Author: Alexandria Helena Lupton

A Critical Review of: Least-cost path analysis for urban greenways planning: A test with moths and birds across two habitats and two cities

Posted on by Alexandria Helena Lupton

Habitat fragmentation and destruction is one of the primary drivers of extinction and species’ endangerment in today’s ever-evolving world. With impervious surfaces becoming very prevalent as urban areas continue to grow and sprawl, animals are left without safe passageways within urban settings. One solution that has gained traction and support are ecological corridors. Ecological corridors or wildlife corridors are physical green spaces that are protected from surrounding human development that allow for a natural passageway between dangerous environments such as highways, cities, and other development.

One study in France in 2020 wanted to test the efficacy of these corridors through various least-cost paths (LCPs) that both reduce cost of development of a corridor with success-rate of a well-used corridor by wildlife. This study was done primarily using mark-release-recapture (MRR) methods for moths, and using audio playback of calls for passerines to get a broader scope of data for determining future landscape planning decisions for wildlife corridors.

The study area for this research consisted of two medium-sized cities within France (Rennes and Lens). Both sites were comprised of a rough half and half split between “artificialized surfaces” (man-made structures, developments) and urban green spaces (parks, yards, large medians). The study groups of moths and passerines were carefully picked for both their vulnerability to urban development and their previously noted behaviors with movement across urban settings.

After determining the habitat data for each experimental group, the study modeled a few predictions for effective corridors using LCP models in ArcGIS. In these models, they cross-referenced high density habitats with rough resistance values of the animals to travel/move near specific land types. 

The mark-release-recapture for the moth study group was conducted in 2015 in Lens and 2016 in Rennes, with results primarily relying on the amount of individuals recaptured within specific areas across the city. Additionally, each recapture was replicated three times per area for accuracy.

Then the playback recalls for the passerine study group were conducted from April to May in Lens and 2016 in Rennes. These trials were to test response behavior of passerines to specific areas based on development. The variables for this group were testing how far an individual would fly based on the artificial calls and their response time to the call. 

The data was collected into mixed models to contextualize the connectivity in context with the variables tested of moths and birds to the different levels of urban development. The amount of connectivity was categorized into two different sections, highly connecting contexts (HCCs like green spaces and less developed areas) and less connecting contexts (LCCs like buildings, impervious surfaces, and more developed areas). 

For the moth recapture group, among marked individuals, 77% of them were recaptured in HCC areas and and 23% were recaptured in LCC areas.

For the passerine callback group, 66% of birds had a positive response (significant movement speed and distance moved). Overall, in the HCC areas, it was observed that there was significantly higher movement distance (~84m) and speed on average than in LCC areas (~46m). Additionally, there was a longer delay in response from passerines within LCC areas than in HCC areas. 

The larger results show that moths were 4 times more likely to be recaptured in HCC than in LCC areas. However, the study admits that some likely explanations for this could have been due to the presence of light pollution and habitat fragmentation within the cities when compared to natural habitats. This supported the original hypothesis that natural areas do help to facilitate moth movement and dispersal. Similarly, passerines did travel significantly more in HCC than LCC areas. Also, since passerines reacted quicker in HCC areas, it suggests that they do react quicker with territorial behaviors in more natural settings. This shows that urban matrixes could be contributing to an overall slowing down of both movement and responses from local wildlife. 

For future research, the study suggests that shifting to more small mammals studies in a similar habitat connectivity context could be useful for aggregating data and drawing more connections for urban planners. Additionally, this study included many species from both moths and passerines, and still seeing large trends towards more movement and faster responses in natural settings, showing that this effect is not specialized towards specific species. However they also point out that every single city is going to have a slightly different matrix of developed to non-developed areas, hampering the ability for a blanket-approach to be possible. In future studies and urban planning, specialized research and approaches need to be taken in context to the city they are taking place in. Only broader knowledge of impacted behaviors and movements can be applied across multiple areas for baseline understanding to be built upon.

Balbi, M., Croci, S., Petit, E., Butet, A., Georges, R., Madec, L., Caudal, J. & Ernoult, A., (2020, November 24). Least-cost path analysis for urban greenways planning: A test with moths and birds across two habitats and two cities. Journal of Applied Ecology, Volume 58, Issue 3, Pages 632-643, https://doi.org/10.1111/1365-2664.13800 

A Critical Review of: “Are British urban foxes (Vulpes vulpes) “bold”? The importance of understanding human-wildlife interactions in urban areas

Posted on by Alexandria Helena Lupton

The process and expansion of urbanization is becoming an increasingly prevalent issue across the globe. Among the list of problems increased human-wildlife interactions creates, interactions with carnivores are one of the more serious. Some groups of carnivores, such as coyotes and red foxes, have begun to adapt their behaviors to better coexist with humans, whether that be through self-domestication or a more simple symbiotic relationship. However, the long term consequences and cascading effects of these new behaviors is unclear.

One British study published in 2020 focused on the red fox (Vulpes vulpes) and their potential changes in behaviors of neophobia (fear of new things, or level of curiosity) and overall wariness of new and changing environments. The study notes that many British news articles and journals have discussed public discourse with the increase in red fox populations within their yards and common spaces, describing the canids as “bold.” However, they also explain that by continuing stereotypes of foxes being “sly” and “cunning,” it completely disregards the personalities that foxes (and many other animals) display, and causes more public issues in the long run. 

While this study is highly qualitative and variable based on scientists’ opinions, the methods for the study created very quantitative and concrete results. The mapping of the study area for six urban fox groups was tested through both radio-tracking and camera traps to identify the foxes’ territories and boundaries.

After firm boundaries for each group of foxes was determined, many smaller experimental areas were created in randomly selected gardens/yards within sparsely populated suburban areas. These areas were small circles cut into the lawns, divided into 4 quadrants: quadrant 3 facing the house, quadrant 1 being closest to the entry of the lawn (for the foxes), and quadrants 2 and 4 facing the sides of the yard. 

While results were conducted in batches to test seasonality (late November-early December 2014 and May 2015), the seasonality ended up not impacting the overall data (null). The recording equipment was to help provide identification of individual foxes (for personality and behavioral details) and for testing how curious foxes were based on the quadrants and areas they explored, in addition to a new or foreign object. To test wariness behaviors (“a response to a potentially threatening stimulus”), the study used garden twine that had been soaked in wolf urine. Figure 6 shows the placement of the foreign object in orange (neophobia test), and the placement of the urine soaked twine in blue.

The results were determined by how quickly the foxes would get to the food hidden with the new object, overcoming their neophobia, and the wariness related to the urine-soaked twine (all behaviors before and after this process were noted as well). The behaviors were described by specific standards and parameters as shown in table 2:

The overall results from both seasons of the study, with 2,127 visits from foxes, the classified “dominant” foxes were shown to have made more visits to the circle and quadrants than “subordinate” foxes. However, the dominant foxes would not explore nearly as much as subordinate foxes, leading to the conclusion that there is a strong relation between personality and neophobia and wariness. Additionally, while most of the visits were from foxes that were alone, these solitary fox visits also showed significantly more present behaviors of both neophobia and wariness, in comparison to foxes who visited the sites in groups. 

This data shows that the increased fox presence (or “nuisance” as depicted by public articles), is possibly being artificially selected for because of the availability of food, as many as 1 in 7 people put food out for the foxes. While the small complexities and details of fox personality and behavior were unable to be explored in this study due to scope and time, it opens the way for more understanding between human and fox populations. Especially in a time when more and more wildlife habitat is being encroached upon, finding ways to mesh big social and personal differences between species will become increasingly necessary. Conclusively, more research needs to be done on the intricate communities and the entire social network that occurs both with and without human intervention/interaction. This way, we can both reduce human-wildlife interactions and reduce the negativity explored by preconceived expectations and notions of various wildlife species.

Padovani, R., Shi, Z., & Harris, S. (2020, December 26). Are British urban foxes (Vulpes vulpes) “bold”? The importance of understanding human-wildlife interactions in urban areas. Ecology and Evolution, Volume 11, Issue 2, Pages 835-851, https://doi.org/10.1002/ece3.7087