TWS2024: Tegu lures don’t attract bycatch

January 31, 2025 by Joshua Rapp Learn

The best bait attracts the intended species but remains unappealing to others.  

While wildlife managers aren’t confident that scented oils can lure invasive Argentine black and white tegus to stop their spread in Florida, the smells don’t attract the wrong species by accident.

“That’s good—[scented baits] are something that could be used in the future to improve tegu trapping efforts,” said Delana Gonzales, a technician at The Orianne Society, a nonprofit dedicated to the conservation of reptiles and amphibians.

Trail cameras were set up by scent lures intended to attract tegus. Credit: Peter Xiong

Argentine black and white tegu (Salvator merianae) populations took root in the southeastern U.S. after their introduction via the pet trade. They have since established populations in a number of Florida counties as well as parts of Georgia. The reptiles are generalist predators that can take a toll on native species, and Florida added these tegus to its prohibited species list in 2021 to stop people from owning them as pets.

Peter Xiong, a master’s student at the University of Florida, was testing if he could use scented oil to attract tegus. As detailed on a poster presented at the 2024 TWS Annual Conference in Baltimore, Maryland, Gonzales, who was part of the Doris Duke Conservation Scholars Program Collaborative, piggybacked on this research to determine whether the bait also attracted other species.

Delana Gonzales holds a juvenile tegu. Credit: Peter Xiong

In the summer of 2024, Gonzales and her colleagues placed pairs of trail cameras at 24 different sites in the canal systems of southern Florida, just east of Everglades National Park. At each of these sites, they would leave trail cameras on without placing bait for a week as a control study. Then the next week, they put out bait with the cameras. The team used two types of commercially available baits—a mouse oil and a blueberry-scented oil. Neither targets tegus specifically—there are none commercially available that target the reptiles—so the team chose these two oils as the reptiles are omnivorous. They sprayed the scents on clearings on the ground that had cameras on each side. After two weeks, the team repeated the rotation several more times, moving the bait sites each time.

The team repeated these efforts for a total of 2,786 trap nights. Then, they analyzed the photos with the help of a program that searches through photos and identifies species using artificial intelligence.

Species like Virginia opossums also showed up at trail camera stations. Credit: Peter Xiong

What species did scent lures attract?

The program revealed that Virginia opossums (Didelphis virginiana) most commonly approached the sites—researchers detected them 70 times. Coyotes were the second most common (Canis latrans) at 43. Researchers detected 101 rats, but they didn’t narrow down what species these were—several native and nonnative rat species are in the area.

The team also found that while the cameras commonly captured these species in images, they weren’t more likely to show up when there were bait scents than they did in the control weeks without scents. “These oils we were using were actually marketed for these fur-bearing species,” Gonzales said. “We thought it was interesting that they didn’t attract them more, even though that was their target.”

Unfortunately, the baits didn’t attract the tegus either, for the most part. The blueberry oil scent didn’t seem to draw the tegus at all, and the mouse scent only had a small effect that wasn’t that strong.

Iguanas (Iguana iguana) were also captured on trail camera. Credit: Peter Xiong

In the future, Gonzales said that researchers on the team want to explore other types of scents to use for lures. They also want to experiment with different sounds and colors as potential lures in case tegus eventually learn to avoid the scented oils and traps. “Tegus are very smart creatures,” Gonzales said. It would also be useful to expand their test to areas without Burmese pythons (Python bivittatus), another invasive species, she said. The pythons could potentially shift the makeup of medium-sized mammals.

In the meantime, the researchers are still testing scents to see whether they can help wildlife managers trap and remove invasive tegus from Florida. “This will help contribute to better-controlled invasive tegu populations,” she said. “We can reduce the threat to native species.”

Delana Gonzales stands by her researcher poster featured at the 2024 TWS Annual Conference in Baltimore, Maryland. Credit: Joshua Rapp Learn

A global look at effects of climate change on frogs and toads

January 31, 2025 by The Wildlife Society

An international survey of frogs and toads has revealed that global warming and drought are more likely to affect the animals in the Amazon and Atlantic Rainforests. The research published in Nature Climate Change is the most comprehensive study predicting these effects across the planet. “The Amazon and the Atlantic Rainforest are the biomes with the most anuran species and the highest probability of an increase in both the frequency and intensity or duration of drought events,” said Rafael Bovo, an author on the article and a researcher at the University of California, Riverside. “This will be harmful to the physiology and behavior of countless species. These biomes are among the regions of the planet with the greatest diversity of amphibians. Many species only occur in these places.” The researchers also discovered that between 6.6% and 33.6% of frog and toad habitats will suffer from drought by 2080-2100 based on the level of greenhouse gas emissions. That’s important because frogs and toads are sensitive to water loss.

Read the study in Nature Climate Change.

Climate Connections features Paul Taillie

January 30, 2025 by The Wildlife Society

The Yale Climate Connections radio program shared TWS member Paul Taillie’s expertise on how sea level rise and urban development are increasingly challenging a small rodent in the Florida Keys. Silver rice rats (Oryzomys palustris natator) live in coastal marshes and swamps, where they eat critters like crabs and snails. But sea level rise is flooding some of the rats’ habitat and has caused the species to move to higher elevations. Taillie, who is the Secretary-Treasurer of The Wildlife Society’s Wetlands Working Group, said there is a limit to how far they can go, especially with urban development. “This is this idea of coastal squeeze, where animals are kind of squeezed between urban development and rising sea levels,” Taillie told Yale Climate Connections. Taillie’s research has shown that over the next few decades, the species’ habitat will continue to shrink, and it can go extinct by the end of the century. Yale Climate Connections interviewed Taillie at The Wildlife Society’s 2024 Annual Conference in Baltimore, Maryland.

Listen to the radio segment here and read an accompanying article on the Yale Climate Connections website.

The February issue of The Journal of Wildlife Management is now available

January 29, 2025 by The Wildlife Society

The Journal of Wildlife Management is a benefit of membership in The Wildlife Society. Published eight times annually, it is one of the world’s leading scientific journals covering wildlife science, management and conservation, focusing on aspects of wildlife that can assist management and conservation.

Join today for access to The Journal of Wildlife Management and all the other great benefits of TWS membership.

Coyotes (Canis latrans) sometimes prey on species that have been poisoned by anticoagulant rodenticides, which can kill the canids. In the featured article for this issue of JWM, researchers quantified rodenticide exposure in carcasses of urban and suburban coyotes in Southern California and compared these findings to those in rural coyotes in other areas of the state. Nearly all urban coyotes were exposed to anticoagulant rodenticides, they found, compared to only about 42% of rural coyotes.

Other articles look at the impacts of forest management on endangered Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis), raccoon (Procyon lotor) density estimates from camera traps for raccoon rabies management, invasive predators posing a risk to threatened shorebirds and much more.

Log in to read the February issue today.

Leopard roars reveal their identity

January 29, 2025 by The Wildlife Society

Identifying leopards by their roars can help researchers conserve the species threatened by habitat loss and human-wildlife conflict. The International Union for Conservation of Nature lists leopards (Panthera pardus) as vulnerable, but scientists struggle to gather data on them because they are solitary, nocturnal and occur across large expanses of land. In a study published in Remote Sensing in Ecology and Conservation, researchers paired camera traps with autonomous recording surveys in Nyerere National Park in Tanzania. Then, they trained a model to analyze the pattern of a leopard’s roar and match it with the individual. The model successfully identified individual leopards from their roars 93% of the time. The researchers say this information will be helpful for population estimates and may even help conservation practitioners manage landscapes and mitigate human-wildlife conflicts. “Discovering that leopards have unique roars is an important but fundamentally quite basic finding that shows how little we know about leopards and large carnivores in general,” said lead author of the study Jonathan Growcott, a PhD student at the University of Exeter. “We hope it will allow leopards to become the focus of more acoustically complex science such as population density studies and open the door to more work on how large carnivores use vocalizations as a tool.”

Read the study in Remote Sensing in Ecology and Conservation.

Threatened Kansas species recovering

January 28, 2025 by The Wildlife Society

State officials in Kansas have announced that the numbers of three threatened wildlife species are increasing after conducting reviews. The state of Kansas lists the northern map turtle (Graptemys geographica), shoal chub (Macrhybopsis hyostoma) and broad-headed skink (Plestiodon laticeps) as threatened. But in a recent five-year review, the Kansas Department of Wildlife and Parks (KDWP) found that populations of these animals had gone up. As a result, the agency is recommending delisting the fish and two reptile species. KDWP is now seeking public comment on the proposal.

Read more at KSN.com.

JWM: Trail cameras can lure predators to nests

January 27, 2025 by Joshua Rapp Learn

Nest cameras that researchers set up to survey predation on birds under natural conditions might skew their results by inadvertently luring ravens to those birds’ eggs.

These findings could have implications for the usefulness of tools like trail cameras in surveying natural ecology in some environments.

John-André Henden, who was with the University of Tromsø in Norway at the time, had been surveying willow ptarmigan (Lagopus lagopus) in Norway since 2009. These and some other ground-nesting bird species have declined in Arctic Norway, so researchers want to identify their main predators.

Nest cameras have been touted as a possible method to learn about nest predators. But the lack of vegetation in the area, which is mostly barren tundra, to disguise these cameras made Henden and his colleagues wonder whether they would work well. Without much vegetation, common ravens (Corvus corax) and hooded crows (Corvus cornix)—both found in the area—might easily be able to cue in on the work the researchers were doing to find their prey.

Ravens are smart, said Henden, who is now a senior researcher with the Institute of Marine Research, a Norwegian government institute for monitoring. “They are more than capable of connecting the dots with respect to our behavior and activities.”

Who is really behind the camera?

In research published recently in the Journal of Wildlife Management, Henden and his colleagues conducted an experiment to determine whether nest cameras change natural predation levels.

In 2018 and 2019, they set out 50 artificial nests on the Varanger Peninsula in northeastern Norway with quail eggs, which look a lot like the eggs of shorebirds and ptarmigan that breed in the area. Each year, a nearby nest camera took images of 30 of these nests, while 20 nests didn’t have a camera.

They found common ravens were the main nest predators, preying on 96% of the nests. Hooded crows were responsible for 6% of the predations, while Arctic skuas (Stercorarius parasiticus) preyed on 4%. Researchers detected red foxes (Vulpes vulpes) on several camera images, but they arrived at the nests after another predator had already eaten the eggs.

The team discovered a significant difference in predation rates on the nests with cameras versus those without them. In fact, almost 100% of the nests with cameras were preyed on.

While the researchers aren’t sure why this is the case, the lack of much vegetation in this Arctic tundra likely plays a role, Henden said.

A common raven eats a quail egg in an artificial nest. Credit: COAT

Ravens are observant and can detect minor changes in their environment, such as the placement of a nest camera. If they investigate these and discover nests, they could begin to associate the presence of cameras with a meal.

The researchers’ experiment seemed to support this theory. When the team placed nests without cameras in areas with higher vegetation—around 50 centimeters tall—the predation risk was 10%, while the predation risk was more than 70% when vegetation height was less than 10 centimeters.  So even a little vegetation hides the details enough that the ravens can’t find nests as easily.

Do ravens watch researchers to find meals?

The mere presence of humans in some areas may be enough of a clue for the ravens to find nests. While the nests with cameras were preyed on much more than those without them, some 60% of nests without cameras were still preyed on. Ravens and crows might watch humans placing these nests from kilometers away and then come later to investigate once the scientists are gone, Henden said.  

The study highlights how important these corvids are as predators in this area, which is relatively close to the boreal forest.

But it also suggests the limitation of tools like trail cameras in some situations. Henden said their results reveal that it’s important to assess the implications of using technology new to some areas before conducting ecological studies.

In the future, he hopes that using smaller cameras might alleviate the bias that their presence could introduce into environments like the Arctic tundra.

This article features research that was published in a TWS peer-reviewed journal. Individual online access to all TWS journal articles is a benefit of membership.  Join TWS now to read the latest in wildlife research.  

Colorado releases additional 15 wolves

January 27, 2025 by The Wildlife Society

Wildlife managers have released 15 additional gray wolves in Colorado as part of the state management plan. Managers took the wolves (Canis lupus) from the wild in British Columbia and released them in Eagle and Pitkin Counties in Northwest Colorado. The releases were a part of Colorado Parks and Wildlife’s Colorado Gray Wolf Restoration and Management Plan, a multi-year effort to create a robust, self-sustaining gray wolf population in Colorado. CPW has been working on gray wolf reintroduction since voters approved a ballot initiative in 2020. CPW also confirmed the release of five wolves from the original Copper Creek Pack into Eagle and Pitkin Counties, which were recaptured in September.

Read more at CBS News. 

Q&A: A new metric to improve 5-year species status reviews

January 24, 2025 by Joshua Rapp Learn

Five-year reviews—one of the main tools that the U.S. Fish and Wildlife Service (USFWS) uses to track the conservation status of imperiled species listed under the U.S. Endangered Species Act (ESA)—indicate whether a species has recovered, diminished or remained the same.

“A five-year review utilizes the best available scientific and commercial data on a species to determine whether its status has changed since the time of its listing or its last status review,” the Service states.

The results of these reviews affect the future of species—they can ultimately determine whether to downlist a species from endangered to threatened, elevate a species’ status to endangered or remove species from the ESA entirely. They can also determine whether a species or population has been extirpated or gone extinct. Through this process, biologists provide analyses and recommendations about how the status of species could change.

Courtesy of Olivia Davis

However, five-year reviews aren’t perfect. The five-year time period may not be long enough to catch quick changes in species numbers, for example. And they may not very well capture the nuances of how a species might be increasing in numbers in one area while disappearing in another.

As a result, Olivia Davis, a postdoctoral fellow in biology education at Arizona State University (ASU), and her co-authors worked with USFWS biologists and nonprofits to see if there were ways that these five-year reviews might be improved without adding too much extra work for the reviewers. In our latest Q&A, we spoke with Davis about the results of her paper on this topic, which was part of her PhD thesis at ASU, published in Conservation Science and Practice.

Why did you want to look at five-year reviews during your PhD?

While working with a small nonprofit collaborator called the Environmental Policy Innovation Center (EPIC), there had been a lot of talk about monitoring endangered species recovery progress and how that could be done better. One of our collaborators thought that having a metric—or some kind of way to evaluate recovery progress of species alongside the federal processes that they already had in place—could be helpful.

We worked with other nonprofits like the Defenders of Wildlife and the Illinois Natural History Survey, as well as the U.S. Fish and Wildlife Service, directly. Our collaborator with EPIC had developed the plan for this metric. Basically, it was like a scorecard on an Excel spreadsheet. We went through each species and marked whether they were declining or improving in certain areas. The goal was to get a snapshot of the recovery process to see how species were doing and where we could focus recovery efforts once five-year reviews were published.

What metric did you and your colleagues come up with?

It was based on another paper Ya-Wei Li, who was on my committee, and his colleagues had worked on. Basically, they wanted to look at the 3Rs, which is a concept in biology by Shafer and Stein. The 3Rs—resiliency, redundancy and representation—are a way to look at how a species was doing biologically.

Resiliency, which is the first “R,” relates to how a species can withstand stochastic fluctuations or random changes like ebbs and flows. Redundancy relates to whether a species can withstand a catastrophic event, whether that’s related to climate change, a hurricane or something else. Representation looks at how it’s able to adapt to changing environmental conditions. The U.S. Fish and Wildlife Service decided that they liked this as a framework to encapsulate the ability of a species to adapt to external stressors and changes.

We wanted to see the current and projected status of the species. With that knowledge, the USFWS could decide management objectives to implement. Then, we examined if there were already conservation measures being implemented and at what scale. We also looked at the threats facing the species. How were the threats facing the species? Were they getting worse? Were they getting better?

How is this different from the way that USFWS already does their reviews?

Currently, five-year reviews determine whether the species’ status changed since it was listed—it just gives us an overall outcome. When we were designing this metric, we decided that something more helpful for practitioners might be targeted at what exactly was getting better or worse for a species, so we could know where to focus conservation efforts.  

Most of the time, if a species has a five-year review and the status hasn’t changed, but maybe the conservation efforts are being implemented but not on a wide enough scale, then the practitioners could go in and upscale the interventions.

Or, for example, if they noticed that threats are getting worse—in particular, human development—the conservationists could target development as a priority in their management plans. The main focus was instead of just getting this overall “this species is still endangered” outcome, it would allow U.S. Fish and Wildlife Service practitioners more agency and information to know how to act going forward to make things better for the species and what areas to do that in with information they were already collecting.

Do you think this will improve the way that wildlife species are conserved?

We really struggle in conservation, especially on the governmental side of things in terms of resource availability. It’s just such a limited bandwidth and limited resources to get things done. We need to be as efficient as possible in using the time and resources of our practitioners, which often isn’t as much as we would like to have.

This process will benefit practitioners by pulling out specific information that they will be able to act on more directly. They will know where they may need to increase conservation efforts and where they might be able to afford pulling back a little.

A metric like this does pull out more nuanced information about species recovery. That was the big takeaway. Some of this can work, and it can be done efficiently without much extra effort. And we’ll get a bigger snapshot of how a species is doing instead of just “It’s still the same; it’s still not doing well.” Now we know how they’re not doing well and what we can do about it.

Los Angeles wildfires take toll on local wildlife

January 24, 2025 by The Wildlife Society

As flames continue to rage over households and human infrastructure, the fires have also burned wildlife out of house and home. Slow-moving animals who can’t outrun the flames, nocturnal creatures forced to flee during the daylight hours, and animals with young are especially vulnerable. Urban wildlife may face the brunt of this fire—including species like bats that live in the walls or roofs of buildings. Some residents are leaving out water for transient wildlife. Meanwhile, the flames of the Pacific Palisades and Eaton fires have turned back the clock on years of the region’s restoration and conservation efforts. But one wildlife professional has already turned to the future. “Part of bringing back L.A. is making sure that we’re also considering wildlife, nature and habitat,” Miguel Ordeñana, a wildlife biologist and environmental educator at the Natural History Museum of Los Angeles County, told High Country News. “Because if that doesn’t come back, and that’s not being supported, then LA is not going to be what it was.”

Read more at High Country News via Mother Jones.