In the debate over real or artificial Christmas trees, the birds may have an opinion. In many cases, some conservationists say, Christmas tree farms can function like young forests, offering resources for migrating birds and other species.
When the Society for the Protection of New Hampshire Forests started a Christmas tree farm, the New York Times reports, managers found birds, deer and foxes were attracted to the landscape.
While not every conservationist is a fan—concerns range from pesticide use to lack of tree diversity— many see Christmas tree farms as providing important benefits that might not be available without these acres of manicured trees.
“None of that is to say that a Christmas tree farm is a replacement for untouched nature,” David Mizejewski, a naturalist with the National Wildlife Federation, told the Times. “I encourage people to think of things through an ecological lens, where everything has a life cycle. And what’s more important is that while it’s living, it’s actually contributing to that ecosystem.”
The Wildlife Society, through our continued partnership with the USDA Forest Service, is excited to announce the availability of research assistantships for Native undergraduate or graduate students in the summer of 2024 as part of the Native American Research Assistantship (NARA) Program. Applications are being accepted now through Jan. 26, 2024. Visit the link above for additional information and instructions on how to apply.
Established in 2014, NARA provides training for careers in natural resource and conservation-related fields, promotes Native student advancement in the wildlife profession, and elevates Indigenous Traditional Ecological Knowledge (ITEK) within federal research projects.
“As we enter the 10th year of this collaborative initiative, I reflect on the unifying strength of our mission and appreciate the opportunity for TWS to support and empower Native students along their professional journeys,” said TWS CEO Ed Arnett.
“We are proud of the achievements and contributions of past NARA participants and look forward to witnessing their continued growth and success within the wildlife profession and beyond. We are also grateful for the longstanding support of our partners at the U.S. Forest Service in helping to create and provide these unique opportunities to advance the next generation of wildlife leaders.”
Applicants selected for NARA will engage with representatives from TWS, while learning from and working with an interdisciplinary team of USFS Research and Development on a three-month research project. This year, we are seeking Native students for four projects during the summer of 2024. Each assistantship will include a paid stipend of at least $6,500.
For detailed information on the available opportunities in 2024 and instruction on how to apply, please visit the Native American Research Assistantship (NARA) Program. The deadline for applications is Jan. 26, 2024.
Two men have been charged with illegally killing some 3,600 birds, including bald and golden eagles, and selling their parts and feathers on the black market. Prosecutors accuse the men of killing the birds on or near the Flathead Indian Reservation in western Montana and elsewhere. A federal grand jury in Montana indicted the men on charges of violating the Bald and Golden Eagle Protection Act, violating the Lacey Act concerning wildlife trafficking, and conspiracy. The men face up to 11 years in prison and fines of over $200,000 in what one of the defendants reportedly called a “killing spree.”
After shooting the eagles, prosecutors said in court records, “the defendants then illegally sold the eagles on the black market for significant sums of cash across the United States and elsewhere.”
There’s nothing better than having a meal and drink by the poolside—whether you’re a human or a bat.
Researchers have found that these artificial water bodies may be an important foraging and drinking resource for bats as South Africa climate gets dryer due to global warming.
“If bats can locate and access [swimming pools], then they’ve got water all year round if they need it,” said TWS member Tory Bennett, an associate professor in environmental and sustainability sciences at the Texas Christian University.
The Amakhala Game Reserve in the Eastern Cape of South Africa sits on land that Dutch colonists converted for farming. But with ecotourism becoming more popular, the property was transformed to a game reserve.
Bennett wanted to get a better idea of bat population success there, since the taxa is an indicator of ecosystem health. She had previously noted bats using swimming pools to forage and drink in Texas and wondered if they may be using swimming pools at several different hotels on the reserve.
Poolside listening
Bennett and her colleagues surveyed bats using acoustic detectors set up around swimming pools at the tourist lodgings on the reserve. For a study published recently in the Journal of Wildlife Management, Bennett and her graduate student James McGee analyzed data collected from detectors at two pools from July 2018 to December 2020.
They recorded 24,909 bat echolocation calls above the swimming pools and identified seven out of 23 local species: Cape horseshoe bats (Rhinolophus capensis), Geoffroy’s horseshoe bats (R. clivosus), Botswana long-eared bats (Laephotis botswanae), Cape serotine bats (Neoromicia capensis), Natal long-fingered bats (Miniopterus natalensis), Egyptian free-tailed bats (Tadarida aegyptiaca), and lesser woolly bats (Kerivoula lanosa).
Since bats have distinct echolocation calls for different activities, researchers can identify specific resource use, including whether bats were approaching a water source, drinking or foraging. By analyzing the recordings, the team found 1,374 calls related to foraging and 9,286 calls related to drinking.
These results suggest that bats were mostly using the swimming pools for drinking water, while some bats were feeding above these pools, perhaps on insects attracted to the water. But use depended on species. For instance, the Cape serotine and Botswana long-eared bats were using the pools more as a drinking source, while Egyptian free-tailed bats used them for foraging more, and Natal long-fingered bats used the pools more evenly for both. Researchers could tell that these species were approaching the water surface but recorded no distinct feeding or drinking calls, potentially because calls from these species are so high frequency that are difficult to detect and record. They were certainly using pools as a resource though, Bennett said.
While the International Union for Conservation of Nature doesn’t list any of the seven bats as conservation concern, five of the 23 species found locally are designated vulnerable. Pools might provide a buffer for bats—natural water sources in the area are increasingly drying up due to climate change, and this area has been experiencing a long drought. But swimming pools represent a permanent source of water.
“The take home message, so far, is that we should not exclude swimming pools as a potential water resource for bats,” she said, adding that migrating bats could use them as a stopover resource while residents can use them all year. “They may not have another choice at this point.”
In future research, she plans to use cameras to get a better idea of what the species are doing at the pools, particularly among the horseshoe and woolly bats. She and her colleagues also want to compare how bat activity and resource use above swimming pools compares with activity and use above natural water sources in the area. This could reveal why bats are choosing to use these pools in the first place.
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.
Loud noise in poor, urban neighborhoods is not only dangerous to people living there. It can also affect wildlife.
Urban ecologists have been looking at how systemic biases and racism shapes urban ecology and biodiversity. For instance, poorer areas often have higher levels of air and water pollution and less green space. But noise has often been left out of that research.
Assistant professor at Colorado State University Sara Bombaci hoped to close that gap. But finding the data proved difficult. Bombaci and her team hoped to use biodiversity datasets in poorer neighborhoods that had historically been redlined—areas deemed risky investments because of their large minority populations.
“We have this large spatial dataset of noise across the U.S., and we have the redlining maps of noise across the U.S.,” Bombaci said. “We were really hoping to just pair that with some biological data.”
But just like many things in poorer neighborhoods, the datasets showed inequity, too. Other research has also shown that citizen science data like eBird or iNaturalist are biased. “It’s also not equitably distributed across cities,” she said.
That led them to conduct a literature review to understand what past studies have said about urban noise effects on wildlife. For their research, they assumed that noise would be higher in redlined communities and that noisier areas would have greater impacts on wildlife.
“We pulled out the numbers of noise that were affecting wildlife, and we paired that with the numbers of noise levels that are found in our redlined communities,” she said. “We speculate that that those levels of noise could be impacting wildlife to a greater degree because of the cumulative evidence we found throughout the literature that says as noise increases, the impact to wildlife also increased.”
A meadowlark along a road. Urban areas have less green space and other resources for wildlife. Credit: Sara Bombaci
Their findings appear in a study published in Nature Ecology & Evolution. Some of what they encountered was expected, like inequities in noise. “But what was surprising was how clear those patterns were,” Bombaci said.
The team knew that human population size would be a strong predictor of noise. They ran a model to see if population size would swamp out other factors like redlining. But they found that redlining was the stronger predictor of noise pollution compared to population size.
They also looked at the maximum levels of noise that neighborhoods were experiencing. In their research, they looked at 83 cities, with each neighborhood graded, with A being the higher income areas with a higher white population and D grades being the lower income with higher populations of people of color as a result of redlining.
Greenlined neighborhoods that were A-graded nearly always had maximum noise levels below 90 decibels, which is the level that noise can be harmful to people. “That’s the level where human health is drastically impacted,” Bombaci said. Similarly, that’s the level that cumulative impacts to wildlife are greatest.
When they looked at redlined neighborhoods that were D-rated, almost all of them have maximum noise levels above 70 decibels. “That figure matters because it’s the EPA upper limit to avoid hearing degradation,” she said. “The EPA suggest we should manage areas to keep them below 70 decibels to avoid those hearing impacts to humans, you can imagine they also have cascading impacts to wildlife.”
Many of the studies they looked at showed that noise affects wildlife vocalizations as well as population sizes. Bombaci said while this can have negative effects on wildlife itself, lack of wildlife can also negatively affect human health. “There’s several studies that have documented that having access to nature and biodiversity is really important for human health and well-being, or even just access to natural soundscapes,” she said. “What’s good for biodiversity can be good for human wellbeing as well in cities. And so human communities in these redlined neighborhoods, not only are they dealing with the human health impacts of having this elevated level of noise, but also receiving less benefit from nature itself.”
There are some ways to help reduce noise in some underserved communities, though. For example, noise barriers in construction or industrial zones can limit noise. Vegetation or tree lines can also buffer noise. There’s also new smart technology, Bombaci added. In Paris, noise radars are measuring the noise levels of moving vehicles and identifying their license plates to fine vehicles that are making too much noise. There’s also quiet road and pavement technologies. Changing the sirens on ambulances is also an option. These changes can benefit people as well as wildlife.
“This study highlights how you can simultaneously advance scientific understanding and wildlife conservation, and also think about how you can integrate or consider these systems of oppression and how they can shape biological processes,” Bombaci said.
Arctic temperatures reached the warmest they ever were this past summer. A recent NOAA report card showed that as a result of this warming climate, the area is becoming wetter, greener and less icy. This past summer, those warm temperatures in the Arctic also translated to intense wildfires and flooding due to glacial thinning. The recent report, written by 82 authors in 13 countries, shows that looking at a satellite record that covers the past 45 years, the last 17 years have had the smallest annual minimums for sea ice cover. This past summer, the sea ice cover was the sixth smallest on record. The report touched on ways these changes may affect ships, salmon populations, flooding and more.
Hamish Spencer was supposed to be on vacation, but a birding trip in Colombia led to an encounter with an extremely rare bird—a green honeycreeper (Chlorophanes spiza) with green female plumage on one side and blue male plumage on the other.
“Many birdwatchers could go their whole lives and not see a bilateral gynandromorph in any species of bird,” said Spencer, a zoologist at the University of Otago in New Zealand, who published the sighting in the Journal of Field Ornithology. “The phenomenon is extremely rare in birds.”
It’s only the second recorded example of gynandromorphism in the green honeycreeper in more than 100 years.
Spencer credits fellow birder John Murillo for spotting the bird and capturing photos of it. Those images are “arguably the best of a wild bilateral gynandromorphic bird of any species ever,” he said.
Climate change may be turning more Arizona tiger salamanders to cannibalism.
Many salamanders occasionally eat each other. “Cannibalism in salamanders isn’t a unique thing—pretty much all salamanders will cannibalize,” said TWS member Melissa Ocampo, a master’s student in watershed science at Murray State University in Kentucky.
The mouths of cannibal morph larvae are wider. Credit: Melissa Ocampo
Scientists, including Ocampo’s supervisor Howard Whiteman, had conducted research in the 1990s on cannibalism in Arizona tiger salamanders (Ambystoma mavortium nebulosum), a subspecies of western tiger salamanders (A. mavortium), in Colorado, where they are also found. That research revealed that Arizona tiger salamander larvae have two different body forms—a typical body type and a cannibal morph, which includes individuals with “super wide mouths with crazy sets of teeth” that help them eat other tiger salamanders, according to Ocampo. Once they metamorphose into adults, they lose these cannibal morph features.
The smaller mouth of a typical morph larva. Credit: Scott Thomas
Those morphs can be affected by the environment where they live. In the Rocky Mountains of Colorado near Crested Butte, many of the ponds these salamanders live in are seasonal. They appear from meltwater in April and May, before slowly drying up in the summer. The females lay eggs to coincide with this period, but the seasonal nature of the waterbodies puts a deadline on development for the young salamanders. “Larvae in the temporary ponds have to metamorphose before the pond dries,” Ocampo said.
A cannibal morph larva (left) and a typical morph larva (right). Credit: Melissa Ocampo
The Rise of the cannibals
Whiteman’s earlier work had found that as salamander density increases in these ponds, the ratio of cannibal morphs increases. This means that if the ponds dry up more quickly, more cannibals begin to appear. He also found that a higher density of invertebrate prey seemed to result in more cannibal morphs. More invertebrate prey items lead to more varied sizes in salamanders, which is also associated with the cannibal morph.
By contrast, permanent ponds usually don’t host any cannibal morph tiger salamanders.
But since this work in the 1990s, research had slowed down on cannibal tiger salamanders, and nobody had looked at how temperature or increased drying rates influence the cannibal morphology.
Graduate students Karissa Coffield (left) and Melissa Ocampo (right) used nets to survey salamander populations in ponds in Colorado. Credit: Melissa Ocampo
As part of her master’s work, Ocampo resurveyed the ponds and populations her supervisor had examined using the same techniques as the previous research. She and her colleagues ran nets through the ponds to capture larvae to get salamander counts. They also counted the ratio of cannibal morphs versus typical morphs.
They also estimated the invertebrate density by dropping a cylindrical garbage can with the bottom cut out into the pond, similar to what Whiteman did previously. They would then scoop out all the invertebrates and salamander larvae inside.
Credit: Joshua Rapp Learn
Climate cannibals?
On a poster at The Wildlife Society’s 2023 Annual Conference in Louisville, Kentucky, Ocampo described how the surveys have so far confirmed many of Whiteman’s findings in the 1990s. Ocampo’s work is still ongoing, but she predicts that the ratio of cannibals may be higher now than it was 30 years ago, since the ponds are drying up earlier due to climate change. There has also been less snowpack accumulation, which ultimately leads to less water in the ponds during the spring and early summer.
The experimental set up involved a number of bins with different conditions. Credit: Melissa Ocampo
To supplement this work, Ocampo also ran experiments with salamanders. In the summers of 2022 and 2023, she and her colleagues placed salamander larvae in tanks with different treatments. They left one at ambient temperature, while increasing the other by three degrees Celsius. The team also included three different density treatments as a proxy for what would happen when ponds dried up faster or slower—bins with four, eight and 12 salamanders each.
Over a six-week period, she and her colleagues checked the salamanders for morphological changes as well as evidence of cannibalism.
A larva (middle) cannibalizes another larva (right). Credit: Melissa Ocampo
Ocampo didn’t find any difference in the number of cannibal morphs between the various treatments. But they did find cannibals disguised as typical morphs. Salamanders in the bins with higher densities and hotter temperatures cannibalized each other more.
Researchers still don’t understand all the factors that may play a role in cannibalism and in the morphological changes to a cannibal type.
But Ocampo’s work on the topic is ongoing. Arizona tiger salamander populations are decreasing in parts of their range due to the introduction of sport fish in some of their breeding ponds. If introduced fish aren’t around, the Arizona tiger salamander is a keystone species in the Rocky Mountains, acting as top predators in fishless ponds. A better understanding of the causes of cannibalism can help researchers determine the effects of hotter future climates on population and ecosystem health in the Rockies.
Credit: Melissa Ocampo
This photo essay is part of an occasional series from The Wildlife Society featuring photos and video images of wildlife taken with camera traps and other equipment. Check out other entries in the series here. If you’re working on an interesting camera trap research project or one that has a series of good photos you’d like to share, email Josh at jlearn@wildlife.org.
Despite their smaller size, Mexican wolves prey on the same species as their larger gray wolf cousins to the north—and in nearly the same quantity.
Many researchers have looked into gray wolf diet in northern states and in Canada. But nobody had ever published research on the diet of Mexican wolves, despite a number of informal work and field observations.
Currently the Endangered Species Recovery Section Manager with the Washington Department of Fish and Wildlife Julia Smith, and her colleagues used GPS collars and field observation to determine whether the diet of Mexican wolves (Canis lupus baileyi) was different from that of gray wolves (Canis lupus).
Julia Smith uses radio telemetry equipment to track wolves. Credit: Arizona Game and Fish Department
From 2015 to 2017, the researchers followed 10 wolf groups in Arizona during a winter study period from February to March, and a summer study period from June to July. Sometimes, the team collared one wolf in the pack. Other times, they collared more. Whenever the team saw clusters of GPS locations of wolves, they would go out into the field to determine whether a kill had happened, what prey species was killed, and how many members of the pack were involved.
They found that overall, Mexican wolves tended to kill about the same number of prey as other gray wolves.
“Mexican wolf kill rates are pretty similar to wolf kill rates in more northerly ecosystems, which is probably not too surprising because wolves are wolves,” said Smith, who was the Mexican Wolf Project Field Supervisor with the Arizona Game and Fish Department at the time of the research.
Wolves mostly focused on elk (Cervus canadensis)—often taking them down in packs. In a few cases, single wolves took down adult female elk, though these were either older or had splayed hoofs. “It’s cool to see in person how wolves hone into the particular weaknesses of these animals and exploit them,” Smith said.
On the one hand, Smith isn’t surprised that these relatively smaller wolves still manage to take down elk—“they are a highly adaptable critter,” she said of the wolves.
The remains of an elk preyed on by Mexican wolves. Credit: Julia Smith
But, on the other hand, Mexican wolves are only about 50 to 80 pounds on average compared to the 90-100-pound average of gray wolves in the north.
The data showed that like wolves elsewhere, Mexican wolves typically take down more calves, especially in the summer when the ungulates are still small. In this season, wolves killed more animals in general than they did in the winter.
The researchers also found that wolves killed mule deer (Odocoileus hemionus) sometimes—though not as much as previous researchers had assumed. Smith did caution that their results may have missed some mule deer as these smaller prey species could be eaten more quickly, before researchers could detect a kill based on the GPS clusters. It’s also likely that the wolves kill even smaller prey species that were undetected using this technique, like rabbits and wild turkey (Meleagris gallopavo). “But they are in no way dependent on those smaller prey items,” Smith said.
Julia Smith and a colleague measure a Mexican wolf in the field. Credit: Arizona Game and Fish Department
They didn’t find any evidence of Mexican wolves preying on bighorn sheep (Ovis canadensis) or pronghorn (Antilocapra americana) in the area.
Smith said this study gives researchers and wildlife managers a baseline idea of what to expect from Mexican wolves, as they continue to spread through Arizona and New Mexico.
Artificial light sources are luring birds into cities during their migrations. Researchers recently found artificial light is a top indicator of where birds will stop over. In a study published in Nature Communications, researchers used weather data to determine bird density at stopover sites in the U.S. Out of 49 predictors of stopover density, elevation was number one and artificial light was the second highest predictor. That’s a problem, since the source of the light is often buildings that can lead to collisions. In addition, cities have less habitat and food, and more people and cats, which can cause problems for birds. “These stopover locations are the fueling stations,” said Kyle Horton, an assistant professor in Colorado State University’s Department of Fish, Wildlife and Conservation Biology. “If you’re on a cross-country trip and there’s no fueling stations, then you’re stranded. If they don’t have a good spot to rebuild energy supplies, migration can’t happen.” Out of 49, predictors.
