Camp Fire Program

In Wildlife Conservation

Campfire Fund SUNY College of Environmental Science and Forestry New York Department of Environmental Conservation

Research: When Vehicles and Mammals Collide

An elk crossing the road while cars wait. Photo by Noel Reynolds.

When humans and wildlife attempt to share the road, it doesn’t always bode well for the mammals. To date, the impact of collisions between vehicles and animals has been calculated simply by relying on the number of carcasses observed on the road. A study published in a recent issue ofLandscape and Urban Planning offers a clearer impact of vehicle mortality on mammals for the past 50 years and suggests clues to ensure the future of North American mammals and humans.

Using a novel approach, the multi-institution team of scientists analyzed a comprehensive review of 421 telemetry-based studies that monitored 34,798 individuals across 66 species. Radio-telemetry allows researchers to monitor an individual animal via handheld radio signal tracking or remotely downloaded GPS locations. If an animal is killed, researchers are able to determine the specific cause. By knowing the different mortality sources of individual animals within a population, a proportion of mortality from vehicle collisions can be derived, as opposed to observation alone.

“Vehicle mortality is not novel to mammal population, but the rate at which it occurs is increasing,” said Dr. Jerrold Belant, Camp Fire Conservation Fund Professor in the SUNY College of Environmental Science and Forestry’s (ESF) Department of Environmental and Forest Biology, and one of the study’s authors. “Over the 52-year study period, vehicle mortality increased four-fold for North American mammals, from three percent in the first decade (1960s) to 12 percent by the last decade (2010s). Not surprisingly, not all species are impacted in the same manner.”

Mammals with omnivorous diets suffered greater vehicle mortality than carnivores or herbivores.

“The greater foraging potential near roads for omnivores compared to herbivores may result in their increased use of roadside environments and lead to greater wildlife mortality via vehicle collisions,” said Dr. Jacob Hill, research scientist from ESF. “As dietary flexibility is positively associated with mammal adaptability to human-modified areas, omnivores may be more likely to inhabit areas where roads are present, also contributing to higher vehicle mortality rates.”

The increased mortality caused by vehicles has the potential to impact overall population dynamics.

“Individuals killed by vehicles often have better body condition than those killed by predators,” Hill said. “As body condition is often linked with fertility, vehicle mortality may alter population dynamics by removing individuals with the highest reproductive potential.”

The study recommends management techniques, with the goal of reducing the availability of food in roadside environments.

“Habitat management or removal of carrion may decrease risk of vehicle collisions,” Hill said. “As human developments and road networks continue to expand, the importance of understanding vehicle mortality risks is exceedingly necessary for both conservation of North American mammals and human counterparts alike.”

Dr. Travis DeVault, associate director of research, at the University of Georgia’s Savannah River Ecology Laboratory also contributed to this research.

Read the full journal article at: https://doi.org/10.1016/j.landurbplan.2020.103746

A Big Idea for Small Mammal Diversity Modeling

This story was published by the National Ecological Observatory Network.

https://www.neonscience.org/impact/observatory-blog/big-idea-small-mammal-diversity-modeling

You can’t see chipmunks, mice and voles from an airplane—especially when they are scampering beneath the forest canopy or burrowing in the ground. But a new modeling approach could allow researchers to use remote sensing lidar data to predict small mammal biodiversity based on the structure of vegetation in an area.

The study was led by Sarah Schooler, now a Ph.D. candidate at State University of New York (SUNY)–Syracuse, and Harold Zald of the Humboldt State University Department of Forestry and Wildland Resources. Sarah’s experience working as a seasonal NEON field botanist inspired her to find innovative ways to use data from the NEON project. Lidar Prediction of Small Mammal Diversity in Wisconsin, published in Remote Sensing, explores how measurements of vegetation structure created with lidar data could be used to predict the diversity of small mammal communities.

A Lidar-based Predictive Model for Small Mammal Diversity

Sarah’s inspiration for the study came from her work with the NEON project and her experiences with her mentor and professor at Humboldt State, Dr. Harold Zald. His advanced remote sensing class introduced her to remote sensing methods and gave her the skills she needed to put the data to work.

Vegetation structure is known to be correlated with diversity for many taxa of animals, including birds, mammals and insects. A single forest can provide a range of habitats, from areas with dense canopy cover and a relatively open understory to areas with a thick understory of brush, shrubs and a variety of herbaceous plants. Different animal species prefer different types of habitats. Most models predict that areas with more diverse vegetation structure will also support more diverse animal communities.

Traditionally, vegetation structure has been evaluated with painstaking fieldwork. Lidar (Light Detection And Ranging) is a remote sensing system that uses pulses of light to measure vegetation height and 3D structure. The NEON project uses lidar data collected using the Airborne Observation Platforms (AOPs) to construct 3D models of vegetation structure at NEON terrestrial field sites. Using lidar, researchers can quickly gather information about canopy height and complexity, canopy cover, and understory complexity over very large areas.

Sarah wanted to find out whether lidar data could be used to predict small mammal diversity at the NEON field sites in Wisconsin. Using small mammal counts and lidar data from the NEON Data Portal, she found that lidar-derived variables (including structural diversity, canopy cover and canopy complexity) were highly predictive of small mammal diversity at the sites. Plots with higher levels of structural diversity and canopy complexity were correlated with more diverse small mammal communities.

NEON structural diversity data used in Sarah Schooler's research

Sarah’s data shows that structural diversity of vegetation is correlated with higher diversity in small mammal populations.

The study suggests that lidar data could be a useful tool for building models of small mammal diversity across large areas. Small mammal diversity is an important indicator of ecosystem health. “This is a proof-of-concept study,” Sarah says. “More work needs to be done to determine whether this model can be applied to other types of ecosystems. But it’s an important first step. Moving forward, hopefully people will expand on it and get concrete data from other ecosystems to build out the predictive model.”

From Plants to Bears, and Everything in Between

Sarah’s interest in data-driven approaches to ecological modeling grew out of her work at the NEON field sites in Wisconsin during the summer of 2017. But her interest in ecology goes back much further than that. Growing up near Madison, Wisconsin, Sarah always had a great appreciation for wildlife and the outdoors. She was thrilled to discover in high school that she could turn these passions into a career in ecology. She went on to earn dual degrees from the University of Washington, with B.S. degrees in Environmental Studies and Environmental Science and Resource Management, and an M.S. degree in Wildlife Biology from Humboldt State University.

Her field experiences have been varied and far ranging. She has studied bears and salmon with the University of Washington Fisheries Research Institute, served as a Fisheries technician for the Washington Department of Fish & Wildlife, conducted visual and radio tracking of cranes for the International Crane Foundation, and worked with the Michigan Department of Natural Resources both in the field and in the lab. Her master’s program took her to Kenya to study the ecology of avian insectivores and insect pests on coffee farms.

She first learned about the NEON project in 2017, when she ran across a posting for summer field technicians. That summer, before starting her master’s program, she worked as a Botany Technician for the NEON terrestrial field sites in Wisconsin. This job took her into the woods, fields and wetlands to conduct surveys of plant diversity, assess course woody debris and leaf litter, and collect root samples for analysis.

Sarah says, “This was a great job for me. Working with the NEON project gave me some really important experiences. They treat their employees really well, and you have the opportunity to develop a wide diversity of skills. I would recommend the experience to any recent ecology graduate.”

She also gained exposure in data-driven research methods and became aware of the huge trove of data that is publicly available on the NEON Data Portal. Without that exposure, she says, her paper on small mammal diversity would never have come to pass.

A Lasting Appreciation for Data-Driven Ecology

Sarah is now enrolled in a Ph.D. program at SUNY–Syracuse, in the School of Environmental Science and Forestry. Her current research focus is on timber harvesting and predator-prey relationships between elk and brown bear in the Kodiak Archipelago.

While her current research does not utilize data from the NEON project, Sarah’s work with NEON has given her a lasting appreciation of the power of data-driven research methods in ecology. “I love collecting data, but I’m even more interested in analyzing data,” she says. “As a field technician, you collect the data but you don’t get to see where it leads.”

She sees tremendous value in the data being collected by the NEON project, especially for graduate students. She says, “I wouldn’t have been able to complete [the small mammal diversity study] without the publicly available data from NEON. I had no external funding, and I would never have been able to collect the lidar data on my own. It’s really amazing to have data of this quality and scope available online.”

As she moves into teaching, Sarah plans to introduce her students to NEON data. “Getting fieldwork experience is important, but remote sensing data enables scientists to scale up projects from surveyed plots to larger areas, allowing students and scientists to ask research questions that are not possible with field data alone. It’s a different way of studying ecological trends.”

Humans not directly responsible for North American reptile deaths

A long-nosed leopard lizard (Gambelia wislizenii) appears in Arches National Monument. ©gilaman
A long-nosed leopard lizard (Gambelia wislizenii) appears in Arches National Monument. ©gilaman

This story was published by Joshua Rapp Learn at The Wildlife Society.
https://wildlife.org/humans-not-directly-responsible-for-north-american-reptile-deaths/

Humans aren’t directly to blame for most North American reptile deaths, according to a large new meta-study that examines a host of research in the United States and Canada.

But they are likely still having an indirect effect on reptile deaths by introducing invasive species and climate change.

“We found that there wasn’t much of an impact of human footprint on reptile mortality. Most of the mortality was from natural causes than human causes,” said Jacob Hill a postdoctoral researcher in wildlife conservation at the State University of New York College of Environmental Science and Forestry and lead author of a new study published in Acta Oecologica.

The study is part of a larger examination using meta-analysis of other research to find the principle causes of death of birds, mammals and amphibians. For this study, Hill and his co-authors focused on reptile mortality.

They looked at 57 studies that tracked reptile populations through GPS devices or other means. The bulk of the reptile populations tracked in the U.S. and Canada were turtles and snakes. The team divided reptile deaths into different categories. Natural death categories included disease, starvation and predation, while human-caused deaths included categories such as directly killing reptiles for harvest, because they were perceived as a threat and vehicle collisions.

They found that 78% of the mortalities occurred due to natural causes while only 22% occurred directly from humans.

Of the direct causes, most reptiles were killed by vehicles. This is likely due to the species’ tendencies to bask on roads and highways, the researchers said. The primary defense turtles use — retreating into their shells — doesn’t work well against cars, Hill said, and snakes — especially venomous ones — don’t typically feel threatened by much at all, and they get hit when they refuse to give up ground to vehicles.

“[Vehicles] can be problematic for reptiles. They have a lot of traits’ that make them very susceptible,” Hill said.

The number of deaths from vehicle collisions didn’t necessarily go up in areas of higher human activity. This suggests that roadkill deaths are more likely due to reptile behavior than an increase in human population, he said.

The causes of reptile deaths differed greatly from the study they did on mammals, which include game species. Those species are often hunted and harvested more than reptile species.

The data in their study didn’t necessarily reflect the whole story of human impact on species, Hill cautions, since humans can indirectly cause reptile deaths by introducing invasive species that prey on them. This could be especially a problem since predation is the highest natural cause of death, according to the study. Climate change or habitat loss can also drive reptiles into marginal environments that can lower their overall survival rate.

Joshua Rapp Learn is a science writer at The Wildlife Society. Contact him at jlearn@wildlife.org with any questions or comments about his article.
Read more of Joshua’s articles.

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