Urban Waterfowl Population Management

Posted on by Matthew Samuel Pugh

Overview & Background: In the peer-reviewed journal article Urban waterfowl population: Ecological evaluation of management and planning (Greer, 1982), we see urban ducks observed and studied in order to determine early morning congregation habits and location. This study followed these populations, which consisted primarily of mallards, in Puyallup, WA. As we see more and more urban development in areas with adjacent rural habitats, waterfowl and other vertebrates are forced to adapt to stricter conditions. In these areas, waterfowl struggle with several habitat-related issues, such as habitat size and nesting condition/success. Many factors play into these aspects of survival in urban environments. Without proper habitat size or conditions that resemble the complexity of more rural areas, we see less species diversity.
Methods: The researchers took vegetation surveys and waterfowl counts in four locations in the Washington area. The four locations were: Dairy Stream, Pumphouse, Dairy Lagoons, and DeCoursey Pond. The vegetation surveys showed an abundance of reed canarygrass, turf grass, and pasture grass. Cover, frequency, and dominance were values that Greer calculated from these surveys. Along with the vegetation sampling, there were waterfowl head counts and monitored nesting success observations. Over the course of 14 months, Greer counted and collected data on the number of waterfowl found in these four locations at predictable times in the morning. The Shannon Index was used to determine the species diversity in these areas. For statistical analysis, ANOVA, Duncan’s multiple range test, and discriminant and cluster analysis were utilized.
Results: Over the course of the survey, Greer observed 13 different species of waterfowl, with mallards being the most abundant. They were also found to be the only species nesting locally. Other species, such as American wigeon, bufflehead, scaup, and gadwall, were present seasonally but did not nest in the study area.

The Dairy Stream location was somewhat supportive of several species such as mallards, wigeons, and buffleheads. However, the most supportive location was DeCoursey Pond. It had the highest species diversity and supported both dabbling and diving ducks due to the pond’s size and complexity compared to the others. The Dairy Lagoons primarily housed mallards, with low diversity for other species, though diversity improved slightly when mallard numbers were less dominant. Finally, the Pumphouse had the lowest species richness and was mostly dominated by mallards when feeding occurred. There was very little nesting success overall, and nesting was only attempted by mallards. This was due to low nesting cover, disturbance, and intraspecific aggression from other mallards. In all, DeCoursey Pond was the most complex and deep site, resembling rural environments that waterfowl were more adapted to, which provided a greater opportunity for them to thrive. By contrast, the lower diversity areas such as the Pumphouse were more frequently disturbed by humans and interfered with the natural behavior of more sensitive species.

Reflection/ Critique: After reading over the study and its findings, I have a few comments and possible improvements. I thought the vegetation sampling was conducted well and helped contextualize the environments these waterfowl were around and what they were interacting with. This gives clues to how and why species diversity might be so different in one area compared to the next. However, one area I thought was understudied was the possible predator or human interaction with the waterfowl. Predators, especially urban wildlife predators, could be a significant factor influencing lower species diversity in some locations. If predators were observed, one could determine if this was a factor in the counts of waterfowl in these areas. Artificial feeding also seemed to alter species composition at the Pumphouse, and this might have been worth more systematic study. For the most part, I thought it was a great survey that was done several decades ago but still represents a classic observation-based study that gives insightful data for those looking at how waterfowl might use urban corridors to live in.
Citation:
Greer, D. M. (1982). Urban waterfowl population: Ecological evaluation of management and planning. Environmental Management, 6, 217–229. https://doi.org/10.1007/BF01866885

Flow in culverts as a potential mechanism of stream fragmentation for native and nonindigenous crayfish species

Posted on by Pen Alexandra Hunter

Background and Overview:

As the amount of urban area increases, habitat fragmentation becomes a bigger and bigger issue for many species. Crayfish are important members of aquatic ecosystems; they serve as a source of food for many other species, they are efficient detritivores, and their tunneling behavior can heavily influence the banks and beds of the streams they live in. They are also suffering from a worldwide decline in population, due primarily to a combination of habitat fragmentation and the introduction of invasive species of crayfish. This study primarily focuses on how culverts in rivers and streams affect two native populations of crayfish in Michigan, Orconectes virilis and Orconectes propinquus and their invasive counterpart, Orconectes rusticus. If O. rusticus is better able to traverse culverts than native crayfish, these barriers would allow O. rusticus to outcompete native species, further contributing to their possible extinction.

Methods:

The area of study for this project was the Carp Lake and Maple River watersheds located in Northern Michigan. Water velocity of 26 culverts at 11 different road crossings was measured and compared to water velocity ~50 meters upstream from the crossing. Velocity was measured 5mm above the stream/culvert bed to accurately reflect conditions that crayfish experience. The only species out of the three that was commonly found near the test culverts was O. propinquus, and its behavior in culverts was measured at three different flow velocities (2, 31, and 42 cm/s). A single crayfish per trial was placed at the starting location and observed for ten minutes or until it moved a meter away. Its location was marked every 30 seconds as well as the number of times the crayfish slipped as it traveled down the culvert. A “slip” refers to an involuntary movement downstream. Each crayfish was only tested once. To compare all three species to one another, a culvert in the Carp River was chosen, and the same process with O. propinquus was repeated with O. virilis, O. rusticus, and O. propinquus. Conditions were altered in the culvert with the creation of a debris dam upstream. To determine the impedance velocity, or the velocity of water at which the crayfish can no longer travel upstream, a flume was constructed in a lab using a propellor and a rubber mat to mimic conditions in a culvert.

Results:

Flow velocity in culverts was significantly higher than flow velocity in the rivers before the culvert. O. propinquus was found to alter its movements at different flow speeds. No crayfish slipped when the flow velocity was 2 cm/s, and more slipped at 42 cm/s than 31 cm/s. Smaller crayfish took longer to complete the trial at higher velocities than larger crayfish did. In order to test the theory that O. rusticus was better able to cross culverts than its native counterparts, all three crayfish species were tested in a culvert to gauge how successful they were at moving 1 meter in 10 minutes. O. rusticus and O. propinquus had fairly similar success rates and trial times, but O. virilis had a significantly harder time traversing the culverts. However, O. rusticus had an average impedance velocity that was several cm/s higher than that of the other two species. In general, larger crayfish had higher impedance velocities than smaller crayfish did.

Reflection and Critiques:

Overall, it seems like culverts will impede certain crayfish more than others, which is true of all types of aquatic animals. While it doesn’t seem like culverts will lead to the extinction of all native crayfish species, it is concerning that there are varieties of crayfish that fair significantly worse in culverts than others. Since crayfish are fairly limited in the ways they can move (by flipping their tail and crawling) they do have a harder time adapting to conditions in culverts than fish might. Most literature focuses around how freshwater fish can move through culverts, so I think that more research into how benthic organisms are affected is important. It is also difficult to say how crayfish from different parts of the US and different water conditions will be affected. I think that future research into crayfish found in different types of streams might be helpful; crayfish found in fast-flowing water might have a better chance at navigating culverts than those in wider, slower streams. One question that I have pertains to the matter of how crayfish are getting into the culverts. The study mentioned that some culverts were elevated above the river, which seems like it would pose an additional obstacle for crayfish. The study also does not account for dry culverts. Ultimately, I think it’s a good study, there are just a few gaps I think need closing.

Foster, H. R., & Keller, T. A. (2011). Flow in culverts as a potential mechanism of stream fragmentation for native and nonindigenous crayfish species. Journal of the North American Benthological Society, 30(4), 1129–1137. https://doi.org/10.1899/10-096.1 

Managing an Urban Landscape with Pollinators in Mind

Posted on by Sam Schoenberg

Overview

The article I reviewed is Enhancing pollination supply in an urban ecosystem through landscape modifications by Davis et al. (2017), published in Landscape and Urban Planning. As urban farming becomes more common, understanding how to support pollinators in cities is increasingly important. This study examines whether converting small portions of turf grass into flowering habitat could increase pollinator supply and benefit urban agriculture. The researchers used Chicago, Illinois, as their study area and focused on modeling how different strategies for increasing floral resources, such as planting flowers in city parks, residential yards, or near community gardens, would impact pollination availability. The goal was to help city planners and residents find the most effective way to support pollinators and improve crop yields in urban gardens.

Methods

The researchers first mapped the locations of urban farms, community gardens, and home food gardens using Google Earth imagery. They then collected pollinator specimens from 15 community gardens across Chicago using colored pan traps filled with a detergent solution. Traps were arranged in a 3 x 3 meter grid, spaced one meter apart, with alternating colors, and left out for one daylight cycle each month during July, August, and September 2009.

Specimens were preserved in ethanol and later identified to genus or species. Using this field data, the team validated the InVEST pollination model, which uses land cover, nesting resources, and floral resources to predict pollinator abundance. They then modeled several scenarios simulating the conversion of one to five percent of Chicago’s turf grass to pollinator-friendly flower gardens in different locations, including city parks, private yards, and areas within varying distances of community gardens, to compare how each strategy affected pollination supply across the city.

Results

The study found that augmenting floral resources can increase pollination supply in Chicago, but the most effective strategy depends on the type of urban agriculture. For home gardens, distributing flowers throughout the city was most beneficial, while concentrating flowers near community gardens and urban farms provided the greatest pollination benefits for those larger sites. The InVEST model predicted 46 percent of the variation in native bee richness, indicating that it can reliably identify areas with high or low pollination potential. The results highlight that city parks, forest preserves, and green spaces act as pollination hotspots, whereas downtown and heavily industrialized areas may have lower pollination supply.

Fig. 1. Study area (Chicago, Illinois)with inset of United States.

Fig. 2. Map of pollination supply score and location of sites used for model validation, i.e. sites where bees were collected.

Fig. 4. Effect of landscape modification scenarios on pollination supply scores.

Critiques and Reflection

While this article provides valuable insight into the role of bees in urban pollination and demonstrates how modifying turf grass can enhance pollinator supply for both residential and commercial agriculture, it has some limitations. One notable omission is the lack of consideration for other important insect orders, such as Diptera (flies) and Lepidoptera (butterflies and moths), which also play critical roles in pollination. Including these groups could provide a more complete understanding of urban pollinator communities.

The study excels in highlighting the underutilized potential of urban green spaces, particularly turf grass and ornamental plantings, and shows how thoughtful landscape modifications can provide both ecological and economic benefits. However, greater attention could be given to the use of native plantings, which not only offer nectar resources but also serve as host plants for pollinators, contributing to the restoration of urban biodiversity and supporting the life cycles of native insects.

Despite these limitations, the article provides strong empirical evidence for the importance of maximizing the ecological value of urban green spaces. It demonstrates that targeted interventions, such as converting portions of turf grass to flower gardens, can meaningfully enhance pollinator populations and improve urban agricultural productivity, making it a valuable resource for both researchers and urban planners.

Reference 

Amélie Y. Davis, Eric V. Lonsdorf, Cliff R. Shierk, Kevin C. Matteson, John R. Taylor, Sarah T. Lovell, Emily S. Minor. (2017). Enhancing pollination supply in an urban ecosystem through landscape modifications, 162, 157-166. https://doi.org/10.1016/j.landurbplan.2017.02.011

Reconciling cities with nature: Identifying local Blue-Green Infrastructure interventions for regional biodiversity enhancement.

Posted on by Ethan Horst Haneke

This study, “Reconciling cities with nature: Identifying local Blue-Green Infrastructure interventions for regional biodiversity enhancement,” was written by Donati et al. and published on August 15th, 2022. It seeks to answer the question of how we can better support regional biodiversity enhancement in cities through local Blue-Green Infrastructure (BGI) interventions. To address this, the researchers focused on how amphibian species are affected by urbanization, using the Swiss lowlands as a case study. Amphibians were chosen because they are particularly sensitive to environmental conditions compared to most other animal groups and because they depend on both terrestrial and aquatic habitats.

The researchers approached this question using habitat suitability models, high-resolution land cover data, and circuit theory models to assess biodiversity patterns in both urban and non-urban areas. In identifying the key habitat features that best support regional biodiversity enhancement, they found that stepping-stone areas allowing amphibians to move between habitats were the most important. The study highlighted features such as forest edges, wet forests, moist soils, and riparian habitats. From this, the researchers concluded that up to 15% of urban spaces could contribute to regional ecological connectivity if strategically planned and intentionally managed. Overall, the study shows that cities, if designed with biodiversity in mind, have the potential to significantly enhance ecological connectivity and support regional biodiversity.

This study is well-written and highly credible, being peer-reviewed and supported by a substantial amount of evidence. It does an excellent job of presenting its research, providing clear justification for its methodology, reasoning, and results. The focus on amphibians is particularly strong, as the authors clearly explain why this group was chosen and how it effectively demonstrates the value of biodiversity in urban contexts.

However, the study struggles somewhat with connecting its findings explicitly to the concept of BGI. BGI is often understood as engineered infrastructure—such as green roofs or rain gardens—designed to improve environmental outcomes in human-made spaces. In this study, however, BGI is framed more broadly, referring to the modification of human-used landscapes to support natural habitats and species. While this is a valid interpretation, the distinction could have been made clearer. Another limitation is the narrow applicability of the findings. Although amphibians are highly sensitive to anthropogenic impacts, results derived from their responses cannot be easily generalized to other species, such as birds or small mammals. This limits the study’s broader ecological relevance.

I personally found this study extremely interesting and eye-opening, particularly in its approach to using natural habitat features as a form of Blue-Green Infrastructure—an area of habitat management I had not previously considered. While this type of infrastructure was new to me, the results confirmed some of my assumptions about regional biodiversity enhancement in cities and also provided surprising insights. I was impressed by the depth of evidence presented, including the various mapping strategies that show cities can increase amphibian connectivity by up to 15% if key habitat features are intentionally incorporated. From this study, I have gained not only a better understanding of BGI but also an appreciation for the optimistic potential cities have to enhance biodiversity when environmental considerations are prioritized in infrastructure planning.

Overall, I found this study to be compelling and thought-provoking, proposing important ideas supported by strong data. While the study is well-executed in terms of methodology and reasoning, it does have some limitations. For instance, certain conceptual elements could have been expanded to make the findings more broadly applicable to other species and urban contexts.

The study effectively conveys its central message: cities can improve environmental conditions and support regional biodiversity if planners actively consider ecological factors in infrastructure design. Nevertheless, the work is far from exhaustive. Future research could explore how these interventions affect other species, such as birds or small mammals, and investigate practical strategies for implementing BGI in existing urban areas. Additionally, examining how cities can retrofit current infrastructure to better support biodiversity would further enhance the study’s practical relevance.

Donati, G. F. A., Bolliger, J., Psomas, A., Maurer, M., & Bach, P. M. (2022). Reconciling cities with nature: Identifying local Blue-Green Infrastructure interventions for regional biodiversity enhancement. Journal of Environmental Management, 316, 115254. https://doi.org/10.1016/j.jenvman.2022.115254

The Case of Urban Deer

Posted on by Jane Herrera

The article I have selected is called “A Review of Urban Wildlife Management from the Animal Personality Perspective: The Case of Urban Deer.” This article focuses on reviewing human-urban wildlife conflicts in Japan and North America, as well as approaches to take animals’ personalities into account to help improve urban-wildlife conflicts. In North America, the most common issues with wildlife in urbanized areas are zoonosis and wildlife-vehicle collisions. Deer are the most problem-causing. The article focuses on understanding the behavior of species and what could be a possible cause of wildlife entering urban areas and causing human-wildlife conflict. Boldness was found to be heritable, which means their ability to not be so shy is a bit genetic. According to studies cited in the article, bolder deer are more likely to enter urban areas, where they can exploit food sources and interact more frequently with humans, increasing the risk of conflict. In Japan, data showed that deer in high-conflict areas were consistently bolder than those in rural regions, suggesting a behavioral link to urban presence. The author suggests considering the genetic components of boldness when searching for control measures. In Japan, bolder deer were found to inhabit urban areas and heavily rely on humans for food, which has led to human-wildlife conflicts. Although there are benefits to continuing to build urban areas while allowing deer to coexist with humans, the idea of selecting for bolder deer, in my opinion, sounds potentially dangerous, as bolder deer could lead to serious problems. By incorporating the concept of animal personality, it opens the door to more targeted, possibly more humane strategies for managing urban wildlife.

https://www.sciencedirect.com/science/article/abs/pii/S0048969718324112

Critical Review of Crowley et al.’s “Conflict in invasive species management”

Posted on by Emy Tran

Crowley, S. L., Hinchliffe, S., & McDonald, R. A. (2017). Conflict in invasive species management. Frontiers in Ecology and the Environment, 15(3), 133–141. https://doi.org/10.1002/fee.1471

The introduction and establishment of invasive species are leading causes in global biodiversity loss. These species not only actively outcompete native and endemic species that inhabit similar environments, but can also disrupt and alter their new habitat, completely shifting the ecological dynamics that exist within all components, both biotic and abiotic, of the system. The establishment of an invasive species can cause significant damage to the population of many native species, and can even lead to local and species extinctions.

Invasive species exist within the context of their environments. This means that just because a species may be considered invasive in one area, it is not by default deemed invasive in all locations. Additionally, not all introduced or non-native species are considered invasive. In fact, a majority of non-native and introduced species are not considered invasive to their introduced range. For an introduced species to be considered invasive, it had to produce some sort of harm, generally economically, environmentally, or to human health. This harm can be realized through a multitude of ways, including damaging agricultural fields and crops. Many invasive species have been known to negatively impact agriculture and farmland, costing both farmers and governments hundreds of millions of dollars annually. Additionally, invasive species can negatively impact human health by spreading diseases. An introduced species, acting as a vector, can spread pathogens to numerous individuals, resulting in the spread of both existing diseases and potentially new illnesses. If the introduced vector species fits the criteria of an invasive species, its ability to spread disease would be greater, resulting in an increased infection rate in the human population. This would result in significant economic damage, as governments would be required to develop treatments, medications, and vaccines, and mitigate the impacts of the invasive species. 

These species also disrupt ecological systems and cause significant environmental damage. Invasive species are often extreme generalist species, meaning that they thrive in a large variety of conditions; because of this, these species frequently outcompete native species for resources such as food, nesting locations, growing spaces, etc. Invasive species are also quite efficient at reproducing and spreading, allowing them to further establish and extend their range. These species also cause economic damage this way, as governments will frequently make efforts to combat the impacts of an invasive species once it has been established. These efforts are quite economically intensive and can cost governments millions of dollars.

This study, published by Crowley et al. in 2017, evaluated the patterns in which conflicts arise within invasive species management, as well as identifying some of the more divisive management strategies, and why some of these conflicts arise initially. Sociopolitical issues are a common ignition of conflict, as management strategies have differing impacts on different individuals, communities, and cultures. Another common cause of conflict is the typically used top-down control approach, as this method often fails to recognize the more minute details of the issue; this approach also isolates the general public from the issue, as centralized authorities are making the decisions. Once a conflict has been inflicted, Crowley et al. (2017) suggest that there are two main drivers in accelerating conflict: polarization, often driving discussions to feel black and white, and escalation, which occurs as the conflict and number of involved parties grow. Escalated conflicts are self-perpetuating and can often reach a point where “winning” becomes more prominent than the initial invasive species issue. This study suggests making shifts in our existing invasive species management practices by promoting more openness in communication, placing emphasis on the context of the ecosystem, and fostering early public involvement to generate more productive management strategies. 

Figure 1. 

This study recognises its own complexities by acknowledging that each situation is entirely unique and each of the variables within these situations is unpredictable. It, however, does not offer any solutions for how to account for this variability. Instead, it offers that individuals, when engaged in conflict, tend to behave in predictable ways, allowing researchers to identify these behaviors. One potential avenue for improvement would be to explore the correlation that exists between the number of variables involved in a situation and the unpredictability of the conflict. This would allow researchers to understand more specifically how these conflicts arise and accelerate. Furthermore, this study only briefly considers actual case studies. As a result, we can only consider invasive species management strategies and their consequential conflicts, hypothetically. Due to the constraints of this study, the authors were not able to observe these species and these practices in the field. A future study may benefit by assessing these conflicts and behavior patterns firsthand, with an actively invasive population currently undergoing management practices. Overall conclusions of the study suggest that wildlife managers and officials should put more energy into proactive and anticipatory invasive species management approaches, such as monitoring programs and preventive outreach initiatives. While this would be ideal when it comes to avoiding conflict within invasive species management, as you would have to interact with fewer stakeholders, it does not account for situations in which the invasive species are already established in a new habitat. The article goes on to explain the steps that Crowley et al. (2017) identified one should take in order to minimize the risk of conflict when planning and applying invasive species management strategies; however, I propose a further study that focuses only on established invasive species populations within a given area that are managed in different ways. This study would assess how conflict arises in similar settings, and would offer a more controlled version of the study, allowing us to identify ways to minimize conflict when managing already established invasive species. 

“Black-tailed deer resource selection reveals some mechanisms behind the ‘luxury effect’ in urban wildlife”

Posted on by Aubrey Renee Hilton

Overview

The article I chose to review is “Black-tailed deer resource selection reveals some mechanisms behind the ‘luxury effect’ in urban wildlife” by Fisher et al. (2024). The study focuses on how urban deer choose where they live and feed, particularly in relation to wealthier neighborhoods. The “luxury effect” is the idea that richer areas often have more biodiversity, and this study aimed to see how that effect applies to black-tailed deer in Oak Bay, British Columbia. The authors explored whether features like big yards, green lawns, parks, and golf courses were influencing where deer spend their time.

The main goal of this study was to better understand how urban environments are providing food and shelter for deer and how that affects their movements and populations. This is important because as cities grow, interactions between people and deer are becoming more common, sometimes leading to conflicts. By figuring out what attracts deer, city planners and wildlife managers can make better decisions to balance human needs with healthy wildlife populations.

Methods

This research was conducted in Oak Bay, a wealthy neighborhood on Vancouver Island. The study area included residential neighborhoods, parks, golf courses, and the surrounding urban matrix.

Between 2018 and 2019, researchers captured 20 female black-tailed deer and fitted them with GPS collars. These collars collected location data every 13 hours, which allowed the researchers to map where the deer went throughout the year.

They then analyzed which features were most common in the locations the deer chose compared to random points across the landscape. The features they focused on were:

  • Lot size (small, medium, or large yards)
  • Vegetation greenness (NDVI, which measures how productive and healthy plants are)
  • Tree cover
  • Proximity to parks and golf courses
  • Road density

They also calculated each deer’s home range size using kernel density estimation, which gave a sense of how much space each deer used over time.

Results

The results showed strong evidence for the luxury effect. Large residential lots were the most important factor as deer were over twice as likely to be found in areas with bigger yards. These large lots also tended to have more irrigated gardens and lawns, which gave deer a steady food source.

Deer also preferred areas with greener vegetation, as well as locations near parks and golf courses. These spaces offered both food and cover. Roads, on the other hand, were avoided, which suggests that traffic is still a major deterrent.

Tree cover wasn’t a big factor in whether deer used an area. Because food and water were so easy to find in Oak Bay, the deer had very small home ranges, about a quarter of the size of deer living in wild areas, meaning that the same deer were staying in the same neighborhoods for long periods of time, which could explain why residents report seeing deer frequently.

Critique and Reflection of this Article

I found this article very interesting because it shows that urban design, particularly in wealthier areas, can actually create perfect deer habitat. The authors did a great job using GPS tracking and statistical models to clearly show how lot size and vegetation greenness are influencing deer behavior.

One limitation of the study is that it only focused on female deer, so we don’t know if males are using the landscape in the same way. It also didn’t look at how deer behavior might change across seasons, which could be important for things like fawning or mating.

References

Fisher, J. T., Fuller, H. W., Hering, A., Frey, S., & Fisher, A. C. (2024). Black-tailed deer resource selection reveals some mechanisms behind the ‘luxury effect’ in urban wildlife. Urban Ecosystems, 27, 63–74. https://doi.org/10.1007/s11252-023-01428-7

Direct and indirect effects of noise pollution alter biological communities in and near noise-exposed environments

Posted on by Sean Allen Ravenberg

Background: The point of this study was to measure the effect that noise pollution, primarily automobile generated, affected wildlife populations close to the sources of noise. While there is much documentation about direct effects of noise pollution on wildlife species that have auditory senses, especially birds and mammals, this study was designed to look at the cascading effects of noise pollution on ecosystems and food webs as a whole. Additionally, the study wanted to see if the effects of noise pollution would reach communities in quiet ecosystems separated from the noise pollution that were adjacent to the area with the exposure. The hypothesis was that noise pollution has greater systematic and cascading effects on wildlife than previously widely known.

Methods: The study measured both forest and grassland ecosystems. Six treatment sites were chosen for each ecosystem, along with six control sites for each ecosystem. All of these sites were roadless, wild sites in their respective ecosystem that had negligible noise pollution. In treatment sites, artificial recorded traffic noises were played from stationary points, and the treatment zones were split into near and far groups at the 150 meter mark from the noise source. This point was chosen because that is the distance at which the decibels of the traffic noise were registered as the same as the constant decibels of the noiseless control sites. The decibels were also measured and that data provided to confirm the treatment zones were appropriate. After a period of time, species richness and abundance data was collected in each zone for birds, grasshoppers, which represented insects capable of hearing, and odonates, which cannot hear. 

Results: The results show that a statistically significant lower amount of bird richness and abundance was recorded at the sites close to the noise, but only in forest sites. Grasshoppers and odonates showed statistically significant lower amounts of richness and abundance at the sites farther away from the noise source. The study believes that this is proof of the cascading effect of noise pollution, and claims that the results support their hypothesis. The study claims the change in bird population is responsible for the change in insect populations, and therefore the claim of cascading effects of noise pollution is proven. 

Criticisms: The study looked at result categories in a very general sense. The results contained species richness and abundance for “songbirds” as a category. I think it may be more informative to, if possible, collect more specific species data to get a sense on if these noise conditions affect all songbirds equally. While the study is focused on communities as a whole and the cascading interactions between niches, I still think more specified species information could provide a clearer picture. It’s also not clear if species abundance and richness was measured in each site beforehand, or if only theorized. If it was measured, a figure with that data does not appear to be included. I would have liked to see this experiment done with a focus on change in richness and abundance before and after treatment, rather than raw numbers on richness and abundance, as that would more clearly indicated if the treatment had an effect on the animals, rather than some other effect, or preexisting conditions of the site. I also do not know if this study is truly enough to prove that noise pollution has cascading effects. Proof of changing results for insect populations can certainly be correlated with changing results for bird populations, but I don’t know if causality can be proven. How do we know the noise itself isn’t also responsible for insect population changes?

Citation: Sensaki, Mazayuki., Kadoya, Taku., and Francis, Clinton. Direct and indirect effects of noise pollution alter biological communities in and near noise-exposed environments. NIH National Library of Medicine. 2020 Mar 25. https://pubmed.ncbi.nlm.nih.gov/32183626/

Increased access to anthropogenic food waste is linked to weight gain/Hyperglycemia in racoons

Posted on by Kira Leigh Brown

Schulte-Hostedde AI, Mazal Z, Jardine CM, Gagnon J. Enhanced access to anthropogenic food waste is related to hyperglycemia in raccoons (Procyon lotor). Conserv Physiol. 2018 Jun 13;6(1):coy026. doi: 10.1093/conphys/coy026. PMID: 29992022; PMCID: PMC6025200. https://pmc.ncbi.nlm.nih.gov/articles/PMC6025200/#coy026C24

The study makes a hypothesis that if glucose metabolism, adiposity, and body weight are affected by consumption of anthropogenic food waste, then they predict that raccoons with greater access will have higher body mass and evidence of hyperglyclemia than those with reduced access. Samples were collected from 3 different location types in Southern Ontario. Each location type had varying access to anthropogenic food: one being the Toronto Zoo grounds, with access to garbage bins, on site restaurants, etc. Moderate access sites included 3 conservation areas in Grand River Watershed, Ontario in 2012. People do not live in these areas but in close proximity residential areas. Food was only available during weekly municipal garbage collection. Low access food waste site was a farming area in Grand River Watershed, Ontario in 2012.

They limited analysis of the raccoon samples to 60 adult raccoons sampled during the months of July and August to account for seasonal variations in body weight. Their estimates of consumption were qualitative and based on potential access to food, not specific bodily measurements. More precise estimates of consumption, for example, use of stable isotopes for corn, would help determine the relative consumption of processed foods.

With the sampling of raccoons, I believe they could’ve gone further by maybe doing a longer study about from the beginning of their life or different age brackets to see if it affects different groups. It would expand the scope to examine raccoons in different seasons, not just July-August, which restricts variation in body mass. Their distribution of females to males was also highly varied in each access level. For example, there were 5 males selected for the low access area and 16 for the high access area. Because there was a higher amount sampled in the high access area, there is more variability that can be accounted for and more reliable statistical analysis. There is a slight variation in weight between females and males, which was significant in the study. There was no interaction between sex and the effect of access to anthropogenic food waste on body weight. In the future, there should be more even sample sizes to accurately measure this.

No significant difference was observed between the mean body weights of the raccoons with moderate and low access to anthropogenic food waste. In this study, they assumed that variation in body mass would be the result of differences in fat mass, but there could be differences in body size or composition instead. Their are many different ways to look at body weight distribution. Raccoons with high access to anthropogenic food waste had significantly higher glycemia levels than those with moderate and low access to anthropogenic food waste. Leptin was not significantly different among sites nor was the body mass and leptin. With other wildlife groups, such as black bear and white tail deer, leptin has had both significant and insignificant results of correlation with adiposity (fat deposition). More studies are needed to understand the impact of lepin in different wildlife groups.

Overall, there is not enough research on human activities and wildlife nutrition beyond ecological and life history consequences. There needs to be more focus on how these diets affect the endocrine and metabolic functions of these species. This may have implications for human’s food sources containing more pesticides, as well as disposal methods as waste is only increasing. It makes me wonder what solutions to wildlife access to anthropogenic food would be, especially in high access areas. Hyperglycemia and adiposity could potentially compomise the immune system of animals and increase chances of disease transmission. This could threaten the livelihood of such species. It would be interesting to look at how species are adapting to anthropogenic food sources, and what metabolic pathways are formed with unique nutrients now in their diet.

When Owls Go To Town: The Diet of Urban Barred Owls

Posted on by Lina Potas

Urban areas commonly develop in formerly biodiverse habitats, such as wetlands and valleys. This development tends to lead to an overall decrease in biodiversity, but some raptors have adapted their predation strategies to thrive in urban ecosystems. However, urban environments can also pose a higher threat to raptors through anthropogenic causes, such as window strikes and exposure to chemicals. This is especially true of anticoagulant rodenticides (ARs), which are primarily used on rodents in urban settings. The aim of this study was to determine the if exposure to ARs in barred owls stemmed from consumption of rodents with ARs in their system, or if secondary exposure from predating at bait stations caused the exposure. 

Owl pellets and prey remains were collected at nesting and roosting sites in and around Vancouver, British Columbia, Canada. The sites were found by local chapters of naturalist clubs, and playbacks were used at said sites to determine presence of barred owls. Bait stations of ARs were also scouted and their locations and distances from nests were marked. After collection, the pellets were dissected, and prey items were identified. 

The researchers found that the primary prey product of their studied owls was young adult rats. Barred owls with higher urban development surrounding their nests and roosts also had an relatively larger proportion of rats in their diets. Because rats are one of the primary targets of ARs, barred owls are subsequently at risk for posioning from secondary exposure to ARs. 

This study does state that barred owl in urban areas in British Columbia are at risk for secondary AR exposure, it never discusses if there is a risk for primary exposure. Primary exposure is mentioned in the abstract and background information, but not in the results, so readers do not know if this is also a reason for concentrations of ARs in barred owls. Furthermore, the researchers do not discuss how these results could apply to other urban areas. Doing so might be considered speculation, but I would like to know more about how we can use their results more broadly. I also would’ve liked to know more about black bait stations used to deploy ARs, so I could know specifically how they are affecting barred owl predation efforts. 

Hindmarch, S. and Elliot, J.E. When Owls Go To Town: The Diet of Urban Barred Owls. Journal of Raptor Research 49 (1): 66-74. https://doi.org/10.3356/jrr-14-00012.1