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.
After two winters of an experimental program to feed Florida manatees in the wild, wildlife agencies say they plan to discontinue the effort this winter. “After careful consideration, the agencies are not providing manatees with a supplemental food source at the beginning of the winter season,” the Florida Fish and Wildlife Conservation Commission announced. “However, staff developed a contingency plan for supplemental feeding which they will implement if needed.”
Manatees (Trichechus manatus latirostris) declined from a lack of native seagrass in the Indian River Lagoon, where they congregate in the winter. The situation prompted the U.S. Fish and Wildlife Service to declare the die-off an Unusual Mortality Event. That declaration continues, but biologists determined that “there are currently no indications that manatees in this region are in poor or compromised body condition.”
Federal and state officials plan to continue to work with partners to monitor seagrass and manatee health conditions.
Scientists recently uncovered variations in methylmercury concentrations in U.S. amphibians. While researchers don’t yet know at what concentration the chemical can be harmful, the researchers hope the data can shed light on which species may be at risk from exposure.
Biologists have been interested in how contaminants like mercury affect amphibians, because they live in aquatic environments where they are more exposed to some contaminants compared to terrestrial species. Formed when mercury is converted by microbes in water, methylmercury can be extremely toxic, adding another potential risk to species already threatened by habitat loss and disease.
In a study published in Environmental Science and Technology, 22 collaborators from across the U.S. contributed data to help determine methylmercury levels in 3,200 individual amphibians, representing 14 species from 26 populations.
“There’s been a lot of work on mercury in different taxa, including experimental studies, but what hasn’t been done is a both geographically and taxonomically large study with amphibians that’s comprehensive and at a national scale,” said USGS biologist with the Northern Rocky Mountain Science Center, Brian Tornabene, the study’s lead author.
Gulf coast waterdogs had some of the highest amounts of methylmercury in their systems compared to other U.S. amphibians. Credit: Brad M. Glorioso
All of the research was collected in nonlethal ways as part of long-term studies. One strategy involved determining mercury levels in dragonflies that occupied the same areas as amphibian species. “Dragonflies could be used as an indicator of bioaccumulation. And this is especially important for vertebrate species that are hard to capture, rare, or, more importantly, if they’re endangered species that we want to limit our influence on,” Tornabene said.
The researchers found a 33-fold difference in methylmercury concentrations in amphibians across sites and some key differences between species. Salamanders generally had higher levels than frogs, with the highest concentrations in species like Gulf Coast waterdogs (Necturus beyeri) and mudpuppies (Necturus maculosus) in Louisiana and two-lined salamanders (Eurycea bislineata) in Maine. Those with the lowest mercury levels included western toads (Anaxyrus boreas) in Montana and the Oregon spotted frog (Rana pretiosa) in Oregon and the California red-legged frog (Rana draytonii) in California.
“This is kind of a jumping-off point,” Tornabene said. “Before we had a limited look at methylmercury in populations across the country. Now, we have more of an in-depth look, and we’ve identified some populations that have higher methylmercury than others.”
This can help researchers identify sensitive populations, he said. When experimental studies nail down what levels might put species at risk, scientists can return to this study to see which populations have reached these levels or resample them to see how levels have changed.
“We hope to use the information reported in this first paper to estimate how methylmercury affects vital rates, such as survival, of adult amphibians at a subset of sites,” said Blake Hossack, a research zoologist at the USGS Northern Rocky Mountain Science Center and principal investigator of the paper.
Tornabene said high levels of mercury in amphibians is concerning as it can bioaccumulate and biomagnify up the food chain, so other animals that eat them could build up higher mercury levels.
“There’s also a potential for movement of methylmercury,” he said, meaning the toxin could travel in the amphibians from aquatic habitats to contaminate organisms in terrestrial ones.
Researchers are deploying remote cameras with artificial intelligence capabilities in India to reduce conflicts between tigers and livestock.
Tiger (Panthera tigris) populations have been so successful in rebounding in India that they are leaving reserves and getting into close contact with people. Remote camera images have shown tigers walking within 100 meters of homes. That doesn’t just pose a danger to people. The roaming cats sometimes prey on their livestock, affecting their livelihoods.
“Where we’re working, tigers are killing livestock on almost a daily basis,” said Jeremy Dertien, a postdoctoral researcher at the German Center for Integrative Biodiversity Research. The residents have proven “amazingly resilient” in the face of the roaming cats, Dertien, but being able to keep track of the tigers could help them coexist.
The TrailGuard AI camera system, shown alongside a nightjar for scale, can be camouflaged near a trail. Credit: Jeremy Dertien
As a postdoc at Clemson University, Dertien and his colleagues employed special cameras with an artificial intelligence component to keep track of the tigers and alert people when the cats are near. Clemson researchers, in collaboration with the Global Tiger Forum, worked with the organization RESOLVE on a team led by Eric Dinerstein that spent seven years developing the cameras before deploying them in India.
About the size of an extra-large Sharpie pen, the TrailGuard AI camera is placed up to three meters off the ground. When its embedded AI detects an animal it suspects is a tiger, it sends the tiger image to a computer server and via email or Telegram to a park ranger.
In a study published in BioScience, Dertien and his colleagues first tested the AI tiger model to see if it would decipher that it took a picture of a tiger and how long it would take to do so. In the vital Kanha–Pench corridor of central India, the team determined that it worked, taking 30 to 45 seconds from detection to deliver the notification.
Dertien joins a forest guard installing a camera on a tree. Courtesy Jeremy Dertien
Since then, the cameras have been put into action. “The rangers have been asking for more cameras to be deployed out there because it really helps them keep track of some problem tigers they might have,” Dertien said.
Rangers have used WhatsApp groups with village leaders to let them know the general area tigers are roaming, in case people may have their livestock out. “People actually get on bikes and blow horns” to warn local residents, Dertien said.
The devices are also being put to work elsewhere, in different ways. In parts of Africa, they’re being used primarily to detect poachers rather than wildlife.
Mount Graham red squirrel numbers decreased this year in southeastern Arizona, according to the most recent survey. Conducted jointly by the Arizona Game and Fish Department, Coronado National Forest and the U.S. Fish and Wildlife Service, the survey estimated 144 squirrels in the Pinaleño Mountains. This is an increase from the 109 squirrels estimated in 2021, but lower than the 156 squirrels estimated after a new survey method was implemented in 2022.
“The numbers this year demonstrate that we need to continue working together to manage the squirrels’ habitat and help the subspecies recover,” said Marit Alanen, lead biologist for the Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) with the U.S. Fish and Wildlife Service.
The endangered squirrel’s population peaked in the late 1990s. The 2017 Frye Fire devastated much of their habitat. Other long-term impacts include insect infestations, competition with nonnative squirrels, and poor cone crops caused by drought.
Pollution may be compounding the risks of climate change for green sea turtles. Because sea temperature determines the sex of the reptiles, warming temperatures are causing more females to be born. In the Great Barrier Reef, hundreds of females are born for every male. But researchers have found that pollution may skew the sex ratio toward females even further.
Studying green sea turtles (Chelonia mydas) in Australia, researchers found that some heavy metals and organic contaminants mimic the function of the hormone estrogen, tending to redirect developing embryos toward females. That raises concerns about the ability of the turtles, listed as endangered by the International Union for Conservation of Nature, to persist.
“As the sex ratio gets closer to 100% females, it will get harder and harder for adult female turtles to find a mate,” said Arthur Barraza, a researcher at the Australian Rivers Institute at Griffith University and first author of a new study in Frontiers in Marine Science. “This becomes especially important as climate change will continue to make nesting beaches warmer and more female-biased.”
