Month: October 2024

Critical review of “The ecological impact of city lighting scenarios: exploring gap crossing thresholds for urban bats”

Posted on by Wesley Scott Wallace

https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.12884

As urbanization continues around the world wildlife are affected by a variety of artificial factors. Artificial lighting is a strong factor that affects nocturnal wildlife in urban areas. Bats in particular can be impacted by artificial lighting, as it may disrupt their movement and behavior. The common pipistrelle (Pipistrellus pipistrellus) is an urban dwelling bat commonly found in cities of the United Kingdom. Researchers in this study explored the relationship between pipistrelle movement between tree cover gaps and crossing distance and light intensity. 

Through stratified sampling in England’s West Midlands, gaps in urban tree cover were selected for surveying. These gaps varied in distance and lighting level and were surveyed using bat detectors and researchers who recorded their flight path. After surveying, logistic regression models were generated to identify minimum lighting levels required to create a barrier effect. These thresholds modelled as a function of crossing distance. The model was applied to Birmingham, England maps of tree cover and artificial lighting to create a model of landscape resistance to bat movement due to light. Future urban lighting scenarios were considered through these spatial models. The majority of pipistrelles crossed in the darker parts of the gaps indicating an aversion to light pollution. Light requirements to create a barrier reduced as crossing distances increased. 

A strength of this paper is the layout of the methods section. It is split into 5 distinct subsections that clearly describe the study. Each subsection is very thorough and explains the reasoning behind many of the team’s decisions. I think the location of the study was a good choice because it can be generalized across the UK, as many of the urban centers have similar structural layouts. The model can be applied to maps of different cities for further research. The study could have benefitted from a second city with a more rural landscape to compare the differences in bat cover gap usage. 

I think the potential lighting scenario models should have been further explored with a few more scenarios. They only looked at a Bright City and Dark City model in their analysis. If a moderately lit city model was included additional conclusions could have been drawn. Additional species could have been included as well to add more complexity to the results. The results section is very concise and clearly explains their findings. The discussion is quite thorough and does a good job of looking to the future. Further research can explore the dimming of artificial light sources during periods of high wildlife activity. Other nocturnal wildlife species should also be studied to assess their tolerance and reactions to artificial light.

Hale, J.D., Fairbrass, A.J., Matthews, T.J., Davies, G. and Sadler, J.P. (2015), The ecological impact of city lighting scenarios: exploring gap crossing thresholds for urban bats. Glob Change Biol, 21: 2467-2478. https://doi.org/10.1111/gcb.12884

A critical review of “Perceptions and attitudes to understand human-wildlife conflict in an urban landscape – A systematic review”

Posted on by Jackson Alexander Lemons

As the world becomes rapidly urbanized, wildlife habitats become more encroached upon, leading to greater wildlife colonization of urban habitats. This has led to a dramatic increase in human-wildlife conflicts (HWC), be it threats to human life, wildlife attacks on pets, vehicle collisions, or property damage. Attitudes and perceptions of people within urban areas directly impact how urban wildlife is managed; this highlights the importance of having a well-developed understanding of attitudes towards wildlife. The paper “Perceptions and Attitudes to Understand the human-wildlife Conflict in an Urban Landscape – A Systematic Review” explores that by reviewing many studies and drawing conclusions about the relationship between public opinion and wildlife management. 

The systematic review seeks to answer two questions: How were the perceptions or attitudes of urban residents used to understand urban HWC, and how does the inclusion of citizens’ perceptions or attitudes assist in reducing urban HWC? The authors utilized the PRISMA framework for their systematic review, which are academic standards and protocols to review large amounts of research articles that allow other researchers to reproduce their findings. It’s a transparent research methodology. The inclusion criteria of the paper can be summarized by the papers being relevant to the stated research question, the paper being published after the year 1999, the paper being written in English (which may be a limitation to the study, given its global applicability), the paper being peer-reviewed. The exclusion criteria of the paper can be summarized by relevance to public perception through questionnaires or surveys, non-wild species (such as domesticated animals), and studies conducted in rural areas or laboratory environments. Refer to Figure 1, a graphic representation of the PRISMA framework.

After the literature was screened, the data was extracted from them; several graphical representations were made to show the geographical distribution of the research and the frequency of keywords through word clouds. The country with the largest number of studies was the United States, with 43 research articles comprising 34.68% of the literature. Of that 43 articles, 52 species out of the 56 species mentioned in those papers were mammals and mainly predators (bears, grey wolves, coyotes, and cougars); this made me wonder if this was caused by the large controversy of reintroducing tertiary predators out west. If so, understanding public opinion in those communities would be important because it’s a divisive issue, with some communities being strongly opposed due to livestock predation, property damage, and generally posing a threat to human safety. On the other side of the debate, environmentalists strongly support the reintroduction of predators to restore ecological balance and control prey populations.

The takeaways the authors had for the reader were as follows. Frequent observations of wildlife boost tolerance levels among residents in urban areas, leading to more preference for less lethal wildlife management strategies to mitigate and control conflicts. A large limitation of the current literature on public perception and attitudes is that it fails to address more than one species on a longer time scale. There was a lack of longitudinal studies to study the changes in public perceptions, which should be a high priority among researchers given its impact on effective wildlife management. Addressing that research gap could provide valuable insights into how urban communities evolve in their understanding and acceptance of wildlife.

https://www.sciencedirect.com/science/article/pii/S1470160X23004612

Blog #2 Reptiles in danger: Implications of road mortality in wetlands of South America

Posted on by Kenia Barajas-Salazar

Link: Reptiles in danger: Implications of road mortality in wetlands of South America | Request PDF (researchgate.net)

The paper “Reptiles in danger: Implications of road mortality in wetlands of South America” does a great job at comparing different sites in the Parana River floodplain roads in relation to seasons, species diversity, abundance, and hotspots. There relationships of magnitude, timings, and locations were able to be pooled together through the researcher’s analysis of intrinsic (habitat use), extrinsic (temperature, precipitation, hydrometric levels) and anthropogenic factors (traffic volume) The visualization did a good job at illustrating the results, especially Fig.3 with relation to seasons and number of reptiles roadkill’s at the three sites. This helps to realize that there are so many factors that can be considered. Along with other papers the results bring more attention to placing more emphasis on conservation management to be geared on amphibians and reptiles that are the highest susceptible subjects to road mortality rates in wetlands. It was found that species richness had a significant increase as altitude decreases due to rising temperatures. Hence, the North region had higher richness of reptile species, but lowest abundance of reptile roadkill’s. The habit for this region consisted of the highest spatial heterogeneity of forest and wetland structure that aided in microhabitats for snakes.

This paper caught my attention due to the fact that it looks at road mortality specifically in relation to wetlands of South America. Since I work at an urban forest that has a wetland area with a wild population of different species of turtles. This paper calls to me because of the emphasis on higher vulnerability to reptiles due to thermoregulation and slow movement. Moreover, with the knowledge that each individual has their own home range while one goes out way farther some stay in their usual area. In the past year outside of my working area I have come across two turtles in the road that I have moved that would have otherwise been hit by another incoming car. Then, at my internship in Massachusetts one summer I would see so many turtles that would be moved off the roads. Hence, why this topic intrigues me and not just on turtles but also other species such as snakes that people especially don’t really care about swerving around.

I believe that the researchers could improve their data analysis of the environmental conditions’ variables. Such as providing more accurate precipitation readings by collecting days using Kestrels instead of just noting the average precipitation of the last three days. Moreover, there could have been more visits to the roads to include more data. It is stated that the data of GLMM showed that precipitation had no effect on reptile roadkill abundance. This raises an even higher concern that data could have been collected better for more accurate precipitation readings. This is due to the fact that it is widely known that reptiles often become more active after a precipitation event. These events could have been missed due to the short sampling period of taking the environmental condition measurements. However, it is a good point that the researchers did state that seasons were part of the additional variables which took part in the significant variations seen in the GLM abundance of reptile roadkill’s. It was found that Autumn had the highest species abundance compared to spring, winter, and summer. Additionally, spring has a higher number of roadkill’s compared to winter. This is important in creating modified mitigation strategies for each season that calls for different levels of risks to wildlife.

Other additional variables that should be considered are zones such as school, residentials, and industries, in relation to the differing speed limits to show if there is a correlation between the speed limits and roadkill. This could help in shifting conservation attention to zones that have lower or higher levels of speed limits to consider altering the levels for better visibility. Especially when overlapping with the sections North (NS), Centre (CS), and South (SS) of Parana River that were observed to have higher numbers of roadkill and compare those zones. I might have done a number of days for overall data collection differently in that increasing the field visits to have had the different regions of NS, CS, and SS meet the minimum number required for Autumn Optimized Hot Spot Analysis. This would have helped to have greater data on hotspots not just for region SS but for the others.

I appreciate how in the paper’s discussion two plausible reasons were given for how in the study a large proportion of reptile roadkill were snakes One that there is just a greater snake species richness in the area and second that people intentionally run over snakes. Additionally, how factors such as size of the snakes affect home range and movement frequencies when looking at factors such as foraging and being ectothermic animals. This builds onto the later elaboration on how pregnant snake females use the roads for thermoregulation which find themselves at higher risks of people just killing them by hand or by vehicles even in protected areas. This helps the readers to understand how even people’s perspectives on certain species a variable in species survivorship rates is also. Moreover, the highest world-wide threatened reptile species are those that live in freshwater environments that are not subject to negative effects from human activities. Future research directions are looking at study designs of roadkill’s in terms of reproductive seasons, exposure levels, and human population densities.

Effect of Human Activity and Presence on the Behavior of Long-Tailed Macaques (Macaca fascicularis) in an Urban Tourism Site in Kuala Selangor, Malaysia

Posted on by Karim Aguilar Ortega

In Malaysia, many of their cities have monkeys interacting with urban areas. Some individuals label monkeys as ‘pests’, due to their behavior. There has be an increase of complaints of urban monkeys, this causes management strategies to mainly reduce human populations that impact animals welfare/conservation. This study aims to see how human activity influences the ecological activity’s of the long-tailed macaque.

Methods

The research took place in Bukit Melawati and Kuala Selangor, which are both known to be a popular tourism site. The study site was divide into 3 zones, these zones included high/medium/low traffic sites. These sites were determined by interviews with residents and determined by team observations.

The research used instantaneous scan sampling for behavior sampling. LTM were observed daily from 9:00 to 17:00, individuals were recorded at specific time points at varying intervals (3 -11 minutes long). A total of 1761 scans were conducted across all time points. Behaviors were categorized into aggression, self-grooming, feeding natural, feeding unnatural, inactive, affiliative interaction, sexual, and travel. Researcher also recorded the type of structures the LTM occupied.

The research analyzed the data by bootstrapping, using a generalized linear model, and a percentage calculation.

Figure 1 – Study area

Results

From the results it was found that the LTM were observed to be traveling, inactive, interacting with other monkeys, and feeding naturally in 94% of the scans (figure 2). Of all of the unnatural feeding, only 10/6% were by humans. Out of all of the inactive LTMS, 54% were alert inactive.

Figure 2. – Activity of LTM

Observations were mostly during the early morning, followed by early evenings, late evenings, late morning, and afternoon. But these results are not a true representation of LTM present but the amount of time observed. Figure 3A shows the activity budget proportions of LTM

Figure 3 – Activity budget based on time of day, zone, weather, and presence of humans

Based on figure 3B, it showed that most LTM were observed in medium traffic areas. LTM had more time feeding in low traffic zones compared to the rest. Which can lead to to how human presence having an effect on the LTM. In figure 3D, it showed that LTM fed 9.9% of time in the presence of humans compared to 12.8% of the time.

Conclusions.

From the study it showed that LTM can be highly adaptive as they alter their behavior to survive in urban areas. The study also showed that human presence influences LTM behavior, as seen from figure 3. They potentially see humans as threat, due to their feeding being higher when they are not in the presence of humans. This study can help future conservation efforts with LTM.

Study Limitation

I believe one major study limitation of this study was not considering age/sex categories. I believe if this study used that kind of category it would of be very useful. It could possibly show variation of the LTM.

Another study limitation from the research is that it was too short. The study I believed should of been much longer. The study was over a 4 month long period, which doesn’t seem like a lot of time to study behavioral changes of a species.

Entezami, M., Mustaqqim, F., Morris, E., Lim, E. S. H., Prada, J. M., & Paramasivam, S. J. (2024). Effect of human activity and presence on the behavior of long-tailed macaques (Macaca fascicularis) in an urban tourism site in Kuala Selangor, Malaysia. Animals, 14(8), 1173. https://doi.org/10.3390/ani14081173

Predictable Features Attract Urban Coyotes to Residential Yards

Posted on by Jimmy Campbell

Overview

Urban coyote sightings are becoming more and more common and are eliciting attention from every direction. Coyotes will shift their hunting patterns if they commonly visit an urban area. They do so by becoming more nocturnal and coming out during times of the night that has less human activity. Urban carnivores, such as coyotes, are likely to visit residential yards for a multitude of reasons. One reason can be due to individual health. Urban wildlife have began associating humans with food, anthropogenic food that is, and this is causing an increase in human wildlife interactions/conflicts. A sick coyote is definitely more likely to search for an easy meal and urban residents often have just what the sick animal is looking for. When an animal is sick, they are said to have a greater acceptance of risk, which can explain why sick animals are more willing to approach objects that a healthy carnivore would be afraid of. Mange has been the most common disease that has been noted from previous studies in sick urban coyotes. Hypothesis for this study was that coyotes use residential yards that contain anthropogenic food sources but also contain cover to conceal them and can vary amongst their body condition. The study took place in Edmonton, Alberta, Canada. The coyotes were trapped using padded foothold traps. They were then collared and released. They created 7 landcover types and 4 land use categories to understand a coyotes habitat selection. They also decided to research the time of day that coyotes were entering these residential areas to understand the correlation between human activity and coyote activity.

Results

Healthy coyotes were 4 times more likely to avoid residential areas than sick coyotes even though all but 2 coyotes avoided urban settings. Coyotes tended to avoid residential areas more during the daytime hours than at night. Backyards with fences were 67% less likely to be selected by coyotes, 22% more likely to contain a food source, 3.3% of yards preferred had more cover and 1.3% had more fallen fruit. Diseased coyotes did tend to use residential areas more during the daytime hours than healthy coyotes. Sick coyotes were using anthropogenic housing more frequent then healthy coyotes. With these results, it led the researchers to believe that human-carnivore interactions are more likely to be caused by a sick animal trying to live an easier life than a healthy specimen.

Implications

This study can help explain many reasons one may be seeing an urban carnivore. Some key components to take away from this study is ensuring all trash is kept up and locked up, yards are fenced, bushes are trimmed, decks are sealed off and compost piles are not smelly or wide open. Some things that I think should be taken into consideration is the time of the year. Certain times of the year can change habits. In a time of the year where there is less natural food, you may be more willing to see an urban predator. During spring when young is born for all species, it is likely that there will be less activity seen in an urban environment. Also, location can play a big role in this. This study was only focused in one city in Canada. Different parts of North America can contain coyotes with different habits and mindsets. Chicago is notorious for having coyotes seen during the daytime. They have gotten used to people and there is loads of anthropogenic food sources there.

Source

M. H. Murray, C. C. St. Clair, Predictable features attract urban coyotes to residential yards. The Journal of Wildlife Management. 81, 593–600 (2017).

Critical Review of “mallard brood movements and survival in an urbanized landscape”

Posted on by Marley Kelly

Mallards must consider two stages of their hatchlings lives when picking a nest site: nesting, and brood rearing. Due to urban fragmentation, there may not be suitable brood rearing habitat close to chosen nesting habitat.

When habitat quality is poor, this may cause a trade off between habitat selection for nesting or rearing. This study observed brood/ducking survival, brood movements, home range size, and habitat composition to understand how urbanization affects nesting choice and duckling mortality.

The researchers identified nests in their study area (Connecticut) by searching for them at state-managed water bodies. They also recruited public reports of duck nests by use of press releases and social media. This allowed them to identify nests in secluded areas and in densely populated area like yards and public parks. I think this was a very clever method to get a variety of habitat types, involve the public, and gain permission to complete research on private property. Using different methods of nest identification is a good way to avoid bias. This shows how citizen science projects like iNaturalist could be used in tandem with more traditional methods to get more diverse results. After nests were identified, they regularly checked nest count and estimated incubation stage. They also attached GPS backpacks to the adult females during the last week of incubation. They checked the nest after the female had left for more than 12 hours to determine the fate of the eggs. They then found and regularly observed broods until it was determined that the brood was a survival success or failure.

The caption for this figure was slightly confusing, but I believe this is showing a single female’s path throughout nesting and rearing.

The results of this study showed that females can nest successfully in urban areas of Connecticut but experience greater duckling mortality. This could indicate a difficulty with finding or accessing suitable brood rearing habitat. Traveling distance did not affect brood success. Broods relied on wetlands for rearing and often traveled along streams to reach them. This shows the importance of protecting connections between nesting and rearing habitats, and the importance of protecting wetlands and providing adequate cover for young ducklings to avoid predation. This study was very thorough and I found the methods of data collection very interesting. Their use of multiple different methods including citizen science shows a different application that I had not previously considered.

Dykstra, L. R., M. T. Huang, and T. A. G. Rittenhouse. 2024. Mallard brood movements and survival in an urbanized landscape. Journal of Wildlife Management 88:e22578. https://doi.org/10.1002/jwmg.22578: Critical Review of “mallard brood movements and survival in an urbanized landscape”

A Critical Review: The Mental Health Benefits of Purposeful Activities in Public Green Spaces in Urban and Semi-Urban Neighborhoods

Posted on by Grace Elizabeth Agnello

Introduction

The overlap between mental health and green spaces is becoming a widely studied topic as urbanization increases and there are fewer green spaces. By 2050, 68% of the global population will live in cities. Living in cities can be associated with mental health stressors such as anxiety and depression, as well as physical health issues from air and noise pollution.

The research article I chose for this blog post is titled, “The Mental Health Benefits of Purposeful Activities in Public Green Spaces in Urban and Semi-Urban Neighbourhoods: A Mixed-Methods Pilot and Proof of Concept Study.”

Overview of the Study

In order to investigate if there are differential health and mental health benefits associated with activities in green spaces, three groups of volunteers at different conservation sites were selected and participated in group guided walks, practical conservation tasks, and citizen science. The conservation sites used in this study are managed by the Yorkshire Wildlife Trust, The Conservation Volunteers, and the Friends of St. Nicholas Fields in the United Kingdom. Walking, conservation, and citizen science were shown to be associated with improved mood. These outdoor activities were also shown to be purposeful and helpful in providing structure. The categories of action that led to improved mood include the following: Restorative exposure that reduces attention fatigue and distress, facilitating social interaction and enhancing social cohesion, facilitating and promoting physical activity, and filtering out the negative effects of noise, air and heat pollution. Results were collected through a self-reported well-being test, which was measured using the Short Warwick-Edinburgh Mental-Wellbeing Scale (SWEMWBS).

Figure 1. St. Nicks Nature Reserve, York

Improvements to the Study

I believe that this study would be more impactful if it focused on how people use green spaces in their own neighborhoods. It may be interesting to compare the mental and physical effects of green spaces in a neighborhood that has an abundance of them, versus a neighborhood with limited green spaces. This could also lead to more research about how to better implement green spaces in urban areas and how they are best used.

One other limitation that was explicitly mentioned in the article was that all of the study participants are existing volunteers for conservation and wildlife groups. I believe that this can lead to bias, because people who volunteer for a conservation group are more likely to enjoy green spaces and outdoor activities.

Significance of the Study

As discussed in this research article, the combination of long-term physical conditions with depression is associated with the greatest decrease in quality of life. It is important to reconsider how we can use the outdoors to improve the physical and mental health of people living in cities. As more people move to cities, the issue of accessibility will become more prevalent, and it will be important to have research that investigates these positive outcomes in order to make policy changes.

Source:

Coventry, P. A., Neale, C., Dyke, A., Pateman, R., & Cinderby, S. (2019). The Mental Health Benefits of Purposeful Activities in Public Green Spaces in Urban and Semi-Urban Neighbourhoods: A Mixed-Methods Pilot and Proof of Concept Study. International journal of environmental research and public health, 16(15), 2712. https://doi.org/10.3390/ijerph16152712

Predicting the fate of urban species

Posted on by Michely Reis Coimbra

 Beyond the scope of ecosystem services, urban species are of great importance for their cultural, economic, and intrinsic values. As global climate changes we often come across research trying to predict how species will react to our changing world. But what of urban species? How will they be affected? 

 This paper looked over terrestrial species distributed in over 60 cities across developed urban cities in Canada and the United States. Using the Global Information Facility (GBIF) they focused on common urban species and species with at least 10 recorded sightings in the last 10 years. For predicting future climate conditions, they used global circulation models in R that consider different levels of greenhouse gas emissions and predicts the increase in urbanization under different conditions of urban sprawl and densification.

The results of this analysis predicted that, by the end of the century, all of these cities will experience gain and losses of species. Greenhouse emissions and urbanization will make species’ turnover more dramatic, and it will influence which species will do well in urban areas.  For instance, places with colder and wetter climates, such as in Canada and the Midwest will see the largest influx of new species. Meanwhile hotter places with a lot of rainfall, such as the subtropical U.S. and Coastal California will lose many species. Arid places will see the least number of changes since they are more resilient to climate variations.

What caught my attention in this paper is that according to their predictions, biodiversity as we know in urban areas could change a lot. For instance, urban areas will probably sound quite different from now, as some species of birds leave, and new species move in. We may also experience more exotic species in urban areas, which will increase competition for the natives already dealing with the pressures of an urban environment. Raleigh was one of the cities in this study, which is predicted to lose at least 32% of bee species.

As we continue to expand into urban areas, predicting the future might paint us a gloomy picture. The wildlife that we have grown used to seeing in our cities could be replaced by species more suited to our new climate reality. Which makes me question not only the ecological issues, but also how will this shift impact the way we connect with nature in urban environments, specially the ones that are part of our cultural identity. Gloomy as they might be, these predictions are critical, as they can help us to find solutions to reshape our cities in a way that minimizes the impact on the wildlife that shares urban spaces with us.

Source: Filazzola A, Johnson MTJ, Barrett K, Hayes S, Shrestha N, Timms L, et al. (2024) The great urban shift: Climate change is predicted to drive mass species turnover in cities. PLoS ONE 19(3): e0299217. https://doi.org/10.1371/journal.pone.0299217

College Squirrels gone wild? Using Sciurus carolinensis behavior to assess the ecosystem value of urban green spaces

Posted on by Haley Clayborne

Kay, A.D., Hughes, Mnew .T., Ammend, M.G. et al. College squirrels gone wild? Using Sciurus carolinensis behavior to assess the ecosystem value of urban green spaces. Urban Ecosyst 26, 81–88 (2023). https://doi.org/10.1007/s11252-022-01288-7

As urbanization becomes a more widepsread among cities across the globe, there have been many new solutions created as a way to help improve biodiversity in these areas with high amounts of urbanization. One of these is solutions is the implementation of “green infrastrcuture”. This study was done in Minnesota and included three different survery sites: college campuses, resedential yards, and municipal parks. The purpose of this study was to look at the giving up density (GUD) of the eastern gray squirrel in association to the green infrastructure. They also looked at the proximity of the green infrastrcture to roads and if this had any influence of the GUD of the eastern gray squirrels.

The study sites included nine different universities, seven municpal parks and 48 residential homes in the St. Paul and Minneapolis areas of Minnesota. In the second part of the study they assessed the effect of road proximity of on the squirrels GUD for only one of the college campuses (University of St. Paul). In each site they placed aluminum trays with sunflower seeds out for the squirrels. For each site they would place one tray closer in proximity to a roadway and one tray farther away from a roadway. They estimated the “maximum distance from road” using GoogleMaps and ImageJ software. For part 2 of the study they estimated the traffic volume on the University of St. Thomas Campus and explicitly placed the trays along the roadways.

Using the tray data, they found that the GUD did not differ among the three sites, but did differ due to the proximity to roads. The trays away from roads were visited more frequently than the trays near roads at all three locations. Greater distance to roads and the high traffic volumes are both linked to higher GUD. The maximum distance from roads varied at each site and location type, but was shorter for resedential yards in comparison to college campuses and parks. These results indicate that compared the residential yards, both parks and college campuses may be associate with reduced foraging costs for eastern gray squirrels due to greenspaces and distance from roads.

I think this study did a good job of placing feeding trays at several sites within the study site location. They did a good job of spacing the trays amongst each site in reference to roadways. One thing I wish this study did different was look at more than one unviersity setting for part two of their data. They only used one university to assess the direct impact of road proximity on the squirrels. If they had done more than one unviersity there could have been more data to compare these effects. Overall I think this paper sets up a good basis for the understanding on greenspaces in urban areas and college campuses and how roadways can have impacts on eastern gray squirrels foraging behaviors.

Urban Gray Squirrels

Posted on by Erik Bailey Williams

Urbanization is an obvious problem for multiple species of wildlife. Dependency on humans, and boldness are two of the largest effects urbanization has on species. One species in particular being the Eastern Gray Squirrel. From eating bird feed from backyards, to eating out of people’s hands, it shows that they have shifted from their natural avoidance of humans. A study conducted in Boston Commons, a 50 acre urban park in downtown Boston, shows this perfectly.

The study conducted on the boldness of the Eastern Gray Squirrel divides Boston Commons into 5 sectors, two of which had dense tree cover, while the others contained mostly grassland and scattered trees. All quadrants are surrounded by roadway, so noise pollution and distractions could be factors in results. The experimenter in the study observed squirrels in each quadrant 3 times for periods of 20-60 minutes throughout the month of March. It is important to note that this is around spring breeding times for squirrels, and could see increased activity and boldness. The experimenter observed squirrels feeding, how quickly the squirrels fled, how bold they were, or if they were conducting other activities. 

It is important to understand that this study has many flaws. One being that it is only a regional study, in a park setting. Boston has vastly different weather conditions in March than in say the Midwest. Only being a regional study, it can be hard to determine if the behavior in that specific region can correlate to different environments. Not only that, it is important to realize that another flaw in the sampling is that the study is at a time of peak activity, and no other time of the year. Squirrels breed and produce young between February and May. What if another study was conducted in July, when temperatures peak? Lack of consistency is also important to consider. A human body was introduced when seeing how bold the squirrels would be when presented with a nut in a hand. Some squirrels took it, and some didn’t. Humans aren’t perfect, and there is no control group in the study.

Overall the study does a great job of highlighting the problems of urbanization for squirrels. In the wilderness, a squirrel will not just walk up to an out of place object, a human, and accept a nut from their hand. It is just not realistic in their natural environment. An urban squirrel taking a nut from hand not only shows they don’t fear natural predators anymore, but they may be becoming dependent. No study is without flaw, and I think this could be a great resource in future research, to help raise awareness about problems of species urbanization.

Responses of urban gray squirrels (Scurius carolinensis) to humans and conspecifics in an area of Boston Common