Photo by Andrew King, USFWS.

May 3, 2021

Wildlife Research News

Keeping up with cutting-edge wildlife research, as well as changes in state and national wildlife-oriented programs and legislation, can be a daunting task. Here we briefly summarize some of the key work taking place that will be of interest to wildlife enthusiasts.

Bald Eagle Populations Quadrupled in a Decade

The U.S. Fish and Wildlife Service recently released the USFWS Final Report: Bald Eagle Population Size: 2020 Update which cites the current bald eagle population at 316,700 individual birds in the lower 48 states. The current population is a remarkable conservation success story considering that in 1963 the bald eagle population in the lower 48 states consisted of 417 known nesting pairs. Today, more than 71,400 nesting pairs exist. Data for the report was collected by USFWS biologists and observers throughout the country.

How Mammals Avoid Getting Caught Sleeping

A red fox sleeps in a sunny grassy spot. Its nose is resting on a short cut lawn.
Photo by Lachlan Gowen.

To learn how wild, sleeping mammals have adapted to keep themselves from being prey, researchers at the University of California, Santa Cruz, examined 230 papers covering sleeping mammals in nine mammalian orders, including ungulates, cetaceans, rodents, primates, bats and others. While strategies for recharging varied greatly among mammals, they could be divided into four overarching categories: 1. specialized forms of sleep, such as sleeping with one eye open, or keeping one side of their brain turned on (dolphins and seals), or suppressing their need for sleep to a few hours a day (some ungulates); 2. sleeping when predators are active as the animal will be less visible; 3. sleeping in burrows dug into the ground, in nests or high up in the trees; 4. employing a group sleeping strategy where some animals sleep while others—of the same species or sometimes of different species—keep an eye out for danger (giraffe herds). Evolutionary history, the environment and position in the food web are major drivers in developing sleeping strategies. All strategies could be affected by human disturbance such as light pollution, noise from traffic or problems of limited resources from habitat loss.

White-nose Syndrome Challenge Winner Announced

The deadly Pseudogymnoascus destructans fungus is spreading across the U.S. and Canada, causing a disease known as white-nose syndrome and killing millions of bats. In 2019, the U.S. Fish and Wildlife Service and the White-nose Syndrome Response Team launched a White-nose Syndrome Challenge to help destroy P. destructans and give hibernating bats in North America a fighting chance at survival. The Challenge sought innovative ideas to permanently eliminate, disarm or weaken P. destructans in the wild, without harming other beneficial species or the environment. In total, 47 teams from a variety of backgrounds submitted applications—including a high school science team. Applications were judged by the Service and a panel of experts. A graduate student and a post-doctoral student led the winning team from Oregon State University and the University of California. Working with experts in genomics, bioinformatics, plant pathology, mycology and vertebrate ecology, the group conceived of an aerosol spray to genetically silence the fungus that causes white-nose syndrome. By targeting the fungus itself, the team’s idea seeks to treat white-nose syndrome without harming the bats, the places they hibernate, or other organisms. For more information visit

Studying Coyote and Fox Population Trends in Illinois

A recent University of Illinois Illinois Natural History Survey study published in the Journal of Wildlife Management, that was funded by the Federal Aid in Wildlife Restoration Program, summarized information from trapper questionnaire data from 1976 to 2018 in statistical models to glean information on coyote and red and gray fox populations in Illinois. After controlling for confounding factors, such as gas prices and unemployment rates, annual trapper harvest and the number of animals harvested per trapper dwindled over time for red and gray foxes and increased for coyotes, which is consistent with what is known about long-term population changes of these species in Illinois. This information is important to guide state hunting and trapping regulations, study species’ declines and management of wildlife.

Fawn Survival Rates Unchanged by Lack of Predators

A spotted white-tailed deer fawn rests curled up in the understory of a forest. Green, lush vegetation surrounds the fawn.
Photos courtesy of IDNR.

Researchers working on a long-term white-tailed deer fawn study in Delaware found similar fawn survival rates in ecosystems without predators as in areas with coyotes, bobcats and black bears. Published in Ecosphere researchers determined that fawn survival occurred at the same rate in predator-free ecosystems as in ecosystems with predators such as in Pennsylvania, Minnesota and Missouri. Aside from fawns that died from emaciation, young deer experienced all kinds of natural mortality, including pneumonia, birth defects and tick-borne diseases. The main predictors of survival for the fawns were age of the doe, rainfall and birth weight.

Public Lands Insufficient Enough to Protect Endangered Species

A report in Scientific Reports states that even if all state and federal public lands in the United States were protected to benefit endangered species, more than half the country’s endangered species would still be in danger of extinction. Using computer modeling to determine the ability of public lands to protect federally listed species, researchers found that of the 159 endangered mammal, bird, reptile and amphibian species across the continental U.S., only 21 (13 percent) occur within lands set aside for wildlife conservation. Even if all public lands in the country were managed to protect wildlife, only 43 percent of endangered species would be conserved. As a result, private landowners must be encouraged to implement conservation practices that provide economic benefits while protecting wildlife.

Beavers Create Fire-resistant Forest Patches

A brown, damp beaver forages on the water's edge of a wetland. Green grass and vegetation is in the background.
Photo by Hans Benn.

A study published in Ecological Applications reports that a beavers’ ecosystem could build the resilience of riparian vegetation to wildfire flames. Examination of satellite images of areas having experienced five major fires showed 1,500 beaver dams, and that fires did not burn too intensely—on average three times less than areas without beavers.

Camera Traps to Detect Mange in Coyotes

In a presentation at The Wildlife Society’s 2020 Virtual Conference, researchers at Lincoln Park Zoo’s Urban Wildlife Institute reported that camera traps can be used in the surveillance of wildlife diseases. The study focused on coyotes in downtown Chicago to see if they could detect sarcoptic mange, a disease caused by a mite that burrows into the coyote’s skin, causing itchy lesions and hair loss. Analyzing almost 4,000 images of coyotes collected from the spring of 2010 to the winter of 2014, researchers found that 213 (5 percent) images depicted a coyote with mange. Coyotes were detected at 79 percent of the camera trap sites, with mangy coyotes at 39 percent of them. Further analysis found that coyotes with mange were more likely to occupy low density urban areas that had high canopy cover and were likely taking advantage of human-sourced food near homes and cover from forested areas. Researchers hope to continue the research, working with red foxes and gray foxes.

Bird Numbers Change with the Weather

How do migration distance, diet, the rarity of a species, foraging strategy and nesting location impact bird numbers in response to extreme weather? Using NASA satellite data and 15 years of data from eBird, a citizen science data collection process, researchers published a study in Global Change Biology on 109 bird species across eastern North America. Some species didn’t seem affected by extreme weather, but others were impacted greatly. Resident species, such as northern cardinals, chickadees and blue jays, as well as birds that only migrated within the United States, including eastern bluebirds, yellow-bellied sapsuckers, northern flickers and numerous species of sparrows, occurred less often when there was extreme weather. Dry conditions mostly affected less common species, which tend to be more specialized and eat one food source or live in one type of habitat.

Songbird Parents Give Nestlings the Boot

A study published in the Proceedings of the National Academy of Sciences, found that nestlings of 12 of 18 songbird species occurring in various habitats throughout the United States were about 14 percent less likely to survive when they left the nest too early. If chicks suffer when they leave the nest too early, why do parents kick them out? Researchers report that the longer chicks stay in the nest, the greater the chance the brood will be lost to predators, such as snakes or raccoons. By physically separating chicks outside the nest, parent birds decrease the probability of all nestlings dying to almost zero. The first study to compare survival rates before and after fledging across species and locations, it provides important information on the survival or life histories during this stage of life.

Monarch Butterfly Endangered Species Status Warranted but Precluded

An orange, yellow, black, and white monarch butterfly nectars on a cluster of pinkish, white milkweed flowers.
Photo by Daina Krumins.

Studying the monarch butterfly for 20 years, scientists have noted declines in populations wintering in Mexico and California. After receiving a petition to list the species in 2014, the U.S. Fish and Wildlife Service began an in-depth review, resulting in the recent finding that adding the monarch butterfly to the list of threatened and endangered species is warranted but precluded by work on higher-priority listing actions. A rigorous, transparent, science-based process was utilized in making the decision. For the immediate future, the Service will assess the monarch’s status annually until it is no longer a candidate. The Service also will work with partners to conserve the monarch and its habitat at the local, regional and national levels. For more information visit

Map of Global Bee Species

Researchers have created the first map of bee diversity, using almost 6 million public records of bee species locations. The findings were reported in the journal Current Biology. In mapping the world’s 20,000 species of bees, researchers found that the United States has the most species of bees—by far—and that there are more species of bees in the Northern Hemisphere than the Southern Hemisphere. There also are more bees in arid and temperate environments than in the tropics. The information can be accessed at Developing a baseline on bee populations will help scientists interpret abundance, species richness and geographic patterns, and ultimately help in the conservation of bees as global pollinators.

Pollution Regulations Protecting People and Birds

Scientists at Cornell and the University of Oregon report that pollution regulations designed to protect people are also benefitting North America’s birds. According to a report published in the Proceedings of the National Academy of Sciences, a federal program to reduce ozone pollution may have averted the loss of 1.5 billion birds—or nearly 20 percent of the bird life in the United States—during the past 40 years. The research entailed developed models utilizing eBird data, ground-level pollution data and pollution regulations.

Neurological Disease Killing Bald Eagles

Scientists have determined that a neurological disease—avian vacuolar myelinopathy (AVM)—that has been killing bald eagles and other birds in the U.S. for more than 25 years appears to be caused by a cyanobacteria growing on the leaves of the invasive aquatic plant Hydrilla verticillate. The disease causes birds to lose their navigation skills and they eventually are unable to fly, or they crash into trees. Researchers from the University of Georgia, along with scientists in Germany and the Czech Republic, reported in the journal Science found that A. hydrillicola only produces the toxin that causes AVM when it is around bromide, the negatively charged version of the element bromine. Bromide exists naturally in a lot of places and occurs in many synthetic chemicals that could find their way into the aquatic environment. Cyanobacteria, also called blue-green algae, are often dangerous to humans and other animals. The toxin can accumulate in birds, reptiles, fish and amphibians.

Our Well-being Can Be Attributed to Hearing Birds Sing

A meadowlark with white, black, and yellow feathers is in mid-birdsong while perching on a fence post.
Photo by Jeffrey Hamilton.

A recent study, published in Proceedings of the Royal Society B, summarized how Colorado hikers responded to birdsongs. Along two trails the research team hid speakers that played birdsongs, placing the speakers at the heights where the sounds would normally occur. Sounds were played at a time that did not interfere with the breeding season. Researchers interviewed hikers passing through the area, asking questions about their sense of well-being and perceptions of biodiversity. While the recording was on people had higher levels of well-being and perceived more biodiversity than they did without the recording. Researchers feel the observed reactions have implications for conservation, demonstrating that people receive something back from nature, and that wild areas are important places for the public.

Devices Deterring Wildlife from Wind Energy Facilities

Wind energy facilities have been documented as causing fatalities when eagles and other wildlife get struck by the blades. Working to combat these losses, new devices, called the IdentiFlight system, have been designed to attempt to mitigate the losses. The test system involved eight cameras recording the area around wind turbines as well as artificial intelligence algorithms programmed to recognize large raptors. Turbines were programmed to turn off when birds got too close. A study published in the Journal of Applied Ecology compared the number of eagles killed at the sites with results of statistical models used to determine how many might have died without detection. The number of birds killed at one site dropped by 60 percent after installation of the IdentiFlight system while the number of deaths increased at the second site, which researchers surmised may have been due to a higher eagle population.

Location Does Not Lower Bears’ Survival Rates

In a study published in Animal Conservation, Illinois Natural History Survey scientists report that translocating black bears that were damaging property or crops did not lower their survival rates. The study reviewed data on 1,233 American black bears translocated in Wisconsin between 1979 and 2016. Most of the bears were moved because of nuisance complaints. Scientists expected that the translocated bears would have a higher mortality rate because of unfamiliar landscapes, road mortality, problems with other bears and traveling long distances to find food. Data indicated that bears translocated longer distances had a higher survival rate, possibly because they were less likely to repeat nuisance behaviors. Releases in national forests and large natural areas also minimized chances for nuisance behaviors.

Are Bat Boxes Beneficial?

Two black bat boxes are installed on the side of the house on the wooden siding near the roof. In the background is a blue sky and trees.
Photo by Rose Primmer, USFWS.

University of Illinois researchers published an article, “Avoiding a conservation pitfall: Considering the risks of unsuitably hot bat boxes,” in Conservation Science and Practice that recommends careful selection of bat box design and location is needed to prevent bats and their pups from overheating and dying. Small, darkly painted bat boxes heat quickly—bats are significantly heat-stressed above 104 degrees Fahrenheit—and likely hurt bats if placed in the wrong location. Researchers have recorded temperatures as high as 142 degrees Fahrenheit in artificial roosts. Bats have been observed moving from natural roosts to avoid temperatures above 97 degrees. Researchers advocate for not painting boxes dark colors and to supply boxes of a larger design so bats can change locations within the box during the day. They also recommend that small, dark bat houses not be placed where they will receive full sun all day. Rather than boxes, homeowners are encouraged to leave dead-standing trees, plant native wildflowers and trees that attract insect prey, and provide clean water sources.

Missouri White-tail Sets Record for the Longest Movement

In November 2017, a three-year old buck equipped with a GPS collar started on a trip from a rural area north of Kansas City, Missouri and in 11 months it traveled about 300 kilometers (186 miles). Published in Ecology and Evolution, the study reports that adult deer rarely move far, usually only in the order of tens of kilometers. Researchers were surprised by the number of interstate and highway crossings the deer made, and that it traveled so far during the hunting season. The journey raises more questions than answers and could have implications for the management of chronic wasting disease.

Kathy Andrews Wright is retired from the Illinois Department of Natural Resources where she was editor of Outdoor Illinois magazine. She is currently the editor of Outdoor Illinois Wildlife Journal and Illinois Audubon magazine.

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