Ecologists have long known that standing dead trees—or snags—are important for forest dwellers. Snag-reliant woodpeckers, for instance, act as ecosystem engineers, regulating insect pests and create nesting cavities used by other species.
“Snags support multiple functions within forest ecosystems,” said Jim Rivers, of the Oregon State University College of Forestry.
They are so important that in some managed forests, snag creation is part of the conservation tool kit. Crews convert live trees into snags through techniques ranging from sawing off their tops to wounding their trunks to injecting them with disease-causing fungi.
But how well do those techniques work over the long term? And which are the most cost-effective.
In a study published in Forest Ecology and Management, Rivers looked at nearly 800 large Douglas firs that had been converted into snags in southwestern Oregon. He found chainsaw topping was the best way to create snags quickly and keep them in place longer.
Anticoagulant rodenticides are pervasive in the carcasses of dead wolves analyzed by researchers in central and northern Italy.
The ubiquitous presence of these chemicals widely used for rodent control is unique among large carnivores in Europe, say the researchers of a recent study published in Science of the Total Environment.
“This is an emerging threat to large carnivores in anthropogenic landscapes,” said Jacopo Cerri, a postdoctoral researcher in veterinary medicine at the University of Sassari and a coauthor of the study.
Gray wolves (Canis lupus) have been recolonizing many parts of Europe in recent decades, since human persecution has gradually decreased. But as these canids move closer to cities in Europe, some populations are facing novel threats that biologists don’t quite understand.
Cerri’s colleague Carmela Musto, a veterinarian at the University of Bologna and first author of the study and colleagues from the Istituto Zooprofilattico Sperimentale della Lombardia e Dell’Emilia Romagna (IZSLER)—a governmental zoological institution—had been conducting necropsies on wolves found dead in different regions of Italy, including northern Tuscany, Lombardi and Emilia-Romagna, from 2018 to 2022. They found a high number of anticoagulant rodenticides in these carcasses, and they decided to run a more in-depth analysis on trends associated with these chemicals.
Out of the 186 dead wolves the team tested for these chemicals, they found 115, or 61.8%, tested positive for at least one anticoagulant rodenticide.
Rodent diet for city wolves?
The amount of exposure to these chemicals, they found, was higher in wolves found dead closer to cities or other areas of higher human use compared to those with less human use.
“Probably, this indicates that there are systematic differences between wolf diets in different areas,” Cerri said.
This discovery is important as it goes against the common assumption that wolves typically prey on ungulates like wild boar (Sus scrofa) or deer.
The quantity of rodenticides in these wolves isn’t as high as in species like common buzzards (Buteo buteo), which tested positive in 78.3% of cases, or red foxes (Vulpes vulpes), which tested positive in 89.6% of cases. These species rely predominantly on a rodent diet. But the fact that so many wolves near cities have higher levels of rodenticides may mean they are preying on or scavenging species like rats or invasive nutria (Myocastor coypus).
Researchers necropsied wolves in search of rodenticides. Credit: Carmela Musto
These results suggest that the use of rodenticides to home in on the target vermin species isn’t as selective as some may believe, since non-target species are consuming these chemicals.
Some 79 of these wolves tested positive for two or more rodenticides—some had as many as four or five kinds of the chemicals. Cerri said this is likely a reflection of the fact that some people mix different compounds thinking that doing so will better kill rats and other vermin.
Cause for concern
It’s difficult to tell if rodenticides killed any of these wolves directly. But even if the chemicals probably aren’t leading to acute poisoning, it’s likely that they affect the wolves in other ways that may lower their survival in the wild, Cerri said.
Cerri pointed to the example of bobcats (Lynx rufus) in North America—some research has shown that rodenticides likely compromise their immune systems, for example. “I think contamination from toxic chemicals might be more widespread than we think,” Cerri said.
While this study was conducted in Italy, Cerri said that wolves that live near large cities in other countries like France and Germany may also be ingesting anticoagulant rodenticides.
The discovery is important as it highlights a potential limiting factor on wolf populations. Cerri said that wildlife managers will need to consider the effects of potential poisoning when deciding in the future whether to take conservation measures like an endangered listing, for example.
“[Wolves] might have some silent threats that we need to account for,” Cerri said.
Chronic wasting disease has been detected in two deer in British Columbia, marking the first time the deadly disease has been observed in the province.
The two cases were in the Kootenay region, south of Cranbrook, according to the BC Wildlife Federation. In the first case, a sample taken from a hunter-harvested male mule deer (Odocoileus hemionus) tested positive after being sent to the B.C. CWD Program. That deer appeared to be in good condition. The second case involved a road-killed white-tailed deer (O. virginianus).
CWD is a highly contagious fatal disease that affects the central nervous system of cervids, including deer and elk. It has spread through the United States and Canada. Officials have confirmed the disease in both free-ranging and captive cervid populations in 32 states and five provinces.
Mentorship has provided such an important influence in my education and early career, especially now, as I get the chance to serve as a mentor for students and colleagues.
I am lucky that I have supportive mentors in the wildlife management field who both championed and challenged me. I think a good mentor not only offers valuable advice, but also models the qualities and values they believe are important through their own actions.
Amy Carrozzino-Lyon prepares to release a banded female wood duck (Aix sponsa) at Collins Marsh Wildlife Area in Manitowoc County, Wisconsin in August 2017. Credit: Erin Giese
One of my favorite takeaways through observing my mentors is to never stop learning. Learn about a new species, a new habitat or new ecological community, new technology or methods, new ways of thinking, and new geographies and cultures. Continue to challenge what you know and build on it.
Research provides an endless source of questions, many of which are critical to understanding our environment, economy and communities. Yet the fundamental aspect of engaging in research is that we don’t know all the answers, which can be incredibly inspiring and frustrating at the same time. One of the most important lessons I continue to learn in my professional and personal life is to embrace the uncertainty along with taking advantage of the opportunities.
Headshot of Amy Carrozzino-Lyon while visiting Grand Canyon National Park, Arizona. Credit: Scott Lyon
Wildlife Vocalizations is a collection of short personal perspectives from people in the field of wildlife sciences. Learn more aboutWildlife Vocalizations, and read other contributions.
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Yellowstone National Park restricts human access to some areas to protect critical grizzly habitat. In a study in the February issue of the Journal of Wildlife Management, researchers examined how much bears were using these areas and if the restrictions reduced the potential for human-bear conflicts.
Other articles look at pronghorn management in the desert Southwest, duck harvest distributions in the Central and Mississippi flyways, weather and wild turkeys, and more.
Automated laser beams designed to be a nonlethal way to stop birds from damaging crops might be improved to reduce the chance of retinal damage.
“Lasers are being promoted as one of the safer deterrents,” said TWS member Morgan Chaney, a PhD candidate at Purdue University, at a presentation at The Wildlife Society’s 2023 Annual Conference in Louisville. But it’s unclear how much birds’ eyes are expose to the lasers. Chaney is currently developing a model to better predict this, in order to determine ways to improve the safety of the devices.
Bird damage on crops exceeds $4.7 billion annually, Chaney said. Much of this damage comes from nonnative species like European starlings (Sturnus vulgaris) that can reduce corn cobs to empty husks and damage the plants they grow from.
To prevent crop damage, farmers have resorted to all kinds of methods in the past—from shiny reflecting tape, to sound canons and dangerous metal spikes. These lasers were developed as a relatively less harmful approach to unwanted bird foraging.
The principle of the method is that shining lasers—similar to handheld laser pointers—at the birds will scare them into flight. Some of these devices are automated, shooting out shining lasers from a fixed device.
But these lasers may not be harmless—all lasers can cause damage to human eyes, burning retinas and causing permanent vision damage. The effect on bird eyes is less certain, but only highly powered lasers have been shown to cause damage on the eyes of wild birds. “We know that it causes damage in both humans and birds,” Chaney said. Birds may be even more sensitive to laser damage than humans—their eyes have four photoreceptors rather than the three that people have, but there hasn’t been much testing on wild birds to determine any possible effects.
Laser devices have been used as nonlethal deterrent to prevent crop damage from birds like European starlings. Credit: Morgan Chaney
Chaney and her colleagues are studying how bird retinas respond to lasers by exposing European starlings to them under heavily controlled conditions. Controlling the time of exposure and the power of the laser, they examine the birds’ eyes under microscopes to search for signs of damage, such as corneal edema, cataracts and retinal atrophy.
In a second project, the team developed a model that could predict how much exposure birds’ eyes might get from lasers when the devices are at different distances or in different positions.
To do this, the team created an artificial bird using a drone fitted with cameras. They glued a platform with two GoPro cameras pointed either way like a set of bird eyes on top of a quadcopter drone. They flew the device at a station between two laser pointers to see how long the laser might strike the lens in a series of tests. They then developed a model to predict laser exposure times in three different scenarios: when birds flew in the same direction the laser was traveling; when birds flew against the laser; and when the bird was stationary when the laser hit them.
Researchers placed two GoPro cameras on top of a drone to mimic a bird’s eyes. Credit: Morgan Chaney
The researchers need information from the first project to be able to quantify the likelihood of eye damage depending on different positions and distances from the laser. Once they have those data, they can plug them into the model to predict the exposure time of wild birds in the field. All of this work will help them predict the likelihood of lasers hitting birds’ eyes and for how long, as well as the extent of damage that might occur.
“Ultimately, we intend to determine what exposure times would be for a bird in the wild, so that we could use that information to make predictions about the potential dangers for avian eye safety more realistic,” Chaney said.
Their findings are still preliminary, but so far Chaney said the model predicts that birds in the wild may experience eye damage at close distances and low laser speeds. “The probabilities of experiencing damage would go down beyond 30 meters away from the laser,” she said.
The researchers hope to be able to inform safer ways of using these products.
TWS recently welcomed its spring 2024 Joe Burns Memorial Policy intern, Hannah Henry.
Hannah Henry was born and raised in Orlando, Florida and spent her early career studying diverse ecosystems at the University of Florida (UF). While at UF, Henry worked on research and conservation projects for several species, such as green sea turtles (Chelonia mydas), common bottlenose dolphins (Tursiops truncatus) and the St. Vincent Amazon parrot (Amazona guildingii). Henry spent her senior summer with the Florida International University Tropical Conservation Institute in the Caribbean archipelago of St. Vincent and the Grenadines researching endangered species conservation. She graduated Summa Cum Laude from UF in 2022 with a bachelor’s degree in wildlife ecology and conservation.
Throughout her career, Henry has worked at multiple conservation organizations, including the Sea Turtle Conservancy, the Florida Fish and Wildlife Conservation Commission, the National Oceanic and Atmospheric Administration and Texas A&M Harte Research Institute for Gulf of Mexico Studies. She is currently a master’s student in Natural Resources at the Auburn University College of Forestry, Wildlife and Environment where she researches wildlife policy like the Marine Mammal Protection Act and the Endangered Species Act in industries around coastal Alabama. She is passionate about creating successful conservation solutions that suit many stakeholders’ needs.
Hannah Henry holds a northern red snapper (Lutjanus campechanus) during her master’s fieldwork in Mobile Bay, Alabama, where she researches the Marine Mammal Protection Act and Endangered Species Act.
Henry aspires to make a tangible impact on policy and management decisions, enhancing conservation efforts and the well-being of those directly engaged with natural resources. She hopes to develop these interests further with The Wildlife Society. Outside of work, Henry is an avid outdoorswoman who enjoys hunting, fishing, scuba diving and skiing.
During her internship, Hannah will track policies that impact wildlife and wildlife professionals, and engage in coalition meetings, legislative hearings and agency briefings. Through this internship she will have the opportunity to enhance TWS policy resources and assist in writing policy briefs to engage TWS members, as well as write articles about wildlife policy developments for www.wildlife.org.
Stay tuned as Hannah Henry embarks on this exciting journey, contributing to positive impacts in the field of wildlife policy!
The Joe Burns Memorial Wildlife Policy Internship helps advance TWS policy priorities and provides professional experience to students and recent graduates looking to expand their network and expertise. The program is named in honor of one of TWS’ first policy interns, Joe Burns. Burns devoted his career to federal service and spent over 20 years working on behalf of conservation programming within the U.S. Forest Service. Visit wildlife.org/policy to learn more about the program and current offerings.
Why do insects seem to be attracted to light? It’s a peculiar behavior that often doesn’t end well for a moth attracted to a flame or a mosquito attracted to a bug zapper. But researchers believe they may have unraveled they mystery. It’s not that insects are attracted to the light. Instead, they seem to end up in a loop trying to turn their backs to it.
“Contrary to the expectation of attraction, insects do not steer directly toward the light,” researcher wrote in Nature.
Using advanced camera technology, researchers writing in Nature captured images of insects contorting their bodies to face away from the light—a behavior known as dorsal light response. Near artificial light, researchers found, “this highly conserved dorsal-light-response can produce continuous steering around the light and trap an insect.”
As wind and solar energy facilities increase on the landscape, it may be good news for climate change, but it can be bad news for birds that are killed after colliding with turbines and solar panels. By studying the feathers from these birds, researchers were able to identify where the birds came from—knowledge they hope can help reduce these casualties.
“Renewable energy is really great for helping us mitigate climate change,” said Hannah Vander Zanden, an assistant professor in the department of biology at the University of Florida. “But there is an unfortunate part that has consequences for wildlife. We know hundreds of thousands of birds are dying annually at these facilities across North America.”
Vander Zanden is the lead author of a study published in Conservation Biology tapping into repositories of bird carcasses that were found around wind and solar energy facilities. She and her colleagues removed feathers and conducted stable isotope analysis on them to determine the birds’ origins.
“Characterizing the geographic footprint of how far away these effects on wildlife ultimately helps us be able to better mitigate these fatalities,” she said.
Canine handler, Justin Broderick, and wildlife detection dog, Winnie, look for bird carcasses in Southern California. Credit: Todd Katzner
Bird feathers have inert tissue formed where they molt, usually after breeding. Their feathers include hydrogen that is derived through their food and drinking water, which is influenced by the precipitation that occurs in the area. That leaves a specific signature in the feathers that allows researchers to figure out where they originated. Similar processes take place in other species—including humans.
“Most of the work I do is centered around mysteries we can unravel with stable isotopes to understand animal relationships with the environment,” she said.
Luckily for Vander Zanden, many renewable energy facilities were already collecting carcasses of birds that had died there. At one wind energy facility in Northern California, wildlife biologists on staff have been storing bird carcasses in the freezer since 2007. Other facilities conduct monitoring surveys using dogs and humans to find carcasses.
A trough solar system in Southern California. Credit: Tara Conkling
Vander Zanden and her colleagues categorized the birds into local or nonlocal individuals based on the origin determined from their feathers. They found that at wind energy facilities, 51% of the birds that died were nonlocal, and at solar facilities, 73% were nonlocal.
The difference may come down to the characteristics of the sites, Vander Zanden said. For example, glittering solar panels may look like water to migrating birds in the deserts of Southern California—where water is scarce—and attract more birds that are migrating long distances.
The researchers also found that birds originated closer to where they died at wind facilities in Northern California. That may be indicative of nomadic or dispersal movements, Vander Zanden said.
They also found that nonlocal deaths peaked in April, September and October—during spring and fall migrations.
Vander Zanden said this information can be used to inform managers about which species to focus conservation efforts on.
A recent report found that many of Colorado’s native pollinator populations are plummeting, and several bumblebee species are particularly at risk.
Published by the Colorado Department of Natural Resources, the report is the first comprehensive look at pollinators in the state. Researchers found that in the last 35 years, populations of some pollinator species in the state have dropped by more than half. About 20% of Colorado’s 24 native bumblebee species are currently seeking federal protection by the Endangered Species Act due to a significant population declines.
“That’s a huge alarm call, and that’s only for species we have good data for,” said Adrian Carper, an entomologist in the Department of Ecology and Evolutionary Biology at the University of Colorado Boulder and the CU Museum of Natural History.
Researchers found habitat loss, pesticides, climate change and nonnative species—including honeybees—are the main threats to native pollinators.
