Introduction
Population distribution and gene flow depends heavily on habitat connectivity. Fragmentation of natural areas causes genetic differentiation in urban landscapes. The consequences of fragmentation depends on the species; generalist species (wild boars) adapt better to artificialisation by exploiting resources available around smaller fragments. Wild boars prefer environments with dense vegetation, which provides them both shelter and food. The mobility and use of space of wild boars reflects their decisions balancing the benefits of exploiting a resource and the dangers it takes to reach them. Human disturbance here is the real danger. Human disturbance and habitat fragmentation leads to higher mobility and higher nocturnality. SDM (Species distribution models) are powerful tools to identify the distribution area of a species. These models generate statistical relationships between the probability of presence between species and environmental variables, such as land use, landscape metric, climate or topography. Using survey data this method can predict the ranges of species based on current or future environmental factors. This method was used in this study predict urban boar’s range and assess landscape features selected or avoided by this species. The first hypothesis being that wild boar’s presence in urban areas is determined by access of resources and modulated by avoiding densely built up areas. The second hypothesis is that Bordeaux’s urbanistic green frame is suitable for wild boars.
Methods
This study took place in Bordeaux Metropolis (southwest France). The study area was divided into 100-hectares cells, equaling 524 observation units. A third of these units (174) were randomly selected and explored from 25th March to 10th May 2019 to detect wild boar presence. Observations included sightings, rooting sites, wallows and trails. Other clues like footprints, rubs, hairs, or beds confirmed wild boar frequent the area. Cells where boars were present in were given an observation score of 1 (corresponding to a 100% probability that animals have been there) and the cell assigned 0 corresponded to absence of species. Then the probability of wild boar’s presence in each grid cell was studied using logistic regression models (R 4.03 software and QGIS) incorporating several predictor variables. These environmental variables included 1) physical obstacles to animal movements; 2) degree of human impact; 3) availability and accessibility of resources (food, water and shelter).The Garonne river and Bordeaux’s ring road were also seen as physical obstacles for the wild boar. Therefore, every grid cell was labeled based on its position to the river and its centrality to the road ring. The density of buildings was and roads was calculated in each grid cell and a French topographic database was implemented for metric precision. Hosting potential of a grid by a wild boar was estimated by calculating the surface area of lands that tend to provide resources and by assessing the level of fragmentation of forest habitats included in the cell. Overall by categorizing grid cells in three categories on level of amount refuge and food it was determined that 53.6% of the total study area had either refuge or food if not both. After removing correlated variables, they tested multiple model combinations and selected the best fit using AIC, BIC, and TSS metrics. The strongest model (TSS = 0.79) showed that wild boar presence increased with larger green areas (WBGF) and decreased with higher building density, confirming that access to resources and avoidance of dense urban zones best explained their distribution. Predicted probabilities were mapped to identify areas with high (>50%) or low (≤50%) likelihood of wild boar presence. Results showed that nearly 90% of the urban green frame was suitable for wild boars, especially outside the ring road and on the right bank of the Garonne River. A year-long camera trap survey beneath the ring road recorded 114 wild boars, confirming that animals use this underpass as a corridor between suburban and inner-city green spaces, validating the spatial model’s predictions about connectivity.

Results
Model analyses showed that wild boar presence in Bordeaux was mainly driven by the availability of green habitats and limited by building density. The best logistic model confirmed that wild boars were most likely to occur in areas with extensive wild boar green frame (WBGF) and fewer urban structures, especially outside the ring road and on the right bank of the Garonne River. Overall, 68.9% of grid cells had a predicted boar presence probability above 0.5, closely matching field data where presence was observed in 67.8% of surveyed cells. Nearly 90% of the green frame showed a high probability of use. Inside the ring road, boars were mostly present on the right bank (70.5% of green area likely occupied) but rare on the left bank (22%). Camera trap data supported these predictions, showing frequent use of an underpass beneath the ring road, with boars moving both into and out of the city. This confirmed that while boars prefer peripheral green zones, they can cross barriers and access central urban areas through existing corridors.
Critique
The study was successful in using statistical modeling intertwined with field observations to understand urban wildlife niches. The author’s use of statistical models like SDMs and QGIS and R provided a thorough, clear, and replicable method for assessing environmental variables. Overall the variety in methods like field observations, camera monitoring, and spatial analysis makes the research highly reliable. However, there were some limitations to the study. For one, the field survey took place over a short period of time during a single season (spring). This small temporal scope may not capture the variation in boar behavior across seasons. Additionally, using whole 100-hectare grid cells may miss fine-scale behavioral patterns and small habitat use within fragmented areas. Furthermore, the cells with no seen boar behaviour within were marked as “absent”. This is tricky, because assuming absence of evidence is one thing , but this does not give us the right to assume actual absence of the presence of boars in that grid. Lastly, it would’ve been beneficial to include social attitudes to implement in the coexistence between boars and humans. All in all, the paper provides valuable knowledge about how generalist species exploit urban environments and how we must acknowledge the coexistence of these species and us.

Invasive Species in Penguin Worlds:

An Ethical Taxonomy of Killing for Conservation

Within this study, Van Dooren (2011) evaluates numerous different conservation strategies used on an endangered population of small penguins (Eudyptula minor) living in Sydney’s North Harbour, to explore which types of intervention, both human and non-human, are acceptable, and assess the ways in which we justify these interventions. Van Dooren (2011) explores many of the reasons that the term “invasive” has been deemed so problematic. Specifically, this article focuses on investigating much of the conservation legislation and practice within New South Wales, and the somewhat unusual methods that are employed to classify these various organisms. This article highlights the need to reconsider current invasive species management strategies, as opposed to being innately attracted to the “easiest” solution, instead prompting open and inclusive conversations about the goals, values, and priorities of all parties involved to create more multifaceted management solutions.  

Van Dooren (2011) explores various attempts to manage predation threats to an endangered population of little penguins (Eudyptula minor) living in Sydney’s North Harbour. Van Dooren (2011) begins by introducing the first threat to the small penguins, in the form of the exotic red fox (Vulpes vulpes). The solution offered for this species of concern was total eradication through baited poison traps. This practice was conducted widely, not only within the Sydney Harbour National Park, a known area of habitat for the small penguins, but also throughout many local councils as they engage in intensive red fox control. While consuming the poison does eventually result in death, it first causes the foxes to engage in ‘manic running, yelping, shrieking, and then collapse and convulsions’, all of which usually lasts several hours” (Van Dooren, 2011). This very controversial, lethal control method was allowed to continue largely as a result of the simplistic divide that exists between native and exotic species within conservation legislation in New South Wales. This mass slaughtering continued even after biologists had raised significant ecological concerns with the eradication of the foxes, as removal had been known to lead to increased mortality among some native birds and animals throughout the area. Additionally, without the foxes, rabbit populations have on occasion exploded, resulting in additional problems for valued native herbivores and plant species. 

Van Dooren (2011) goes on to discuss a considerable native threat to the little penguin population, the New Zealand fur seal (Arctocephalus forsteri). When proposing solutions for this issue, the fur seals were approached very differently than the foxes, largely in that they are presented as ‘native’ to the area, and therefore engaged in ‘natural predation’ of this colony. It is also highlighted that it is important to recognize that fur seals differ from foxes in that not every fur seal will eat the little penguin species, as a species. These seals are certainly not small penguin specialists; however, there are documented examples of New Zealand fur seal populations that relied quite significantly on them for a large part of their diet. The solution introduced to deal with this threat to the little penguin colony was essentially to ignore this issue. There was no mention of this native fur seal species in the protection and restoration plans for the small penguin population, indicating that since they are native to the ecosystem as the species of concern, there is no need to prevent their killing of the already shrinking population, an obvious double standard.

This article juggles with the problematic idea of coining the species’ “invasiveness” as it applies to the various predators of these small penguins. Van Dooren (2011) also uses these case studies to explore the influence of these rhetorical distinctions in determining species as threats, not only in the context of the continuity of this penguin colony, but also in a broader ecological sense. Additionally, Van Dooren (2011) mentions that in certain cases, native species have been referred to as “invasive pests,” largely when they induce prolonged substantial damage to other native species. Van Dooren (2011) argues that along with these “invasive” natives frequently comes a recent history of human actions altering their population or distribution, resulting in their destructive title. So we ask, in the absence of the convenient simplification of harmful being synonymous with invasive, how do we determine appropriate regulatory actions to take against these species, or if we should act at all? What kinds of interventions, either from humans or nonhumans, are warranted, and which are deemed too extreme? Van Dooren (2011) argues that by placing a binary divide between native and exotic species, experts fail to acknowledge the dynamic and ever-changing nature of the ecological systems these species exist in. These divides frequently act as a justification for which species should be protected or destroyed, as their values are intrinsically tied to the terminology

One critique that I have of this article is just how heavily it leans into critique. While Van Dooren (2011) does a great job at pointing out several of the extremely problematic aspects of designing and enacting invasive species management plans, both on an ecological and ethical level, he falls flat in describing any specific actionable solutions for these issues. Furthermore, Van Dooren (2011) creates his narrative through very rose colored glasses, leaning very heavily into the idea that killing should be a last resort. While I do not necessarily disagree with the fact that killing should be taken very seriously, and every other option should first be examined, it is willfully ignorant to state that there is never a case where it is the most practical solution. Finally, on an accessibility level, this article is written in a form that relies very heavily on jargon. This article discusses various aspects of invasive species management that must take place in highly human-dominated, urban, and suburban areas. As a result, Van Dooren (2011) has structured this article in a way that is more palatable to the general public; however, he did not translate that same consideration to the vocabulary of the article. This article could definitely be improved upon by relying less on jargon and making the language more accessible to a multitude of audiences. 

Source: 

Van Dooren, T. (2011). Invasive species in penguin worlds: An ethical taxonomy of killing for 

conservation. Conservation and Society, 9(4), 286. https://doi.org/10.4103/0972-4923.92140

Introduction

The global lockdown beginning in 2020 allowed some wildlife to venture into cities, like foxes, coyotes, and birds. The paper “What can we learn from wildlife sightings during the COVID-19 global shutdown?” by Zeller et al. (2020) in Ecosphere encompasses both an ecological and social study. The author uses citizen science data to explore changes in wildlife observations during the pandemic. This paper caught my attention due to the discussion in class about the pause in human activity during the pandemic and how urban wildlife behavior is intertwined with our presence.

Summary

Zellmer and colleagues analyzed citizen reported wildlife sightings from platforms like iNaturalist and eBird, comparing data from the early months of the pandemic to previous years. The purpose was to figure out whether wildlife actually became more abundant in cities during lockdown or if people only noticed a greater abundance of animals because they were at home and actually paying attention.

Results

They found mixed evidence. Reports increased of wildlife sightings in many urban areas, but this does not mean that there were necessarily more animals. Species that appeared more frequently in urban environments were coyotes, deer, and foxes. These were species that typically avoid dense human spaces. The paper emphasized that changes in behavior varied by species, city, and the degree of lockdown strictness. They ultimately, highlighted, that human movement can drastically alter the visibility and distribution of urban wildlife. A big portion of the paper is dedicated to acknowledging what the data cannot prove due to observer effort bias, detection vs. abundance, and heterogeneity among cities. The article never comes to an exact conclusion that wildlife increased in urban areas during lockdowns, but rather raises possibilities and promotes cautious interpretation.

Critical Reflection

This study is strong in that it used this rare global event as a large-scale natural experiment. The use of citizen science allowed for fast data collection and broad spatial coverage during a difficult time. The article is also rightfully cautious in not claiming “nature reclaimed cities” and instead acknowledging biases in observation and sampling. This underlines that this study is more of an analysis of human behavior rather than animal abundance. All in all this reflects on their credibility, making it a more reliable source. However, the authors could have gone further in correcting biases, rather than simply acknowledging it. For example they could have implemented observation models and categorization, which could have helped them separate real life wildlife increases from high detection rates. Furthermore, the study focuses on the early stages of lockdown in 2020, when in reality animals responses to the lockdown evolved over time. A study comparing all years of lockdown would test whether behavioral flexibility persists. Further studies could combine citizen science with automates monitoring, such as camera traps, sensors or tracking collars. Additionally, comparing results across continents could reveal cultural or infrastructural influences on how wildlife adapted depending on the density of buildings, size of city, noise pollution etc.

Work Cited

Zellmer, A. J., Wood, E. M., Surasinghe, T., Putman, B. J., Pauly, G. B., Magle, S. B., Lewis, J. S., Kay, C. A. M., & Fidino, M. (2020). What can we learn from wildlife sightings during the COVID-19 global shutdown? Ecosphere, 11(8), e03215. https://doi.org/10.1002/ecs2.3215

In Corser’s (2001) peer-reviewed article regarding Aneides aeneus, a green salamander species found in the Appalachian Mountains, he found that the species suffered critical population declines during different periods spanning across multiple decades. The first decline was noticed in the 1970s, with another major decline found in the late 1990s. Corser attributed these population losses to habitat destruction, overcollection, climate change, and epidemic diseases.

Most amphibian species that have declined in North America are those found in mountainous regions experiencing localized population decreases. These are typically isolated populations, separate from others, representing a localized population decline rather than a species-wide collapse. Additionally, other amphibian species outside of salamanders were found to have even worse population declines due to their (at the time) lack of understanding regarding salamander populations. During the 1990s, following reports of amphibian declines, many researchers were first introduced to the concept of amphibian decline as a present conflict in wildlife ecology (Corser, 2001).

This article focused on a specific species throughout the 1990s when this new issue was brought to the forefront of the wildlife conservation community. Corser chose to study Aneides aeneus, a green salamander found in the “Blue Ridge Escarpment” or BRE. The Blue Ridge Escarpment, according to VisitGreenvilleSC.com, is “the line at which…the Blue Ridge Mountain range plunges down towards the rolling foothills of South Carolina,” which illustrates the interesting ecological niche that these salamanders play a role in. According to Corser (2001), they “occupy one of the most specialized and xeric niches of any eastern salamander.” They live in crevices and short outcroppings along tributaries and gorges of the BRE.

Due to the increased observation of salamander decline apart from the first observed drops in 1970, Corser (2001) chose to observe and collect data to determine the population sizes in the BRE. In areas found along the BRE in Georgia, North Carolina, and South Carolina, Corser located the previous scientist’s survey locations from the 1970 study and attempted to recreate the same observations. Corser found thirteen locations to monitor the green salamander populations, seven of which were exactly from Snyder (1971). This gave Corser both new and previous observational areas to research the rock crevices for brooding females. This method was proven to be significant for Snyder’s (1971) research. Corser surveyed these areas once a year from 1991 to 1999, during the last week of July or the first week in August. This provided a great opportunity to locate brooding females and estimate both population size and fecundity.

By using the MONITOR Monte Carlo linear regression model, Corser (2001) was able to determine that the population decline at the historic sites from Snyder’s (1971) paper remained low and continued to decline. In contrast, the new populations found during the 1991 to 1999 survey period were not significantly declining when compared to the already decimated populations from the 1971 observations.

Finally, Corser (2001) was able to conclude that a myriad of factors—whether that be clear-cutting, habitat loss, increased levels of DDT in salamander systems, or other anthropogenic influences seen in nearby amphibian species—might be contributing to the decline and lack of population rebound. With the limited number of sample sites and a rejection of the null hypothesis for the green salamander populations, one could conclude that there are likely many unknown areas Corser was not able to find, since their ecological niche is so specific and difficult to locate within rock crevices. If more samples were found and observed over longer periods of time, future studies could see more significant results, one way or another. This could further prove that their populations are, in fact, declining and are unable to rebound from ongoing environmental and human-caused stressors.

References: Corser, J. D. (2001). Decline of disjunct green salamander (Aneides aeneus) populations in the southern Appalachian Mountains. Biological Conservation, 97(2), 119–126. https://www.sciencedirect.com/science/article/pii/S0006320700001002?via%3Dihub

Snyder, D. H. (1971). The function and evolution of brooding behavior in the plethodontid salamander Aneides aeneus. Copeia, 1971(2), 385–390. www.visitgreenvillesc.com/listing/blue-ridge-escarpment/6237/

https://www.proquest.com/docview/3064395118/9B10DEAE6BFE47A4PQ/7?accountid=12725&sourcetype=Scholarly%20Journals

This study examines how more frequent and often negatively perceived interactions with wildlife is worsening with urban expansion. This is important because wildlife conservation largely depends on human tolerance for wildlife. The study area was the Metropolitan Atlanta, which contains 5.9 million people 45% forest cover. They examined wildlife related calls with complaints related to wildlife in neighborhoods, sick injured or orphaned animals, and the rest pertaining to threats to humans, domestic animals or other conflicts. The study then goes into demographic distributions, racial inequality with environmental justice, and quality of green spaces. They designed an online survey with demographic and geographic questions (like zipcode/neighborhood definition), whether they owned pets, or had gardens and how often they were tailored to. They selected 15 species for reporting based on frequency of past reports, and those that were likely to elicit different reactions from participants. These were matched with attitude rankings and emotional responses to different animals, as well as whether they would prefer populations to change.

The results were as follows: a little over half of the respondents were female and black. 68% of respondents lived in a house and 67% with a garden. Respondents’ gardens often contained lawn and flowering plants, thereby providing habitat for urban wildlife. The most frequently reported conflicts were raccoons raiding trash cans, squirrels, chipmunks, rabbits and deer damaging landscaping, and vehicle collisions with deer. Respondents’ attitudes toward species were positive predictors of tolerance. For example, those who were mutualistic (value wildlife and human harmony) in their beliefs were also more likely to be tolerant of coyotes, deer, opossums, snakes etc. Those who had threatening experiences with these animals had less tolerance. As far as demographics go, black respondents were less tolerant of foxes but more tolerant of squirrels and chipmunks, while Hispanic respondents were less tolerant of owls and rabbits. This could be due to the green space difference in certain minority communities and the species they interact with.

The methodology clearly presents a range of possibilities for interactions, giving participants ample descriptions of wildlife scenarios as well as matching them to frequency of occurance. The wildlife value orientation scale from traditionalist to mutualist views gives clear context for how certain participants may have responded differently to the same wildlife interaction. Equal and intentional sampling of minority groups allowed for clear analysis and comparisons between groups. The main deficit of this study is the amount of factors being assessed at once and its reliance on other research. In the discussion, the references to other studies explained the relationships more in depth than most of the correlations found within the study. They unexpectedly found an inverse relationship between self efficacy (protection from wildlife) and snake tolerance. This may be a result of the design of self-efficacy statements, which were generic and not specific to each focal species. There must be more specific relationships defined and more focus on a few variables, like emotions and conflict interactions, as well as demographics for example.

Future research should focus on implementation of the Urban Wildlife Program and community science’s influence on people’s responses and attitudes. I think more research on green space distribution and other factors besides gardens (like canopy cover) in black and minority neighborhoods would give more insight into their tolerance levels and interactions. I would love to learn more about how minority communities may benefit from urban wildlife, or be disproportionately harmed by it.

This paper caught my eye because I think there are more effective ways of managing human-wildlife conflict that have not been addressed. While agencies typically focus on education and conflict mitigation, more proactively increasing wildlife tolerance may be a more effective long term strategy for conservation. Because prior conflicts with species rarely influenced tolerance, more focus should maybe be reinforcing positive emotions and interactions, as well as just more opportunities for communities to safely observe wildlife and their behaviors.

Overview

I chose this article as it relates to urban wildlife management in the context of urban planning and optimizing cities for wildlife diversity and connectivity. The study focuses on locally rare species representing a wide range of taxa, offering insights into how urban areas can be designed to support biodiversity through habitat corridors. The authors evaluated patterns of habitat availability and connectivity for nine rare species: two insects, three turtles, two snakes, one bird, and one bat across four urban regions in Michigan, USA. These species were selected because they are regionally rare (ranging from state-listed to federally endangered) but still maintain populations within urbanized landscapes. The study aims to identify how urbanization influences habitat structure, connectivity, and opportunities for conservation planning.

Methods

The researchers selected nine focal species representing several taxonomic groups known to be regionally rare. Species occurrence data were compiled from multiple reputable databases, including the Michigan Natural Heritage Database (MNFI), the U.S. Fish & Wildlife Service (USFWS), HerpMapper, iNaturalist, and eBird. To ensure data reliability, only verified MNFI and Research Grade iNaturalist records were used, and records prior to the year 2000 were excluded. Protected areas were mapped by merging all federal, state, county, local, and NGO-managed lands from MNFI GIS layers, excluding disturbed greenspaces such as golf courses.

Urban boundaries were defined using U.S. Census Bureau criteria areas with populations over 50,000 and a density of at least 1,000 people per square mile, with adjacent tracts of 500 people per square mile included as urban periphery. This classification allowed the researchers to analyze habitats embedded within realistic urban-to-rural gradients. Connectivity analyses were then conducted within selected urban regions that met these demographic criteria and contained overlapping species occurrences.

To establish biologically relevant study sites, the team generated 5 km buffers around each species occurrence, encompassing estimated dispersal ranges for most taxa. Overlapping buffers within 10 km of each other were merged, and convex hull polygons were created around the merged clusters. These polygons were then expanded by 5 km to define final analysis areas representing zones of multi-species co-occurrence. This ensured that the study captured both urban and adjacent non-urban habitats crucial for species movement.

Species distribution models (SDMs) were developed for each focal species using an “ensemble of small models” (ESM) approach, which performs well with limited occurrence data. Occurrence points were spatially thinned to a minimum spacing of 1 km to prevent overrepresentation of dense populations, with a target of at least 20 records per species. In cases of limited data, such as the American Bumble Bee, surrogate models were used (the Black and Gold Bumble Bee model).

Road networks were not included in the SDMs directly to avoid false habitat associations, but they were incorporated into resistance surfaces used for connectivity modeling. Roads were buffered by 30 m and assigned species-specific cost values to represent movement resistance: 1000 for reptiles (reflecting high road mortality), 500 for birds and bats (behavioral avoidance), and 250 for bees (potential roadside habitat but increased mortality risk). These road-cost rasters were then merged with each species’ SDM-based resistance surface.

Connectivity was evaluated using multiple tools. Circuitscape was applied to identify likely movement corridors and high-current areas representing multi-directional pathways, while Graphab was used to analyze habitat patch importance and network structure through the dPCk metric. Fragstats provided quantitative measures of landscape configuration, including connectance and clumpiness. Together, these tools revealed both broad and fine-scale patterns of connectivity and potential barriers for each species within and around the urban zones.

Results

Findings showed that many species retain moderate to high habitat proportions within urban landscapes, but the strongest connectivity corridors are typically located outside urban boundaries. Riparian and wetland zones were identified as critical linkages, especially for aquatic and semi-aquatic species such as turtles and snakes. Among the cities, Kalamazoo and Detroit North exhibited the most extensive multi-species connectivity networks, while Benton Harbor and Detroit Southwest showed more limited urban movement potential. Turtles had the highest habitat availability overall, suggesting persistent wetland and forest-edge habitats, whereas grassland species like Henslow’s Sparrow and bumble bees had the least. The study also emphasized that smaller, well-placed habitat patches often contribute more to overall connectivity than larger, isolated ones.

Fig. 3. Map of study area (a) showing Least Cost Paths (LCP’s), (From left to right) Protected areas, barriers impeding connectivity, and current species density.

Critiques & Reflection

This study effectively demonstrates how integrating multiple connectivity modeling tools can inform urban conservation planning. The inclusion of diverse taxa from reptiles to insects gives the findings broad ecological relevance. I found it particularly valuable how the authors linked quantitative spatial analysis to practical conservation implications, such as protecting riparian corridors and small but strategically located habitat patches.

The article does a great job of emphasizing the importance of riparian corridors and buffers, which in my opinion are not adequately regulated under today’s environmental laws. These areas are critical for maintaining ecological connectivity in urban regions, yet they are often overlooked in planning and development regulations.

Although the paper briefly mentions genetics, I believe this is an area that deserves greater focus. Genetic diversity and gene flow are essential components of wildlife corridor restoration, especially for populations that have become isolated by urbanization and experienced bottlenecking. Wildlife corridors are not only about providing safe passage between fragmented habitats,  they also serve as vital habitat themselves, supporting long-term survival, breeding, and dispersal. Many isolated reptile populations, for instance, have not experienced genetic connectivity for centuries due to habitat fragmentation. Snakes are particularly vulnerable to urbanization and the lack of corridors, as they are frequently forced to cross roads where they face high mortality rates, often being killed by vehicles, sometimes even intentionally, despite their protected status.

Despite these challenges, the approach presented in this study offers a replicable framework for urban planners seeking to incorporate biodiversity goals into development strategies. It highlights that even within heavily modified landscapes, thoughtful urban design and targeted protection efforts can sustain rare species populations and maintain ecological connectivity.

Reference

McCluskey, E. M., Kuzma, F. C., Enander, H. D., Cole-Wick, A., Coury, M., Cuthrell, D. L., Johnson, C., Kelso, M., Lee, Y. M., Methner, D., Rowe, L., Swinehart, A., & Moore, J. A. (2024). Assessing habitat connectivity of rare species to inform urban conservation planning. Ecology and Evolution, 14(3), e11105. https://doi.org/10.1002/ece3.11105

A study conducted in the urban desert environment of Phoenix, Arizona, examined the impact of climate change on bird biodiversity. Researchers found that there was a connection between impervious surfaces and rising land temperatures and declines in bird abundance and species richness, specifically during the winter. This study uses extensive long term data from 2001-2016 to gain information on the topic and while a lot was gain from extensive data there does not seem to be concrete solutions yet, for urban planning. The study shows a functional group analysis that shows different bird roles like pollinators, insectivores and other responds differently to environment changes with different ecosystem services. Although, temperature and urban development cause a decline in bird diversity, impacts can be very different. This means there cant be one strategy, but multiple for each specific group, in order to conserve. One key solution suggested was “enhancing vegetation”, a model showed that increased vegetation were associated with higher bird numbers. Planting native trees or shrubs may help reduce the negative effects of impervious surfaces and rising temperatures in urban location. Enhancing and managing urban vegetation are just a few strategies that can help to support wildlife and maintain essential ecosystem services.

https://esajournals-onlinelibrary-wiley-com.prox.lib.ncsu.edu/doi/epdf/10.1002/eap.70063

In this article, Dupuis-Desormeaux et al. (2022) discuss the manner in which introduced species are frequently labeled as “bad,” without first considering their potential to promote the ecological functions of degraded ecosystems. This paper is extremely significant in the world of conservation work, as it asks its audience to completely reevaluate what an invasive species means for an ecosystem, and for most conservation biologists, that would mean considering an invasive species as beneficial. The species that Dupuis-Desormeaux et al. (2022) ask their audience to reconsider is the red-eared slider (Trachemys scripta elegans), but the idea presented by this paper goes much further than just the red-eared slider. The paper suggests that under certain circumstances, some invasive species may be beneficial to an ecosystem, or at least contribute to some ecosystem function. This idea is relatively foreign to most, as we are taught on a large scale that invasive species are damaging to ecosystems. This paper introduces that invasive species may not just be bad for ecosystems, and that they could even be used methodologically to repair damaged ecosystems. 

Dupuis-Desormeaux et al. (2022) ask audiences to completely reevaluate how they view the red-eared slider, considering beyond the many threats that they pose, and instead assessing how they may perform as “contributors to ecosystem functions in degraded” habitat. Turtle species globally provide paramount ecosystem functions. This article classifies these functions into six categories: biomass contributions, energy flow and scavenging value, mineral cycling and bioaccumulation, trophic status, seed dispersal and germination enhancement, and bioturbation in soil dynamics. Like most turtle species, red-eared sliders perform all six of these ecosystem services; however, as Dupuis-Desormeaux et al. (2022) highlight, this species is deemed extremely undesirable, even in habitats where native turtles have been eradicated and are no longer able to perform such services. It is important to note that this article does not advocate for the further release of red-eared sliders into wild and natural spaces; however, it offers that in the current ecosystem of turtle populations declining precipitously as a result of increased anthropogenic pressures, especially overutilization and habitat destruction, red bearded slides, being the prolific species that it is, may be able to provide ecosystem restoration services in habitats that have become to degraded for native species to occupy. 

While reading this paper, I began to question whether red-eared sliders have been studied sufficiently to warrant their classification as an invasive species. In several sections discussing the ecological effects of red-eared sliders in non-native habitats, the author notes that many of the proposed impacts remain inconclusive due to a lack of comprehensive research. This raises an important question: what criteria must be met for a species to be officially designated as “invasive”? If, as the author hints, the red-eared slider has never been proven to have all of the suggested negative impacts on ecosystems, what is distinguishing the turtle as an invasive species rather than an introduced species? However, this species has been proven and is largely known as a prolific invasive species. Given the red-eared slider’s listing as one of the top 100 worst invasive species by the IUCN due to its significant global ecological impacts, allowing populations to remain unchecked poses a legitimate risk of rapid and uncontrolled population growth.

The author suggests that in some cases, it may be beneficial to allow red-eared sliders to remain in their non-native environments, as they may be filling vacant ecological niches. While this idea may seem reasonable in the short term, the paper also highlights that more habitats are becoming suitable for these turtles, potentially allowing their populations to expand further. If their numbers continue to increase, it is plausible that they may enter ecosystems where they could have detrimental effects. Additionally, if red-eared sliders are allowed to persist in non-native areas, there is the possibility of hybridization with native turtle species, such as the yellow-bellied slider. This poses further issues concerning the significance of said hybridization, and its potential to be used to increase genetic diversity rather than eradicate local existing species. This case is also quite interesting as although hybridization is a natural phenomenon, the global span of this species could have broader implications, contributing to the creation of several hybrid species.

Reference: Dupuis-Desormeaux, M., Lovich, J.E. & Whitfield Gibbons, J. Re-evaluating invasive species in degraded ecosystems: a case study of red-eared slider turtles as partial ecological analogs. Discov Sustain 3, 15 (2022). https://doi.org/10.1007/s43621-022-00083-w

Overview:

This study seeks to understand more about urban wildlife management in U.S. cities, specifically looking at predator management and rodent control. It looks at rodenticides, as well as non-lethal forms of rodent control. Human-wildlife coexistence and interactions are also discussed in this article.

Methods:

The authors first looked wildlife management and rodent control governmental policy documents, newspaper articles, and fact sheets from wildlife organizations. They then chose fourteen urban wildlife management plans that prioritized nonlethal management of predators and rodent control. They conducted a direct content analysis qualitatively on the wildlife documents. The analysis consisted of each researcher reading the documents and finding relevant themes, exchanging notes with each other, and lastly discussed together the themes/subthemes that felt most relevant to the group about co-existence based urban wildlife management, shown in the table below.

Results:

The researchers found that the urban wildlife plans desired for human-wildlife coexistence. Additionally, they found that the plans were against eradicating species that are considered “nuisance species” and that some cities were okay with living near predators that may pose a risk for humans. Humans should instead get used to living with them, with coyotes being included in this plan as long as it is in the boundaries that they should exist in. The plans also are against killing urban wildlife, unless the animal is seriously aggressive. Normalizing human-wildlife interactions that are unproblematic are also important to show the public that interactions with urban wildlife can be positive.

When looking at rodent control, rodenticides have been most popular to control rat populations. However, predators that consume rats that have poisoned have also perished because of the poison that was in the rats. Thus, there has been more of a movement to ban these rodenticides. Some nonlethal methods to control rat populations are mostly preventative measures that limit the possibility of rat populations to occur in a specific area.

Reflection/Critiques:

I found this study to be very informative when looking at urban wildlife plans from around the United States. I also found it interesting what the urban wildlife management plans had to say about predator management. However, I do think that they could have benefited from incorporating data about different types of human attitudes toward wildlife. Going more in depth about the history of certain species and why humans feel a certain way towards them could be helpful as well. Lastly, I found the data analysis to be lacking a bit and not as professional as I would have thought.

References:

Hunold, C., & Mazuchowski, M. (2020). Human–wildlife coexistence in urban wildlife management: Insights from Nonlethal Predator Management and rodenticide bans. Animals, 10(11), 1983. https://doi.org/10.3390/ani10111983 

Background and Overview

With two-thirds of humanity expected to live in urban areas within the next few decades and cities expanding across the globe, we’re creating entirely new ecosystems. While much attention has been paid to how urbanization affects wildlife abundance and diversity, less is known about how cities influence disease transmission among wildlife populations. This is a critical gap in our knowledge, especially since many wildlife pathogens can also infect humans or threaten already vulnerable animal species.

Cities create dramatic changes in the landscape: more impervious surfaces like roads and buildings, altered microclimates with heat island effects, concentrated human populations, and significantly reduced biodiversity. These changes don’t just affect which animals live in cities—they fundamentally alter how diseases spread among wildlife. Researchers hypothesized that urbanization would influence wildlife–pathogen interactions through several mechanisms: changes in host biodiversity, altered contact rates due to resource provisioning, environmental contamination, and climate modifications.

Methods

Rather than conducting new field experiments, this paper synthesized existing research on wildlife diseases across urban–rural gradients. The authors drew from case studies spanning multiple continents, taxonomic groups, and pathogen types. They examined how urbanization affected three key components of disease transmission: hosts (the animals that carry diseases), pathogens (the disease-causing agents themselves), and vectors (organisms like ticks and mosquitoes that transmit diseases between hosts).

The researchers categorized urbanization effects into several major themes: biodiversity loss and the dilution effect, resource provisioning and host contact rates, pathogen exposure and pollution, and climate-related changes. For each theme, they identified specific host–pathogen systems that illustrated how urban landscapes alter disease dynamics. Examples ranged from Lyme disease in white-footed mice in northeastern United States suburbs to toxoplasmosis in sea otters off the California coast. Urbanization was typically quantified using measures like human population density, impervious surface coverage, and distance from urban centers.

Results

The picture that emerged from this synthesis is complex and sometimes contradictory. Overall, urbanization reduces the abundance of many wildlife parasites simply because it eliminates most wildlife species and their associated pathogens from urban cores. However, for species that do adapt to city life, disease dynamics can intensify in surprising ways.

One of the most interesting findings involves the “dilution effect.” In areas with high biodiversity, disease transmission can actually decrease because vectors like ticks feed on multiple host species that vary in their ability to spread pathogens. In urbanized areas with low host diversity, competent reservoir hosts (like white-footed mice for Lyme disease) can become proportionally more abundant, leading to increased infection rates in both ticks and humans. Similar patterns were found for West Nile virus, where areas with lower bird diversity showed higher infection rates.

Resource provisioning in cities—both intentional, like bird feeders, and accidental, like garbage—creates hotspots where wildlife congregate. This dramatically increases contact rates among animals. Studies of urban raccoons showed that clumped resources led to higher population densities and increased prevalence of raccoon roundworm, particularly among juveniles. Interestingly, the spatial distribution of resources mattered as much as their abundance.

Environmental contamination also played a major role. Urban runoff carrying cat feces led to toxoplasmosis infections in southern sea otters, with infection rates three times higher in areas of maximum freshwater runoff near human population centers. The urban heat island effect extended the activity period of disease-carrying ticks in Stockholm, coinciding with elevated tick-borne encephalitis cases.

Perhaps most concerning for conservation, the researchers found evidence that diseases maintained in abundant urban-adapted species (like gray squirrels or raccoons) can spill over to affect rarer wildlife species. The introduction of gray squirrels carrying a lethal paramyxovirus has contributed significantly to red squirrel declines in the UK, with the effect amplified by food provisioning that increases contact rates between species.

Reflection and Critiques

I find the complexity of these patterns fascinating—urbanization doesn’t simply increase or decrease disease risk; it fundamentally reshapes the entire disease landscape in ways that vary by pathogen, host, and specific urban characteristics. The idea that cities might reduce overall parasite diversity while intensifying transmission among adapted species makes intuitive sense and has important implications for both wildlife conservation and human health.

One strength of this paper is its recognition that multiple mechanisms can work in opposite directions. For example, supplemental feeding increases contact rates (bad for disease spread) but might also improve host nutrition and immunity (good for resisting infection). Similarly, milder urban winters could increase vector survival but might also help infected animals survive that would otherwise die from secondary causes like starvation. I appreciate that the authors don’t oversimplify these relationships.

However, this paper is a review rather than a primary research study, which means it’s limited by the quality and scope of existing research. The authors acknowledge this limitation and call for more experimental and modeling approaches. I would have liked to see more discussion of publication bias—are researchers more likely to publish and report cases where urbanization does affect disease dynamics, potentially skewing our understanding?

I also think the paper could have explored socioeconomic dimensions more deeply. They mention briefly that higher family incomes predict greater plant diversity in Phoenix, but urban ecology involves enormous variation in resource availability, green space access, and environmental quality across different neighborhoods. Disease risks probably vary significantly within cities based on these factors, not just across the urban-rural gradient.

The suggestion that urban planning could be used as a disease management tool is intriguing but feels underdeveloped. How realistic is it to design cities that maintain high biodiversity while supporting dense human populations? What would that actually look like in practice? This seems like an area ripe for future research, especially as cities continue to grow.

Overall, this paper does an excellent job of synthesizing a complex and emerging field. It raises as many questions as it answers, which is exactly what a good review should do. As someone interested in conservation, I’m left wondering how we can better protect vulnerable wildlife species from disease spillover while managing the very real urban-adapted reservoir hosts that sustain these pathogens. The intersection of urban planning, wildlife management, and public health will only become more important as urbanization continues its rapid global expansion.

Bradley, C. A., & Altizer, S. (2007). Urbanization and the ecology of wildlife diseases. Trends in Ecology & Evolution, 22(2), 95-102.