Erika Machtinger has a lot of questions as to what is causing a mange epidemic in Pennsylvania’s black bears.
In two years, she hopes to have answers and possibly a solution.
Machtinger, who is an assistant professor of entomology at Penn State University and a certified wildlife biologist, is spearheading a joint study with the Pennsylvania Game Commission that will track 36 radio-collared bears. A dozen of the bruins will be normal and mange-free, 12 more will be bears with a moderate case of mange and the other group will be bears that have mange and will be treated with Ivermectin, a medication used to treat animals with parasites.
“Over a two-year period we’ll see how many of those bears’ mange cases resolve on their own, how many resolve with treatment, and how many bears come down with mange,” Machtinger said. “That should give us an idea of how mange affects denning and potential reproduction, and that ultimately should show how mange actually is affecting the bear population. We’ll also see how mange may affect bear movement, home range size, and use of human habitats.”
Mange is a highly contagious skin disease caused by parasitic mites that results in hair loss and sometimes emaciation and death. Mange has occurred in black bears for the last two decades, Machtinger said, but not to the extent seen over the last five years.
In 2014, Game Commission personnel euthanized 56 bears for mange across the state, and several more were brought to check stations by hunters. Game Commission bear biologist Mark Ternent estimated in 2015 the percentage of bears with mange to be between 3 and 12 percent, and most of those cases are in the northcentral part of the state.
Mange has long been a somewhat common occurrence in coyotes and foxes, and it appears the same species of mite that affects canines is also causing the current problem with bears.
Machtinger said a joint study between the PGC and University of Georgia showed the same mites impacting foxes and coyotes was also found on bears, meaning the mites may have been able to jump species and have become adapted to bears.
“It’s likely that bears pick it up from foxes and coyotes. That could be the result of land-use changes that are putting bears where coyotes and foxes hang out,” Machtinger said. “We want to work with the Game Commission to try to figure out what’s going on. Different species of skin mites can be found in bears in other states but this severe outbreak of sarcoptic mange is a unique Pennsylvania situation.”
One potential issue with using Ivermectin on bears is the medication usually requires follow treatments when used on dogs. That can be tough to do with bears. When Game Commission staff traps a bear with a case of mange it is often treated with Ivermectin, and Machtinger said the study should provide an answer if the single treatments are working.
“We’re also going to see how many mange cases resolve without treatment and why. If Ivermectin is something that’s not working, we’re not sure how that will be addressed yet,” she said.
Blood and tissue samples from trapped bears will be analyzed to learn more about the immune functions between healthy bears and those with mange. Other parasites, such as ticks and lice, will be studied as well. The is evidence that immune-suppressed animals are more susceptible to parasites.
Normally, most bears that are exposed to mites may have a dermal response, but after the initial reaction their immune system can fight the parasites off.
“But that doesn’t seem to be happening with sarcoptic mange in some bears in Pennsylvania,” Machtinger said. “And we need to find out why.
“Mange isn’t devastating the bear population, but it is an animal welfare concern.”