them to  grasp food and they walk with flared toes on their hind feet, similar to humans[3]. They weigh 5-12 kg and gain weight in the winter to survive, as they do not hibernate[3]. Behaviour-wise, raccoons form flexible social groups changing size with their environment, known as fission-fusion societies[3]. They are primarily active at night (nocturnal) and during dawn and dusk (crepuscular)[3].

A map displaying raccoon range: from Canada’s southern half to Northern Panama and parts of Europe, including Germany and France.
Raccoon Range Map

Raccoons are highly adaptable, occupying habitats with water, food, and shelter sources, including burrows, hollow trees, and urban settings like sewers and garages[3]. Their habitat spans from Canada’s southern half to Northern Panama and parts of Europe, notably Germany and France, where they have become invasive[3]. As opportunistic omnivores, raccoons consume a wide variety of plant and animal food sources[3]. Raccoons breed from February to June, with babies (kits) born usually in May. Kits depend on their mother for two months before starting to hunt and forage. Raccoons have a life expectancy of 3-5 years in the wild and up to 21 years in captivity. Raccoons are considered pests due to their foraging behaviour, which can lead to damage to crops and other nuisances[3]. Raccoons occupying urbanized areas alongside humans date back to before the 20th century, leading them to become one of the most common omnivores or, to some, pests in North America[4].

Raccoon Behaviour Within Urban Areas

Image of a raccoon sitting in a garbage bin.
Image of a raccoon rummaging around a dumpster.

In cemented, urban environments where vegetation is scarce and human activity is at its peak, raccoons and other omnivorous animals, although facing numerous challenges, have been able to adapt their way of living to fit the busy environment[5]. When it comes to their denning arrangements, raccoons tend to prefer hollow trees but, in urban settings, are usually attracted to parks where they are able to avoid busy roads and buildings most often occupied by humans while also gaining access to possible food sources such as garbage cans available to raid in hopes of finding something to eat[5]. In many cases, raccoons are attracted to other denning sites as well including wooded areas, forest parkland, or sewers, residential areas, and other forms of man-made structures appropriate for their lodgings[2]. However, raccoons do tend to avoid highly-populated, industrial areas such as railways, streets, subway lines, high-density housing, and other commercial landscapes[2],

In relation to their diet, raccoons in urbanized areas tend to ingest non-food items alongside anthropogenic food found by scavenging through garbage cans, litter, etc.[5]. A study done in North Carolina on the behaviour of raccoons showed that raccoons living in human-dominated areas showed greater amounts of inedible items in their digestive systems than those living in less human-dominated areas[6]. However, it also showed that the overall condition of raccoons living in these human-dominated areas was proven to be better than those not, expressing a positive association between living closer to human activity and nutrition, although they lacked prey diversity[6].

Spread of Disease by Raccoons

Raccoons are recognized for their role in spreading diseases in urban areas, with specific types varying based on location. For instance, urban raccoons in Costa Rica, engaging frequently with people, have been identified as transmitters of numerous salmonella strains within their populations[7]. This transmission has also resulted in an escalation of antibiotic resistance, with strains exhibiting resistance levels ranging between 7 and 9% to certain medicines[7]. Disease stands out as a significant contributor to urban raccoon mortality, constituting an average of 50% of deaths in urban areas compared to only 19% in rural settings[8]. The elevated raccoon population density and the presence of disease-rich anthropogenic food sources contribute to this disparity. In various urban environments, wildlife faces exposure to antimicrobial-resistant bacteria (ARB) due to spatial overlap with domestic animals, as observed with Escherichia coli (E. coli), prevalent in 56.9% of urban raccoons[9]. Recognizing the potential public health implications and the imperative for effective raccoon management in urban settings, strategies like segregation and habitat modification emerge as crucial tools in mitigating the risks associated with disease transmission while simultaneously fostering coexistence between humans and raccoons.

Effect on Crops, Pets, and Private Property

The interactions between raccoons and the areas they inhabit provoke many challenges. In North America, where raccoons are a native species, agricultural loss is a leading issue; The deterioration of corn fields has become more common with an increase in the raccoon population[10]. This damage arises from raccoons feasting on crops, specifically sweet corn in both private gardens and agricultural areas[11]. Not only are there concerns regarding agricultural damage, raccoons have also posed a significant threat to property damage and pet health. Raccoons have proved to be “capable of exploiting urban landscapes”[12] by using human structures such as residential buildings for dens, which in turn causes great structural damage to homes[12]. Additionally, raccoons carry diseases that can be spread to domestic pets[3]. Some of these diseases include canine distemper, feline distemper and rabies[3]. In Japan, where raccoons are an invasive species, damage to native biodiversity is a significant threat[1]. The rapid spread of these creatures catalyzes the displacement and destruction of native flora and fauna causing stress to local ecosystems[1]. In both invasive and non-invasive cases, the challenges posed by raccoons extend beyond mere population control, encompassing profound ecological and economic ramifications. These findings underscore the complex interplay between raccoons and their environments, emphasizing the need for region-specific management strategies that consider the unique factors contributing to the invasive nature of raccoon populations. As efforts are made to address the impact of raccoons on agriculture, pets, and private property, it becomes imperative to adopt comprehensive approaches that balance effective population control with the preservation of local ecosystems and agricultural sustainability.

Habitat: Densities in Landscape

An image of a raccoon in a trash can.
Image of a raccoon rummaging through a trash can.
an image of a raccoon on house porch eating food.
Image of raccoon on a porch.

Through habitat fragmentation and the presence of humans, urbanization influences wildlife species including raccoons [13]. Raccoons inhibit both urban, suburban, and rural settings, with the highest density recorded in urban settings[2]. Urban sites that are correlated with human activity are the most commonly chosen habitat for raccoons, as it is a habitat that is associated with food[13]. In urban settings, raccoons commonly reside in wooded areas, forest parkland, and residential areas[2]. Data from a study conducted on raccoons in areas of northeastern Illinois, USA, presents evidence that increased survival, higher annual recruitment, and increased site fidelity are some of the factors that contribute to the high density of raccoon populations in urban settings[2]. Continuous control measures are needed in order to manage raccoon numbers in urban settings, due to their ability to quickly repopulate areas[2]. It is suggested that the most effective management approach is to reduce anthropogenic food sources that support the survival of raccoons at high densities[2]. Since better physical condition and higher rates of reproduction in raccoons are correlated with anthropogenic food sources and their abundance in urban settings[2].

Raccoons found in urban settings have fewer mortality sources than those found in rural settings[2]. The greatest cause of mortality for urban raccoons is disease and for suburban and rural raccoons it is vehicle-related[2]. Furthermore, nuisance-related morality is also taken into consideration for urban raccoons that live in close proximity to humans, as a result of them being euthanized[2].

Abundant raccoon populations in urban settings commonly lead to nuisance problems, with raccoons being the primary nuisance animal in urban and suburban areas as named by over 40% of North American animal damage control[2]. Additionally, an increase the threat of parasites and diseases is warranted with dense raccoon populations that are in close proximity to dense human populations[2]. Hence, the management of raccoon populations is often sought for.  

Management Strategies

Managing raccoon populations in the urban realm can prove challenging due to the adaptable nature of these animals[2]. Current widespread management strategies include:

Trapping and Relocation

An image of multiple raccoons that have been trapped in a cage.
Image of raccoon's in a trap.

Placing camera traps provides information on the present status of raccoons in a particular area, including the number or individuals, density and distribution[1]. In one management study, camera traps and bait traps were placed throughout a city, allowing to assess and approximate the distribution of raccoons and implement trapping accordingly[1]. The method for trapping raccoons has its advantages and disadvantages, while bait traps are an inexpensive method, they are less effective in areas with abundant bait resources[1]. This is a useful management strategy for places with a low budget and where staff have little specialized knowledge[1]. There are ethical concerns associated with relocation due to the stress on animals and potential territorial disputes that may arise[1].

Control Programs

Invasive species that become established can be managed through sustained control programs or eradicated[1]. Control programs such as the government-led Invasive Alien Species (IAS) are in place to monitor the effectiveness in reducing invasive species like pests, but they do not measure outcomes like whether biodiversity has increased or not[1]. Such programs have been implemented and evaluated in countries including Australia and New Zealand[1]. However, the planning and implementation of IAS programs that are well-designed and well-monitored proves to be a global challenge[1]. In Japan, there is an IAS designated for raccoons which resulted in raccoon management programs according to the Japanese Invasive Alien Species Act[1]. In charge of these control programs were local municipalities that controlled cities, towns, and villages[1]. Studies previously showed the effectiveness of managing raccoons by intensive control in the early invasion stage[1]. Yet, in the case of Japan few regions effectively managed to control raccoons and nowhere in Japan did they manage to eradicate raccoons[1].

Deterrents & Repellants

Image of an ultrasonic animal repeller.

Repellents are often used as non-lethal approach to combatting the impacts of other wildlife on human life[14]. Anthraquinone, a useful avian repellant was studied on raccoons as a form of mammalian repellent and it proved itself useful.[14] An anthraquinone-based repellant at 2% concentration increased feeding repellency to 71% compared to a 0.5-1.5% concentration resulting in a 26-37% feeding repellency[14]. Other forms of deterrent are electronic light and audio repellents, as for raccoons, they are the responsive to visual and audible stimuli[15]. Floodlights, strobe lights, lanterns, flares can all be used as visual stimuli to repel raccoons away from property, garbage, etc.[15].

Segregation & Habitat Modification

Segregation involves designing physical spaces or barriers that discourage raccoons from accessing them. Some examples of this include securing garbage bins and providing enclosed food boxes at parks. Furthermore, Habitat modification includes altering specific parts of the urban environment to make it less appealing to raccoons by removing items that could be used as food and shelter. Raccoons thrive in human-modified environments, and human activities have great impacts on raccoon body mass and behaviour[16]. This highlights the interconnected nature of urban ecosystems and the importance of recognizing wildlife in urban planning and management. Incorporating segregation and modification strategies into cities requires community involvement and municipal initiatives to ensure their success. Public awareness can play a key role in encouraging responsible waste management[17]. While segregation and habitat modification can reduce negative encounters between raccoons and humans, ethical implications are involved, as altering urban landscapes even more reduces the habitat area for wildlife. Balancing the needs of wildlife and human considerations requires thoughtful planning and management to achieve sustainable solutions.

Euthanasia

The euthanasia of raccoons as a management strategy in urban areas is a contentious practice with many ethical considerations to consider. Many argue that there are more humane ways to deal with raccoon-related issues, such as relocation, control programs, and non-lethal deterrence[18]. In a case in Alabama, online petitions protesting wildlife euthanasia, including urban raccoons, were signed by over 7,000 concerned citizens[18]. Public attention of this magnitude raises awareness of many questions about the balance between wildlife and human life in urban areas, especially as urbanization continues to expand. However, those in favour of euthanasia argue that these solutions do not suffice. For example, relocated raccoons in Ladysmith killed a farmer’s chicken flock, highlighting the downsides of certain practices[19]. Those in support of this practice argue that this is the most effective way to curb raccoon population growth and reduce their impacts on urban areas, such as waste, disease spread, and property damage[19]. Differing opinions on polarizing topics such as raccoon euthanasia bring a multitude of issues to light, especially regarding problems with existing solutions.

Public Awareness

Promoting public awareness of raccoons, their habitats, and their behaviour is a valuable and multifaceted management strategy that emphasizes coexistence with wildlife[20]. In the case of urban raccoons, this awareness can extend beyond general information to include specific considerations such as the diseases they can spread and prevention techniques on private property. One illustrative study by researchers from the Texas A&M University[21] emphasizes the need for citizens to be aware of zoonotic parasites carried by raccoons, shedding light on the potential health risks associated with these urban-dwelling mammals[21]. By educating people about these risks, members of affected communities can take preventative measures, such as vaccinations for themselves and their pets, contributing to the overall public health agenda. Furthermore, shaping public attitudes towards raccoons to minimize unnecessary fear and reduce irresponsible behaviour can have positive ripple effects on human-wildlife relationships in cities[20]. Well-informed citizens within urban areas not only foster a safer environment but also allow the public to participate more actively in urban raccoon management strategies that balance public health considerations and the well-being of wildlife.

Reduce Anthropogenic Food Sources

An image of a raccoon looking through a garbage can, presumably for food.

One of the most prominent factors contributing to the increasingly dense population of raccoons in urban and suburban areas is directly correlated to their access to food, specifically anthropogenic food left in garbage or other forms of waste[2]. Taking this into account, removal or limiting access raccoons have to any anthropogenic food and therefore cutting off their resources to live will ultimately decrease the raccoon population in that specific area[2]. This can be carried out through a multitude of ways such as covering waste containers, removing waste from waste containers before raccoons active hours, locking possible food sources (garbage bins, dumpsters, etc.) away properly and in a way that they are unable to claw/break through[2]. By restricting their access to anthropogenic food sources removes one of the most attractive part of human-dominated areas for raccoons, driving them out into more rural areas where alternative food sources become available[2].

Conclusion

Raccoons, characterized as both invasive and non-invasive[3] in various parts of the globe, have induced significant challenges to the urban settings upon which they reside. As raccoon populations and urbanization continue to increase[2], these issues will persist without sustained management strategies and public awareness on the subject[20]. Through examining the behaviours, habitats and effects of raccoon populations, a greater understanding of the conflicts and alliances with these creatures can be reached. With the adoption of different management strategies to keep these pests controlled, communities will be able to coexist with raccoons in the urban landscapes.

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 Suzuki, Takaaki; Ikeda, Tohru (December 2020). "Invasive raccoon management systems and challenges in regions with active control". BMC ecology. 20 (1).
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 2.19 Prange, Suzanne; Ghert, Stanley. D.; Wiggers, Ernie. p. (April 2003). "Demographic Factors Contributing to High Raccoon Densities in Urban Landscapes". The Journal of Wildlife Management. 67 (2): 324–333 – via JSTOR.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 Churcher, C.S.; Rossit, Tina-Louise (March 2012). "Raccoon". The Canadian Encyclopedia. Retrieved December 12, 2023.
  4. ↑ Fleming, P. A.; Batemen, P. W. (May 2012). "Big city life: carnivores in urban environments". Journal of Zoology. 287 (1): 1–23 – via Zoological Society of London.
  5. ↑ 5.0 5.1 5.2 Fleming, P. A.; Batemen, P. W. (May 2012). "Big city life: carnivores in urban environments". Journal of Zoology. 287 (1): 1–23 – via Zoological Society of London.
  6. ↑ 6.0 6.1 Parsons, Arielle Waldstein; Simons, Theodore R.; O'Connell, Allan F.; Stoskopf, Michael K. (October, 2012). "Demographics, diet, movements, and survival of an isolated, unmanaged raccoon Procyon lotor (Procyonidae, Carnivora) population on the Outer Banks of North Carolina". Mammalia – via De Gruyter. Check date values in: |date= (help)
  7. ↑ 7.0 7.1 Baldi, Mario (2019). "Salmonellosis detection and evidence of antibiotic resistance in an urban raccoon population in a highly populated area, Costa Rica".
  8. ↑ Bateman, PW. "Big city life: carnivores in urban environments". Journal of Zoology. 287.
  9. ↑ Worsley-Tonks, Katherine (2021). "Comparison of Antimicrobial-Resistant Escherichia coli Isolates from Urban Raccoons and Domestic Dogs". Applied and Environmental Microbiology. 87.
  10. ↑ Beasley, James (February 13, 2017). "Relationship Between Raccoon Abundance and Crop Damage". Human-Wildlife Interactions. 2.
  11. ↑ Conover, Michael (Summer 1987). "Reducing Raccoon and Bird Damage to Small Corn Plots". Wildlife Society Bulletin. 15: 268–272 – via JSTOR.
  12. ↑ 12.0 12.1 Gross, Justin (November 23, 2011). "Raccoon use of the urban matrix in the Baltimore Metropolitan Area, Maryland". Urban Ecosystems. 15: 667–682 – via Springer Link.
  13. ↑ 13.0 13.1 Bozek, Clarke. K.; Prange, Suzanne; Gehrt, Stanley. D. (December 2007). "The influence of anthropogenic resources on multi-scale habitat selection by raccoons". Urban Ecosyst. 10 (4): 413–425.
  14. ↑ 14.0 14.1 14.2 Johnson, Shylo R.; Deliberto, Shelagh T.; Urcheck, Kathleen; Gilbert, Amy T.; Werner, Scott J. (June 2022). "Concentration-response of an anthraquinone-based repellent for raccoons (Procyon lotor)". Applied Animal Behaviour Science. Vol. 251 – via Elsevier Science Direct.
  15. ↑ 15.0 15.1 Koehler, Ann E.; Marsh, Rex E.; Salmon, Terrell P. (March 1990). "FRIGHTENING METHODS AND DEVICES/STIMULI TO PREVENT MAMMAL DAMAGE-- A REVIEW". Vertebrate Pest Conference Proceedings collection.
  16. ↑ Turgeon, Geneviève (March 2, 2015). "Born to be wild? Response of an urban exploiter to human-modified environment and fluctuating weather conditions". Canadian Journal of Zoology – via Canadian Science Publishing.
  17. ↑ Corman, Lauren (2011). "Getting Their Hands Dirty: Raccoons, Freegans, and Urban "Trash"" (PDF). Journal for Critical Animal Studies. 9.
  18. ↑ 18.0 18.1 Burkett, Seth (September 16, 2013). "Petition seeks to end euthanizations". Decatur Daily.
  19. ↑ 19.0 19.1 Spence, C. (September 14, 2015). "Relocated raccoons kill pet chicken flock". Today in BC.
  20. ↑ 20.0 20.1 20.2 Basak, Sayantani (August 15, 2022). "Public perceptions and attitudes toward urban wildlife encounters – A decade of change". Science of The Total Environment. 834 – via Science Direct.
  21. ↑ 21.0 21.1 Ogdee, Jacob (2016). "Lack of human awareness and the need for increased public education regarding the zoonotic parasite, Baylisascaris procyonis". Human-Wildlife Interaction. 10.


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