A Critical Review of Planning for the Future of Urban Biodiversity: A Global Review of City-Scale Initiatives 

The article I chose reviewed 135 plans from 40 global cities to find commonalities and areas of improvement in urban biodiversity planning. This paper reviewed these plans from an ecological perspective focusing on biodiversity and ecosystem services. However, urban ecology is an interdisciplinary topic and a social lens can be valuable for these reviews. Because there is such a high human population in urban areas, it is impossible to plan for biodiversity values alone. This article also does not consider the effectiveness of these plans in their review. Instead, they focus on finding relevant ecosystem attributes and uses of these attributes in urban planning. While it is important to show what planners have been focusing on in the past, it is also important to consider how effective these focuses have been in order to identify areas of improvement.

I was happy to see that community engagement is an important component of most plans. As I said earlier, cities are areas of high human population. It is inevitable that human opinions and actions will affect biodiversity. By educating citizens about biodiversity, ecosystem services, and the goals of your plan, we can move together to create a larger impact.

Overall, I think this was an important contribution to urban biodiversity literature. Using a large scale approach to planning assessment highlighted similarities between values of urban planners. In regards to the plans themselves, it is obvious from the findings of this article that plans for urban biodiversity conservation need to become much more specific. While they may be well intentioned, a plan without measurable goals and target species is not effective. Goals need targets in order to ensure their effectiveness and completion. Species specificity is important to ensure actual increase of species diversity.

Charles H. Nilon, Myla F. J. Aronson, Sarel S. Cilliers, Cynnamon Dobbs, Lauren J. Frazee, Mark A. Goddard, Karen M. O’Neill, Debra Roberts, Emilie K. Stander, Peter Werner, Marten Winter, Ken P. Yocom, Planning for the Future of Urban Biodiversity: A Global Review of City-Scale Initiatives, BioScience, Volume 67, Issue 4, April 2017, Pages 332–342, https://doi.org/10.1093/biosci/bix012

Fardell, L.L.; Pavey, C.R.; Dickman, C.R. Backyard Biomes: Is Anyone There? Improving Public Awareness of Urban Wildlife Activity. Diversity 2022, 14, 263. https://doi.org/10.3390/d14040263

With urbanization increasing, wildlife are increasingly being found in peoples yards and are relying on resources found in these yards. This also exposes wildlife to the effects of yard management, human activities, and impacts from peoples pets. Many people do not realize that their yards act as refuges for many species. This research aimed to provide a background knowledge to citizens about the importance of biodiversity within their lawns and educate them about the species found in their local area.

This study was conducted in two medium-low density urban areas located in Australia. Both of these areas were located near the 534 ha Glenrock State Conservation Area and many green spaces were dispersed throughout the area. Many small native mammal species occupy this area. It was also noted that two introduced mesocanivore species could be found within the study site: the red fox (Vulpes vulpes) and the domestic cat (Felis catus).

They conducted Household Activity Surveys within the study site to get a better understanding of the yard structures and activites that took place at peoples homes. Yard structure questions focused on the types of plants and grasses that could be found within the yard. The survey also asked questions on whether the yard had fences, flower beds, pavement, etc. They also conducted Backyard Animal Activity Surveys between the months of May-June of 2019 to observe the amount of wildlife present in peoples backyards. To do this they attached camera traps to trees and fences in peoples backyards. Homes with pets that were allowed in the backyard were told to keep letting their pets out as usual.

Out of 50 homes that completed the survey, 41 of these had observed wildlife within their backyards. 24 of the respondents stated that they also had a pet. Every property had a fence, but they type of fence varied from metal to wooden. More than half of them homes used fertilizers or pesticides in the yards.

This graph shows the correlation between wildlife found in peoples backyards and the different variables associated with the data that homeowners selected they have in their yards.

The results from the Backyard Animal Activity Survey showed that most animals were present in peoples backyards at night rather than during the day. The most common species found during night were the common brushtail possum. northern brown bandicoot, and the red fox. Native birds and the domestic cat were frequently observed during the day in more vegetative habitats in comparison to open areas. Wildlife were found more frequently in backyards where the yard was more easily accessible, there was reduced pesticide use, increased levels of antrhopogenic noise, and increased yard access by pets.

I thought this article was interesting as it dives deeper into the way that the choices we make when maintaining our personal backyards can have a direct impact on the local wildlife. One thing I wish they talked more about was the impacts of pets in the backyard on the prescences of wildlife. They brought up having pets quite a bit and even in the results you could see that yards with pets tended to have a higher wildlife prescence. I think it would be interesting if they touched on that aspect more as many people who do have pets will let them outside or even keep them in their backyard. I also am interested in the impacts of pesticides and fertilizers in backyards and how that could have negative impacts on wildlife who use these backyards as corridors. I think this study was interesting and could be used a tool to educate people on the way their yards have direct impact on wildlife.

Brazil, a global biodiversity hotspot, is home to an incredible 178 bat species, and surprisingly, nearly half of these species (84) have been documented in urban environments. In major cities like São Paulo to the urban forests in Rio de Janeiro, bats have found ways to coexist with humans in cities across the country.

Bats adapt by roosting in urban forest fragments, trees, and even man-made structures. Forest fragments are vital, especially for the third of species that rely solely on these green pockets for survival. Meanwhile, the flexible bats make use of a variety of human structures, from ceilings to abandoned buildings, proving their resilience in modified environments.

With 31 different plants supporting at least twelve species of bats, urban green spaces become essential food sources, offering fruits, nectar, and insect populations. Streetlamps attract insects, providing an easy meal for insectivorous bats, while others feast on the fruit-bearing trees of the city.

Bats, as reservoirs of zoonotic diseases, bring a unique public health dimension to urban wildlife. With parasites like rabies virus and Leishmania, monitoring urban bat populations becomes essential for public health. The study identifies 27 species carrying these zoonotic pathogens, highlighting the need for policies that balance bat conservation with public safety.

The authors emphasize that as urbanization expands, we need a conservation strategy for bats. Preserving urban green spaces and creating awareness about bats’ role in ecosystems—like pollination and pest control—are critical for harmonizing urban life with wildlife conservation.

Nunes, H., Rocha, F. L., & Cordeiro-Estrela, P. (2016). Bats in urban areas of Brazil: roosts, food resources and parasites in disturbed environments. Urban Ecosystems, 20(4), 953–969. https://doi.org/10.1007/s11252-016-0632-3

Riparian zones are interfaces between freshwater and terrestrial ecosystems. These zones provide several ecosystem services and support an immense amount of biodiversity. Riparian zones cover about 1% of southwestern North American landscape, yet the riparian zones contain an abundance of richness and wildlife. In western North America, most of these ecosystems have been degraded or altered. Efforts to restore these riparian ecosystems continue to grow and in urban settings watercourses are diverted from floodplains to protect urban infrastructure.

In this study they assess the responses of wildlife to habitat restoration and floodplain management efforts. The study site is located in Tucson, Arizona. Specifically, they assess communities of diurnal lizards and how they are affected by Pima County Regional Flood Control District efforts to flood control. Included in these efforts RFCD enhance habitats through vegetation seeding and planting, and water retention. The researched the lizards before and after the treatment in a nearby tributary and a major river course.

It was found that restoration efforts mitigated the impacts of flood control management and provided benefits for some species. A tradeoff was identified in the data as there were negative impacts identified in at least one species of lizard. Terrestrial species with faster maturity times recovered faster than arboreal species with longer maturity times. Also the data suggests that management efforts should be paired with restoration efforts to maximize human and wildlife benefits.

I honestly do not feel that the study could improve. I found zero areas to negatively critique. The researchers conducted this study over several years, they provided a control experiment testing the area before undergoing restoration and compared that to the data they collected after the restoration and management efforts. They also went into distinct detail on both trait-dependent variation responses and context-dependent variation responses using the hard data collected throughout the experiment. This experiment is solely based on the effects against diurnal lizards, but I feel this is great framework to conduct in several other species to compare if management and restoration efforts are positive and neutral to other species affected in the area.

Wyman, Jules T., et al. “Long-Term Impacts of Urban Floodplain Management and Habitat Restoration on Lizard Communities in a Sonoran Desert City.” Ecological Engineering, vol. 197, Dec. 2023, doi:https://doi.org/10.1016/j.ecoleng.2023.107121.

The human population in urban areas will increase by 2.7 billion from 2010 to 2050. Vertebrates such as amphibians are under threat, about 40% of amphibian species are threatened with extinction. Urban development affects around 950 amphibian species with extinction. This paper stresses the concerns about how amphibians are some of the least studied vertebrate groups in urbanized landscapes, and how most land management is derived from studies of a few common species mostly leaving out amphibians and in turn failing to cater to all affected species leading to a higher risk of decline.

The researchers studied the distribution of pond-breeding frogs during breeding season in an area consisting of rural, forests, and urban areas. The site was focused in southeastern Australia, specifically it was conducted between Nowra and Booderee National Park.

The area is mostly dominant with native eucalypt forests and wetlands, consisting of both urban and rural areas. The researchers surveyed a total of 28 ponds within the study area boundaries. Frog calls were recorded at ponds during breeding season as this is when peak calling activity occurs. The researchers did state that two sites were not surveyed in urban areas due to vandalism and access, which I thought interesting as this could skew the data, especially since we are specifically looking at urbanization effects.

Aquatic and terrestrial variables were measured, variables such as water body size, and cover of surface vegetation. For this study they also took into account an exotic fish species, the eastern gambusia, because of its negative impact on frog populations. Personally, I feel this is an important factor to consider when studying specific species. This framework could be implemented when studying other species, it would obviously vary based on location. I believe the measurement of the exotic fish factor to be short. The researchers performed one five-minute visual search and placed a trap in the pond for three days. I don’t believe that to be maximizing efficiency on that specific factor, but data was captured, nonetheless.

It was found that some frog species had a positive association to urbanization while others had a negative association. It is known that the number of roads has a negative correlation to frog species richness. The paper suggests biodiversity metrics such as total species richness may underestimate urbanization impacts. It is still suggested that urbanization is a key driver in loss of pond-breeding frogs in the study region. Only one breeding season was examined in this study, yet the researchers expect the patterns of occurrence to be common to what was quantified and reflected in this study. Ultimately it was concluded that uncommon frog species are more sensitive to terrestrial modification where common frogs respond more to local aquatic variables.

I felt this paper was great at identifying the environmental variables that correlated to uncommon and common frogs. I did feel the paper lacked the measurement of environmental conditions. An example would be humidity and soil moisture. I feel the study could have been constructed in the manner of grouping the different study sites based on these factors rather than consolidating them to a basic body of water label. Also, the sites were based on urban, rural, and forested areas, the lack of knowledge on the history of the urban study sites I feel affected the data presented. The reader does not know if the urban areas are settled, or newly constructed. I feel knowing if the frogs have adapted to the changed environment or are adapting is crucial to scaling the impact of urbanization.

Villasenor, Nelida R., and Don A. Driscoll. “The Relative Importance of Aquatic and Terrestrial Variables for Frogs in an Urbanizing Landscape: Key Insights for Sustainable Urban Development.” Landscape and Urban Planning, vol. 157, Jan. 2017, p. 26–35, doi:https://doi.org/10.1016/j.landurbplan.2016.06.006.

https://doi.org/10.3389/fevo.2020.576665

Growing urbanization has displaced many animals and has led to the rapid adaptation of animals across many taxa. Recently, it has been an area of study to determine what adaptations are taking place in order for species to be more fit for an urbanized environment. This article focuses on the different types of behavioral changes and which animal orders are being observed successfully adapting to urban environments. Among the 83 published papers that were included in this review, there were 44 distinct behaviors and 155 individual occurrences of behavior changes in urban areas. The observations, behaviors, and number of occurrences for each respective behavior change all have the potential to support successful urban wildlife management and conservation. 

Considering the issues with their methods of retrieving relevant peer-reviewed publications, the authors did not agree upon the definition of “urban” for their search engine. This led to a broad overview of papers that were not consistent with their determined levels of urbanization. Also, they excluded any articles that were not in English or reliably translated. Although this is purposeful in order to not misinterpret results/findings from the paper, this may also mean that there is a large body of literature that is not considered, which also limits the geographic scope of the literature review. This is demonstrated by the fact that 52% of their data was from North America, followed by 20.5% from Europe. Additionally, the authors did not include any papers that are inaccessible via university resources or general internet access. This makes it easy for readers/researchers to locate the literature cited and find the primary research, but the authors could have included a section encompassing data they accessed via communication with the primary research authors to expand the data set that they analyzed.

The results showed that the most abundant behavior type studied was the alert response, followed closely by spatial change. Alert response was seen as changes in vigilance/caution behavior and was shown to both increase and decrease in urban areas. Spatial behavior was commonly shown as a decreased home range. Other common trends were increased nocturnality, a shift in resource selection, increased boldness, and increased exploratory behavior. Behaviors were sorted by animal order and then within each order broken up by guild (carnivore, herbivore, omnivore). The results of this study could have included a snippet about broad behaviors like shifting resource selections to give the readers insight as to why an animal would be altering its food source (Was the shift in resources due to abundance? Nutrition levels?)

Although there is a clear indication that species are responding behaviorally to the urban environments, the authors suggest that there are underlying mechanisms like region/ resource availability that act as external factors to further effect the adaptive behavioral response. Future research can be improved by being more inclusive of mammalian species, herbivores (especially deer/raccoons), and being aware that behavior is multi-directional/fluctuating. Ultimately, this research can be insightful for city planners, wildlife managers, and urban residents since human-wildlife interactions may be resulting from these potentially predictable behavioral changes.

Ritzel, K., & Gallo, T. (2020). Behavior change in urban mammals: a systematic review. Frontiers in Ecology and Evolution, 8, 576665.

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.