Biologists in Alaska have confirmed the first case of a polar bear dying after contracting avian flu.
The state veterinarian’s office announced in December that a polar bear (Ursus maritimus) had died from the H5N1 strain of highly pathogenic avian influenza. Biologists believe the bear, found in the North Slope town of Utqiagvik in October, contracted the virus from scavenging on infected birds.
State veterinarian Bob Gerlach suspects other cases among polar bears have not been detected. “You’re really dependent on the public that’s out there, or the wildlife biologists that are doing surveillance,” he told the Alaska Beacon.
The virus has claimed red foxes (Vulpes vulpes), black bears (U. americanus) and brown bears (U. arctos), in addition to wild birds—particularly waterfowl—and domestic poultry in the state since it was first discovered there in April 2022.
The insecticides that protect crops from pests may be causing obstacles for the long-distance migration of shorebirds.
Researchers have discovered that species like lesser yellowlegs (Tringa flavipes) ingest relatively large quantities of neonicotinoids indirectly through their insect prey or water from wetlands embedded in farmland. The birds don’t directly eat the seeds.
“We’re reporting the highest concentration in a wild bird that isn’t consuming treated seeds directly,” said TWS member Shelby McCahon, a master’s student in natural resources at the University of Idaho.
A growing body of research is uncovering the problems that neonicotinoids are causing bees. While these insecticides are designed to combat crop pests, they can also cause problems, or even death, for other invertebrates.
Less is known about whether these chemicals affect species higher up the food chain. Some work has found that neonicotinoids might lead to declines in northern bobwhites (Colinus virginianus), while other research in Canada has shown that white-crowned sparrows (Zonotrichia leucophrys) lost body mass after ingesting seeds treated with neonicotinoids. These birds also spent longer at stopover sites during migration.
Credit: Shelby McCahon
Neonicotinoids are applied as coatings on the seeds of crop plants and are incorporated into the crops as they grow. But some traces of the chemicals stay in the soil, where rainwater washes them into nearby wetlands. This occurs in the Prairie Pothole region—an important refueling stopover for many shorebirds during migration.
“[Neonicotinoids] are the most widely used class of insecticide, and many shorebirds rely on the Prairie Potholes to fuel their migration,” McCahon said.
Credit: Shelby McCahon
In Alaska, McCahon, pictured above, was studying migratory shorebirds like lesser yellowlegs, whose populations had been declining for more than a half century. A number of factors may be causing a decline in the numbers of migratory shorebirds, but she started to wonder if neonicotinoids might also be playing a role.
The team used wooden carved decoys and speakers that broadcast bird sounds to attract a variety of species to noose carpets—a type of mesh trap pictured above that captures the legs of shorebirds that step on them. They also lured them into areas with large whoosh nets—a type of bungee-powered net that snaps down on birds when they enter a target area. “It goes ‘whoosh’ as it comes over top of them,” McCahon said. In other cases, they used mist nests.
Credit: Kathleen Carey
The team mostly captured lesser yellowlegs, but also caught some greater yellowlegs (T. melanoleuca), semi-palmated sandpipers (Calidris pusilla), pectoral sandpipers (C. melanotos, pictured above), killdeer (Charadrius vociferus) and short-billed dowitchers (Limnodromus griseus).
Credit: Kathleen Carey
The researchers took blood samples of these birds and measured other body metrics like weight, size and body condition. They also sampled the water and the invertebrates in it.
They found that concentrations of neonicotinoids in the water were below toxicity threshold levels to aquatic invertebrates. “Although concentrations were low and not expected to directly impact invertebrates, repeated neonicotinoid exposure in the water could still harm both invertebrates and birds,” McCahon said.
Credit: Shelby McCahon
Across two fall migration seasons, they found that 21% of shorebirds showed evidence of at least one neonicotinoid in their blood. About 3% of the shorebirds had evidence of multiple neonicotinoids. Killdeer, lesser yellowlegs and semipalmated sandpipers had the highest levels during the fall migration. “Compared to the literature, some of these birds have relatively high concentrations,” McCahon said.
Migratory obstacle?
The team hasn’t yet analyzed whether these levels affect the birds’ body condition, foraging or stopover behavior. But McCahon said that other studies have found that neonicotinoids can alter birds’ brains. Neonicotinoids can suppress birds’ appetite, which is critical during these refueling stopovers in the Prairie Potholes. Some of these shorebirds migrate from Alaska all the way down to South America during the fall and back during the spring. They rely heavily on gaining enough fat for this long trip.
Across two spring migration seasons, 60% of the shorebird blood samples had evidence of at least one neonicotinoid, while 17% of them showed multiple neonicotinoid compounds. Since no crops had even been planted at the time spring samples were taken, the high levels in spring blood samples suggest that these insecticides stay in the environment for at least a year after planting, McCahon said.
Credit: Shelby McCahon
The invertebrate analysis is still ongoing. “Neonicotinoids are rapidly metabolized in birds within 24 hours, but repeated exposure could reduce their appetite and cause a rapid reduction in body mass and fat,” McCahon said.
The chemicals also might be reducing the number of invertebrate prey available during refueling.
“Repeated exposure to neonics can cause harm to invertebrates and reduce invertebrate abundance,” McCahon said.
Credit: Shelby McCahon
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.
Humans have caused the extinction of about 1,400 bird species throughout modern human history. That’s twice as many than researchers previously thought. Researchers led a study published in Nature Communications using statistical models to estimate undiscovered bird extinctions since the Late Pleistocene. The findings suggested the largest human-driven vertebrate extinction event in history in the 14th century, the scientists said. During that extinction, the researchers estimated 570 bird species were lost when people arrived in the Eastern Pacific. Another major extinction, they found, occurred in the ninth century BC with people’s arrival into the Western Pacific. “Our study demonstrates there has been a far higher human impact on avian diversity than previously recognized.,” said lead author Rob Cooke, an ecological modeler at the UK Centre for Ecology and Hydrology. “Humans have rapidly devastated bird populations via habitat loss, overexploitation and the introduction of rats, pigs and dogs that raided nests of birds and competed with them for food. We show that many species became extinct before written records and left no trace, lost from history.”
Most wildlife treated in rehabilitation centers were brought there as a result of human disturbance.
By examining wildlife rehab records, wildlife managers can discover previously unknown causes for the decrease of animal populations in a given area or in certain times of the year.
“At least 40% of wildlife injuries can be attributed to human disturbance,” said Tara Miller, a policy research specialist at the University of Virginia’s Repair Lab. “That’s 40% we can do something about.”
Miller, who uses the pronouns they and them, became interested in this topic when they learned about rehabilitators treating black vultures (Coragyps atratus) in the Adirondacks, even though the species had previously only been seen farther south.
That wasn’t the only trend wildlife rehab centers were showing. Animals were coming in sick from lead poisoning and pesticides. Baby animals were arriving earlier in the season. West Nile virus was plaguing animals. “An interesting way to track these changes is to use treatment records from professionals already working with wildlife,” Miller said.
Miller led a study, published in Biological Conservation, in which they and their colleagues collected data from wildlife rehab centers around the U.S. and analyzed it to discover trends. Although rehab centers mostly treat animals that people interact with and care more about, Miller said these findings can still inform wildlife management and conservation.
Collecting the data required a lot of patience—and digitizing. Miller visited some centers in person, made copies of paper records, and typed up data into spreadsheets. They also were able to tap into some gigantic newly available digital datasets. For example, the Wildlife Center of Virginia created the WILD-ONe database that includes information from wildlife centers across the United States. “Tara was there during a golden moment when centers were moving away from paper records to digitization,” said Richard Primack, Miller’s advisor.
After collecting and analyzing more than 600,000 wildlife treatment records from almost every U.S. state and eight Canadian provinces covering the last 10 years, the team found that vehicle collisions were the biggest reason for wildlife coming to the centers. Human activity, in general, accounted for 40% of the dataset, including things like building collisions and fishing-related incidents. That number could be even higher, since some records noted an injury but the cause was unknown.
The study findings also suggested species like bald eagles (Haliaeetus leucocephalus) had high levels of toxins such as lead from ammunition, although some centers reported that they lacked funding to test samples.
Season also mattered; higher lead poisoning incidents correlated with the late fall and winter hunting season.
In addition, hurricanes and flooding led to more species coming to rehab centers. “These big weather events are increasing in frequency and intensity because of climate change, and can be very harmful to wildlife,” Miller said.
The team also found that about one third of the animals that enter rehab centers are released back into the wild, with different rehabilitation success rates for different species.
Miller said this study just scratched the surface regarding what types of insights the data can provide. Scientists can focus on an endangered species, for example, or pull out the trends in a specific state or county. While the wildlife center information is not the scientist’s ideal randomized study, it can give researchers a good place to start.
Miller also pointed out that information on where injuries or illnesses are happening can inform wildlife management, such as where to build wildlife crossings on roads or whether to change speed limits.
When wolves prey on beavers in and around Voyageurs National Park, cascading effects ripple throughout the whole ecosystem.
Researchers have been documenting wolves going after the aquatic rodents, but they didn’t know much about some of the dynamics—factors that could have implications for the environment, since beavers are ecosystem engineers.
“We’ve been really trying to understand beaver interactions on a more broad scale,” said Thomas Gable, project lead of the Voyageurs Wolf Project. “And then, how do those interactions influence larger ecological processes?”
Beavers that travel farther from the water are more at risk from wolf predation. Credit: Thomas Gable
Gable led a study published in Proceedings of the Royal Society B, in which he and his colleagues took data on gray wolf (Canis lupus) predation on beavers (Castor canadensis) in the Greater Voyageurs Ecosystem. They wanted to understand where predation was happening and if they could uncover any patterns, including if wolves were preventing beavers from altering forests by cutting down trees.
The researchers used GPS collars to track wolves between 2015 and 2022, zeroing in on the months between April and October to identify predation events when beavers would be active. For the beaver part of the study, Gable and his colleagues used remote cameras to determine where beavers went to find food and how far they traveled.
wolf pup in a beaver lodge den. Researchers were interested in beaver-wolf dynamics. Credit: Thomas Gable
The team found that wolves generally kill beavers when the rodents travel greater distances from their ponds to forage. Gable believes this is an evolutionary pressure that leads to more beavers foraging closer to home to avoid being killed by wolves. “Wolves are disproportionately killing the beavers that forage farther from water. In other words, the beavers that make riskier decisions when foraging,” he said.
This could result in changes to the forest. Beavers using shorter foraging trails to avoid wolf predation are likely to cut down certain tree species that have the most food for them, including aspens, willows, maples and birch, leaving their ponds ringed by evergreens like balsam, spruce and pine, “We suspect the size of the ring of conifers ends up being determined in part due to wolf predation because wolves appear to be preventing beavers from going farther inland,” Gable said.
“Wolves are connected to some of these forest-level processes through their predation behavior,” Gable said. “That’s an important thing when trying to understand how ecosystems work.”
Each spring, lesser long-nosed bats (Leptonycteris yerbabuenae) make the journey from south and central Mexico to breed around Tucson, Arizona. Researchers are using a wildlife tracking system developed in Israel, and never before used in the United States, to better understand their foraging behavior. The Atlas system uses tiny radio transmitters glued to the bats’ backs, allowing researchers to track them through a network of antennas.
Watch the video from the Arizona Game and Fish Department below.
Wolf range in the Great Lakes region is unlikely to be negatively affected by projected human land use and climate change in the U.S. Great Lakes region.
“[The Great Lakes] wolf population is a good example of a conservation success story in the United States,” said TWS member Merijn van den Bosch, who received his PhD at Michigan State University investigating the spatial ecology of gray wolves.
While gray wolf (Canis lupus) populations have been expanding in the Great Lakes over the last four decades, van den Bosch and his colleagues wondered whether this success would last in the future.
For a study published recently in Ecosphere, they examined winter tracking surveys from the Great Lakes states that currently share a wolf population: Michigan, Wisconsin and Minnesota. The team collected data during the winters from 2017 to 2020 from surveys coordinated by the departments of natural resources of these three states.
Changing climate and development
The team then used future climate change prediction scenarios by the end of the 21st century: two in which the world keeps the rise in average global warming at about 3 degrees Celsius by reducing greenhouse gas emissions, and two other less sustainable futures in which the average global temperature increases by up to 5 degrees Celsius.
The researchers also examined socioeconomic projections parallel to the climate change predictions for the Great Lakes states as a way of understanding predicted land use change through 2100. That included a look at how landscape composition may change, leading to increases or decreases in forested areas, areas used for agriculture, or urban areas. All of these changes can affect suitable wolf habitat.
Future projections on land use change may favor wolves in some ways. Credit: Michigan State University/Michigan DNR
Resilient to change
The researchers found that wolf range in the Great Lakes region is likely to be resilient to both factors.
“Overall, it seems that wolf range in the Great Lakes is unlikely to be negatively affected by land use and climate,” van den Bosch said. In fact, under the most sustainable scenario, available wolf habitat may even expand by up to 35%, their models found, primarily due to increases in forest cover and decreases in areas used for agricultural activities.
Wolves aren’t particularly sensitive to climate, which may be one reason wolf habitat in the Great Lakes is expected to increase or at least remain stable—wolves are found in climates much warmer than the Great Lakes region.
“We expected that climate change throughout this century might not have a big impact when you consider where wolves live or have lived,” van den Bosch said, adding that today, they are found everywhere from India to the high Arctic.
Wolves are often resilient to climate change. Credit: Michigan State University/Michigan DNR
Land use change could restrict wolves in some areas due to increased agricultural activities and urban development, which not only provide less suitable habitat for wolves but also can form barriers to wolf movement. But overall, the land use changes predicted in parts of the Great Lakes won’t likely negatively affect wolves. Partly, this may be due to the projection that the amount of land used for agriculture may decline, resulting in increased forest cover.
Even in a less sustainable future where cities in those states increase up to 3%, no large losses of forest cover are expected in this region, and the amount of habitat available to wolves would remain stable. Van den Bosch said this worst-case scenario still isn’t that bad for wolves, as areas outside of cities that would be urbanized are already unsuitable for wolves, and 3% is a small fraction of the landscape.
These projections are parallel to the recent growth of wolves, which have far exceeded recovery targets set by the U.S. Fish and Wildlife Service when the species was listed under the U.S. Endangered Species Act in 1974, van den Bosch said. The current population of these three states is estimated at 4,200 wolves—far above the original recovery goals of 1,200 for Minnesota and 150 total for Wisconsin and Michigan. Great Lakes wolves now form the largest population in the contiguous U.S., he said.
Wildlife officials captured a Mexican wolf (Canis lupus baileyi) that wandered beyond the recovery area. It was the female wolf’s second venture outside the repopulation area. The New Mexico Game and Fish Department captured wolf F2754, nicknamed Asha, on Dec. 9, near the town of Coyote, N.M. She has been paired with another wolf in captivity in the hopes of increasing the population.
“By pairing her with a carefully selected mate in captivity, we are hoping she will breed and have pups this spring,” Brady McGee, a Mexican Wolf Recovery Coordinator for the U.S. Fish and Wildlife Service, told the Arizona Republic. “The best outcome for her is to be released back into the wild, where she and her offspring can contribute to Mexican wolf recovery.”
In the Appalachian Mountains of western Virginia, hunters had noticed that as coyote and bear populations climbed in the region, white-tailed deer numbers were falling. That raised concerns that these carnivores were preying on young fawns, threatening the stability of a struggling population.
Yet when researchers looked into the effects of predators on the deer, they found that coyotes weren’t the biggest threat, and the deer population wasn’t at risk.
“The story that emerged was a little bit different than what was expected,” said Michael Cherry, Stuart W. Stedman Chair for White-tailed Deer Research at the Caesar Kleberg Wildlife Research Institute in Kingsville, Texas.
While white-tailed deer (Odocoileus virginianus) are thriving to the point of becoming a nuisance throughout much of the eastern U.S., in the southern and central Appalachians, deer populations are struggling. In a study published in PLOS ONE in August, researchers found that poor habitats and predation were driving down deer numbers in northern Georgia.
The deer population in Bath County, Virginia is also more vulnerable than some, and it’s one that state wildlife officials have been working to maintain to meet hunter demands.
“This has historically been a really popular place for hunters to go and pursue deer,” said Cherry, lead author of the recent study published in the Journal of Wildlife Management. “It’s a beautiful landscape with an abundance of public land on the George Washington National Forest.”
To find out how much predation was responsible for population declines, researchers used GPS collars and vaginal implant transmitters on 38 pregnant female deer. Once the animals gave birth, the team was able to find and collar 57 newborn fawns. If the collars stopped moving, researchers rushed to investigate how the animal it belonged to died. If they found a kill site, they searched for clues—scat, tracks, feeding behavior, sometimes even analyzing saliva left on the carcass—to determine what predator species was responsible.
The central Appalachians have a growing list of possibilities. Populations of coyotes (Canis latrans), bobcats (Lynx rufus) and black bears (Ursus americanus), are all on the rise. Yet the detective work proved pretty easy, Cherry said.
“Bears consume basically the whole fawn all in one sitting,” he said, and that was mostly what they found. Of the 57 fawns they collared, 37 died. Nine died from causes such as abandonment, malnutrition and disease. The other 28 were killed by predators, with bears responsible for nearly two-thirds of the predations. Bears killed 18 fawns. Bobcats killed five. Coyotes—whose growing numbers first raised concerns—killed just three.
Using that data, researchers were able to model the effects these predators had on the deer population. They found that, despite the predation, deer numbers were stable enough to allow for a modest increase in doe harvest.
The findings were not exactly a surprise, Cherry said. Adult female survival is much more important than fawn survival in driving population levels. And despite hunter concerns, the region is not very conducive to coyote populations.
While hunters were probably right in noticing that the deer were declining as coyotes were increasing, he said, the two probably weren’t related. Reduced forest harvesting that creates early successional habitat and irregular hard mast crops of acorns probably play the biggest roles.
“Overall, we think there has just been a decline in habitat quality for deer in the region,” Cherry said.
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 nowto read the latest in wildlife research.
Efforts to return the American chestnut tree to the landscape have hit a stumbling block. Once a staple of forests throughout the eastern United States, the American chestnut (Castanea dentata) provided nuts for wildlife and humans, as well as wood for building, but at the beginning of the 20th century, a pathogen wiped out nearly all of the trees. For the past decade, researchers have been experimenting with genetic engineering to help the trees to survive the fungus. The method was promising, but this month the American Chestnut Foundation pulled its support from one of the efforts due to mounting concerns. Researchers plan to seek federal funding to continue with the program.
