Authored by Emma Phillips and Katie Black

You may have noticed that our observation list is dominated by insects lately, with Common Eastern Bumble Bee being our most observed species. You might be asking, “Isn’t this project primarily targeting reptiles?”. While the answer is yes, we've also been recording conspicuous insects that we encounter on roads. We've made some interesting observations related to pollinators and roadside habitats. Throughout the field season, we’ve documented a high abundance of pollinator species both active in roadside vegetation and killed on roads due to vehicle collisions.

Despite evidence of vehicle-induced pollinator mortality, roadsides can provide a variety of benefits to pollinators, and there’s a growing interest in roadside pollinator projects (e.g., Lanark County, 2021). Our natural landscapes have changed significantly due to human development, and roadside vegetation offers a food source through the nectar and pollen of wildflowers, important reproductive host plants for butterfly and moth species, and breeding, nesting, and overwintering habitat (Hopwood, 2013). Roadside habitats can also help pollinators move through landscapes by linking fragmented habitats (Hopwood et al., 2015). Unfortunately, not all roadsides benefit pollinators (Hopwood, 2013). Roadsides managed with high-frequency mowing, broadcast spraying of herbicides, and planted with non-native grasses support a much lower diversity of pollinators and directly cause population decline (Hopwood, 2023). Our observations reflect such effects, with higher pollinator observations at sites dominated by native vegetation. These roadside vegetation management practices are used to achieve three main goals: decrease the risk of wildlife-vehicle collisions, prevent the spread of invasive and noxious weeds, and prevent erosion (Hopwood et al., 2015). So, how do we change our current efforts to focus on pollinator conservation while still achieving our goals and remaining cost-efficient?

The first step is re-establishing and promoting native vegetation (Storey et al., 2020). Roadsides with a high diversity of native vegetation have been found to support 35% more bee species by providing optimal foraging and nesting habitat for pollinators throughout the growing season (Hopwood, 2003). Once established, a high diversity of native vegetation also helps prevent erosion, reduces noxious/invasive plant abundance, reduces stormwater runoff, and causes fewer driver visibility issues (Storey et al., 2020). The second step is to modify the timing and frequency of mowing completed during the growing season (Hopwood, 2013). High-frequency mowing is a common practice, as we have observed at our survey sites, with mowing occurring at least four times already this year. Studies have found that mowing once in the early spring or late autumn, selective mowing of unwanted plant species, or eliminating mowing can increase the diversity of native species while reducing runoff, erosion, and the spread of invasive species (Storey et al., 2020). Lastly, herbicide use can be modified to target and control specific unwanted species in replacement of broadcast spraying (Storey et al., 2020). This method ensures that target species are treated and limits the adverse effects on the surrounding environment (Storey et al., 2020).

Implementing roadside vegetation management practices that benefit pollinators can significantly improve monetary savings for road agencies (Storey et al., 2020). Such savings are derived from decreased human effort, equipment, and other resources, along with increasing the value of ecosystem services associated with pollinator abundance and diversity (Storey et al., 2020). A study completed by the Florida Department of Transportation revealed that a reduced mowing frequency had the potential to save 30% ($1.2 million) of their annual budget, and the ecosystem services provided by sustainable management could be valued at $0.5-1.5 billion annually (Storey et al., 2020). Similarly, the Georgia Department of Transportation implemented reduced mowing due to budgetary constraints, with the cost savings being $10.95 million the following year (Storey et al., 2020). These studies demonstrate the potential economic gain of adopting a pollinator-friendly roadside management plan.

While adopting such an approach seems to bring many benefits, there is a concern that enhancing roadside habitat may increase pollinator mortality due to vehicle collisions. Our observations to date include 538 dead pollinators caused by presumed vehicle collisions, including 266 bees and 49 butterflies. Anecdotally, we seem to be finding more dead pollinators in road areas that have ideal roadside habitat. These observations are concerning, especially since our transects only cover a total of 2.6 km of County roads, and there were likely many individuals missed. However, research shows that roadside vegetation management with pollinators in mind can mitigate road mortality and increase species richness and abundance, and further considerations can be made to minimize collisions (Daniel-Ferreira et al., 2022; Skorka et al., 2013). Overall, increased diversity of native flowering plants is positively correlated to increased pollinator species richness and abundance and a comparatively decreased number of individuals crossing the road (Storey et al., 2013). In other terms, the larger the pollinator population, the lower the impact of road mortality, meaning better-suited roadside habitat will mitigate the potential effects of population decline due to vehicle collisions (Storey et al., 2013).

Restoring and widening road shoulder habitat by even 1 meter can drastically increase the number of pollinators at a site (Skorka et al., 2013). In areas with narrower habitat, there is not enough habitat to support high pollinator populations, causing road mortality to be a more significant risk in overall population decline as individual deaths pose a more significant impact (Skorka et al., 2013). Areas where roadside habitat can be expanded should therefore be a focus for pollinator conservation efforts (Skorka et al., 2013).

In combination with roadside habitat width, traffic intensity and road width influence pollinator roadkill (Daniel-Ferreira et al., 2022; Skorka et al., 2013). For bumble bees, high traffic intensity can double road mortality compared to less travelled roads (Daniel-Ferreira et al., 2022). The rate of butterfly mortality in the same scenario is not as significant, but when combined with a larger road width where butterflies need to travel longer distances, there can be a more substantial increase (Skorka et al., 2013). Due to these factors, it is recommended that conservation efforts for roadside habitat focus on roads with lower traffic volumes, narrower roads, and lower speed limits (Skorka et al., 2013).

Landscape features surrounding the road should also be considered when prioritizing pollinator conservation efforts (Daniel-Ferreira et al., 2022; Skorka et al., 2013). Having native grasslands and meadows in close vicinity to roads is significant, as it provides additional habitat and refuge for pollinators, increasing overall populations both on roadsides and within the broader landscape (Daniel-Ferreira et al., 2022; Skorka et al., 2013). When this habitat is available, populations of pollinators such as butterflies and bumble bees can boom and are more likely to avoid roads (Daniel-Ferreira et al., 2022; Skorka et al., 2013). In contrast, pollinator road mortality can be higher along roads next to forests as wooded areas do not typically provide the type of habitat that pollinators prefer (Daniel-Ferreira et al., 2022; Skorka et al., 2013). In this scenario, pollinators may be more likely to travel via open roadways, increasing risk of vehicle collision (Skorka et al., 2013). Restoration of roadside habitat for pollinators in forested areas may therefore cause more harm than good, so future efforts should focus on roadsides adjacent to grassland and meadow habitat (Skorka et al., 2013).

Human settlements, especially in rural or agricultural areas, have also proved to be beneficial landscape features for successful pollinator roadside habitats (Daniel-Ferreira et al., 2022; Skorka et al., 2013). Farmland and residential areas provide an opportunity for many flowering crops and gardens, which increases pollinator habitat away from roadsides (Skorka et al., 2013). This decreases the need for pollinators to travel across roads when foraging and nesting (Daniel-Ferreira et al., 2022; Skorka et al., 2013).

This is where you can help! When planting new gardens, consider designing spaces that are pollinator-friendly, including a high diversity of native flowering vegetation. For more information, visit this website, and BEE friendly to our important insect friends: https://www.toronto.ca/services-payments/water-environment/live-green-toronto/help-native-bees-pollinators/#:~:text=Provide%20continuous%20bloom%3A%20Pollinators%20need,to%20find%20and%20collect%20pollen.

References

Daniel-Ferreira, J., Berggren, A., Bommarco, R., Wissman, J., Ockinger, E. (2022).
Bumblebee queen mortality song roads increase with traffic. Biological Conservation, 272. https://doi.org/10.1016/j.biocon.2022.109643

Hopwood, J. L. (2013). Roadsides as Habitat for Pollinators: Management to Support Bees
and Butterflies. Proceedings of the 2013 International Conference on Ecology andTransportation. Retrieved from: https://www.researchgate.net/profile/Jennifer-Hopwood/publication/286066214_ROADSIDES_AS_HABITAT_FOR_POLLINATORS_MANAGEMENT_TO_SUPPORT_BEES_AND_BUTTERFLIES/links/5665c80308ae418a786f2b72/ROADSIDES-AS-HABITAT-FOR-POLLINATORS-MANAGEMENT-TO-SUPPORT-BEES-AND-BUTTERFLIES.pdf

Hopwood, J., Black, S. H., Lee-Mader, E., Charlap, A., Preston, R., Mozumder, K., & Fleury,
S. (2015). Literature ReviewL Pollinator Habitat Enhancement and Best Management Practices in Highway Rights-of-Way [PDF]. Federal Highway Administration. Retrieved from https://xerces.org/sites/default/files/2018-05/15-055_01_pollinators_BMPs_in_highway_ROW.pdf

Lanark County. 2021. Media Release: Roadside Pollinator Habitat Restoration Pilot Project Underway. Posted on Monday, May 24, 2021. Retrieved from: https://www.lanarkcounty.ca/en/news/media-release-roadside-pollinator-habitat-restoration-pilot-project-underway.aspx

Skora, P., Lenda, M., Moron, D., Kalarus, K., & Tryjanowski, P. (2013). Factors affecting
road mortality and the suitability of road verges of butterflies. Biological Conservation, 159: 148-157.

Storey, B., Das, S., McFalls, J., Moran, R. A., & Dadashova, B. (2020). Comparison of Cost,
Safety, and Environmental Benefits of Routine Mowing and Managed Succession of Roadside Vegetation. Transportation Research Board of the National Academics of Sciences, Engineering, and Medicine. Printed Document. Retrieved from: https://onlinepubs.trb.org/Onlinepubs/nchrp/docs/NCHRP14-40FinalReport.pdf

Authored by Katie Black and Clay Shearer

We’d like to thank Fred Schueler, Dave Seburn, and Sheldon Lambert for sharing their thoughts on the topics addressed in this post.

During our surveys, we’re accustomed to seeing routine roadside maintenance including vegetation management and grading of road shoulders. Vegetation management includes using a mower or chainsaw to improve motorist visibility of roads, ditches, road signs, and guardrails. It also includes applying herbicide such as glyphosate, which is the active ingredient in Roundup. Road grading involves levelling and re-shaping the unsealed shoulders with a grader that’s towed behind a vehicle.

Roadside maintenance can interact with wildlife in several different ways, some of which may be beneficial, though overall are likely to be negative. Mowing can directly injure and kill animals such as amphibians and snakes (Danby et al., 2016), but we’ve also found that milksnakes like to hide under the grass thatch left behind from mowing: https://www.inaturalist.org/observations/170205911

Suppression of vegetation through herbicide use may create turtle nesting sites by exposing substrate and reducing shading (F. Schueler, pers. comm.). However, the spraying of herbicides could potentially harm turtle nests along roadsides, though there’s minimal research on this. De Solla et al. (2011) demonstrated that typical field application rates of herbicide for corn production in Ontario may not be a major threat to Snapping Turtle hatchling success. In contrast, Mendonça et al. (2023) studied the effects of glyphosate on the Amazon turtle using commercial formulation measurements and found that it interfered with eggshell chemical composition, reducing moisture content, crude protein, and increasing ethereal extract. These effects could cause alterations in the mobilization of water and nutrients essential for proper development of the turtle embryo.

Roadside grading may also interact with turtle nests as it usually occurs throughout the nesting and incubation period (i.e., May through September). Grading may occur above nest depth but can lead to further burying and/or compaction of nests (Marchand & Litvaitis, 2004). Since nests are already belowground, it’s not clear if this is harmful. If grading does occur at nest level, it could cause direct damage to nests, and this may be of particular concern for turtle species that excavate shallower nests. We and the local experts we’ve consulted have never seen a turtle nest that was obviously destroyed by grading, but we suspect it happens. Further studies are needed to better understand the effect of roadside grading on turtle nests. Potential mitigation includes limiting grading to outside of the nesting and incubation period, but this may be challenging for municipalities given the seasonal constraints associated with grading. Another option is to pave road shoulders; this would remove nesting habitat, but considering the dangers associated with nesting along roads (e.g., adult and hatchling road mortality), this may be the best option while also reducing maintenance needs (D. Seburn, pers. comm.).

In addition to vegetation management and roadside grading, guardrail work can impact animals that use roadside habitats. The replacement of guardrails during the turtle nesting and incubation period can directly disturb nests (S. Lambert, pers. comm). The extensive use of road salts in de-icing can also be harmful, particularly to aquatic and semi-aquatic organisms (Arnott et al., 2020). For example, high chloride concentrations in roadside ditches and wetlands can reduce embryonic and larval survival of amphibians (Karraker et al., 2008) and alter amphibian community structure by excluding salt intolerant species (Collins & Russell, 2009).

Ultimately, roadsides can create artificial habitat for a variety of species, but routine maintenance can cause negative effects in the absence of mitigation. There are several helpful resources available that provide recommendations for best management practices, including Turtle Nests - Road Shoulder Maintenance Management Best Practices: A Guide for Municipalities (Berman, 2017) and Best Management Practices for Mitigating the Effects of Roads on Amphibian and Reptile Species at Risk in Ontario (OMNRF, 2016).

Thanks for stopping by!

References:

Arnott, S.E., Celis-Salgado, M.P., Valleau, R.E., DeSellas, A.M., Paterson, A.M., Yan, N.D., Smol, J.P., and Rusak, J.A. 2020. Road salt impacts freshwater zooplankton at concentrations below current water quality guidelines. Environmental Science & Technology, 54: 9398–9407.

Berman, L. 2017. Turtle nests-road shoulder maintenance best management practices: A Guide for Municipalities. Available online at: https://centrehastings.civicweb.net/document/30761/TURTLE-NESTS-ROAD-SHOULDER-MAINTENANCE-BEST-MANAGE.pdf?handle=E8A6A26CA3F240A797C08C15BF6DE949 [Accessed 1AD].

Collins, S.J., and Russell, R.W. 2009. Toxicity of road salt to Nova Scotia amphibians. Environmental Pollution, 157(1): 320-324.

Danby, R., Karch, M., Shearer, C., Schueler, F., and Smith, C. 2016. Highway 401 (Gananoque to Brockville) Species at Risk road ecology project 2014-2016. Prepared for the Ontario Ministry of Natural Resources and Forestry Species at Risk Stewardship Fund (Project #1-14-A2A). Algonquin to Adirondacks Collaborative, Landsdowne, ON, and Ontario Road Ecology Group, Toronto, ON.

De Solla, S.R., Martin, P.A., and Mikoda, P. 2011. Toxicity of pesticide and fertilizer mixtures simulating corn production to eggs of snapping turtles (Chelydra serpentina). Science of the Total Environment, 409(20): 4306-4311.

Karraker, N.E., Gibbs, J.P., and Vonesh, J.R. 2008. Impacts of road deicing salt on the demography of vernal pool-breeding amphibians. Ecological Applications, 18(3): 724-734.

Mendonça, J.D., de Almeida, J.C.N, Lucélia Gonçalves Vieira, L.G., Hirano, L.Q.L, Santos, A.L.Q, Andrade, D.V., Malafaia, G., de Oliveira, R.J., and Beletti, M.E. 2023. Mutagenicity, hepatotoxicity, and neurotoxicity of glyphosate and fipronil commercial formulations in Amazon turtles neonates (Podocnemis expansa). Science of the Total Environment, 898: 165529.

Marchand, M.N., and Litvaitis, J.A. 2004. Effects of landscape composition, habitat features, and nest distribution on predation rates of simulated turtle nests. Biological Conservation, 117(3): 243-251.
Ontario Ministry of Natural Resources and Forestry. 2016. Best Management Practices for Mitigating the Effects of Roads on Amphibians and Reptile Species at Risk in Ontario. Queen’s Printer for Ontario. 112 pp.

Authored by Clay Shearer and Katie Black

June is the peak of the turtle nesting season in our area. Now that we're half-way through August, we can reflect on our turtle nesting observations. During nesting season, it is common to see turtles nesting along the roadside, but also shallow pits with scattered egg fragments indicative of nests lost to predators.

We’ve been recording depredated turtle nests during our road surveys*, with the most significant cluster located along County Road 20 where it crosses Kemptville Creek in North Grenville. Here we’ve counted over 30 depredated nests, some of which were laid last year, but most were from 2023. Most nests were found along an open, sandy bank of Kemptville Creek which appears to be used as an access point for anglers and non-motorized watercraft. Other nests at this site were found along the gravel road shoulders, including under the guardrails.

Fred Schueler and Aleta Karstad of Fragile Inheritance recommended this site for our study based on their numerous observations of nesting Snapping Turtles. Running the Bishop’s Mills Natural History Centre just down the road, they have a great deal of turtle nesting data for the area dating back to the early 1990s. Our turtle observations for this site combined with those from Fragile Inheritance and iNaturalist show that this area provides habitat for a diversity of turtle species including Snapping Turtle, Eastern Musk Turtle, Midland Painted Turtle, Northern Map Turtle, and Blanding’s Turtle.

Raccoons are a common predator of turtle nests in Ontario. At the Kemptville Creek site, we’ve seen raccoon prints and scat along the road shoulder and along the sandy bank. Fragile Inheritance’s database has numerous instances of raccoons at the Kemptville Creek bridge during peak nesting time. We also thought we saw evidence of digging by raccoons, which was later confirmed by Fred and Aleta. They observed a young raccoon digging the exact holes that we saw right next to two freshly depredated Snapping Turtle nests.

So, what can be done to protect turtle nests from hungry raccoons and other predators? Individual wooden nest protectors are an option, but this relies on the installer to be present at the right moment after nest construction, but also before depredation. As we have seen, this can be a small window of time when dealing with raccoons, sometimes less than 48 hours. Another possibility for areas known to have a high concentration of nests would be installing an electric fence around the nesting area that allows turtles to enter and exit but prevents raccoon entry (Streeting et al., 2023). This method is less practical for areas where nests are spaced further apart.

*A note about counting depredated nests: at the start of the study, we would bury depredated nests to avoid double-counting them. However, this led to animals digging up the nest a second time. It's unknown whether this was due to the smell of the remaining egg fragments, or geosmin, the chemical made by microbes that creates the smell of freshly dug soil that can attract predators (Geller, 2015; Buzuleciu et al., 2016). Also, the egg fragments that we buried that were not dug up a second time were often exposed after a heavy rain. We now collect and discard the egg fragments to avoid double counting and to prevent re-attracting predators.

Please share your thoughts below!

References

Buzuleciu, S. A., Crane, D. P., & Parker, S. L. (2016). Scent of disinterred soil as an olfactory cue used by raccoons to locate nests of diamond-backed terrapins (Malaclemys terrapin). Herpetological Conservation and Biology, 11(3), 539-551.

Geller, G. (2015). A test of substrate sweeping as a strategy to reduce raccoon predation of freshwater turtle nests, with insight from supplemental artificial nests. Chelonian Conservation and Biology, 14(1), DOI: https://www.researchgate.net/publication/281129702_A_Test_of_Substrate_Sweeping_as_a_Strategy_to_Reduce_Raccoon_Predation_of_Freshwater_Turtle_Nests_with_Insights_from_Supplemental_Artificial_Nests

Authored by Clay Shearer and Katie Black

Welcome! Thank you very much for supporting our project. At least once every two weeks, come here to find posts of field stories and observations that we find to be particularly noteworthy. If you have anything to contribute, we'd love to hear from you.

Our field work started in early May and will continue until October 2023. We are recording observations of wildlife, especially turtles, on County roads and adjacent habitat in Leeds and Grenville. A subsample of 12 locations on County roads were chosen for field surveys based on their predicted mortality risk: low, medium, or high. The high risk sites had known turtle occurrences and suitable habitat, the medium risk sites had suitable habitat but no record of turtle occurrences, and the low risk sites had neither. We have four road transects associated with each risk level; half are in Leeds and half are in Grenville to capture landscape variation between the two regions. Each transect is 200 m in length, which we survey twice each week on foot. We also include incidental and volunteer observations from County roads in Leeds and Grenville. These important contributions have been made by people local to the transect areas and members of this iNaturalist project. We would like to thank all of you! Observations submitted to iNaturalist will be used to refine our predictions of road mortality risk across the County, which will help us develop location- and risk-specific mitigation measures.

One of our transect sites is located at a bridge crossing on County Road 42 in Newboro, where the road spans a lock associated with the Rideau Canal system. We originally thought this site had a medium risk of road mortality because it was not affiliated with turtle occurrence records but appeared to be associated with suitable turtle habitat. Despite an absence of turtle records, we typically observe Northern Map Turtles in the canal. This species is listed as Special Concern under the Endangered Species Act. We have observed up to seven Northern Map Turtles basking on the same granitic boulder at once. It did not take us long to notice that many of these turtles had shell abnormalities. After seeing multiple motorboats pass through the canal and right by the turtles, we wondered if these could be attributed to propeller injuries. Please follow this link to see images of these turtles: https://www.inaturalist.org/observations/161471335

We set out to study wildlife-vehicle collisions on roads, but this observation got us thinking about watercraft-turtle collisions. Both pose significant threats to freshwater turtles, while the latter is sorely understudied. Northern Map Turtles are particularly susceptible to collisions with watercraft, and females may be at greater risk because they are typically twice the size of males and tend to venture farther from shore (Bulte et al., 2010). In a study conducted on the Trent–Severn Waterway, it was found that 28.6% of female Northern Map Turtles exhibited propeller injuries, with males showing 12.8% (Bennett et al., 2014). When motorboat collisions occur, chance of turtle survival is very low. Bulte et al. (2010) found that Northern Map Turtles hit by boats in nearby Lake Opinicon and the St. Lawrence River near Thousand Islands National Park have almost a zero percent chance of survival, with the odds being lower for females.

Vehicles and boats alike can negatively impact turtles, and while our study is focused on mitigating collisions with vehicles, we think that some mitigation measures typically used for roads could also be applied to waterways. For instance, perhaps a buoy with a turtle crossing sign and limiting boat speed would reduce risk of watercraft collisions with turtles. Public outreach to promote awareness would be beneficial, especially considering that the public is more familiar with turtle mitigation on roads than on waterways.

Please leave a comment below!

References

Bulté, G., M. A. Carriere, and G. Blouin-Demers. 2010. Impact of recreational power boating on two populations of northern map turtles (Graptemys geographica). Aquatic Conservation: Marine and Freshwater Ecosystems, 20(1): 31-38. https://doi.org/10.1002/aqc.1063

Bennett, A. M., and J. D. Litzgus. 2014. Injury rates of freshwater turtles on a recreational waterway in Ontario, Canada. Journal of Herpetology, 48(2): 262-266. http://dx.doi.org/10.1670/12-161