Black Bear Biology

Nothing New Under The Sun

The Osage author John Joseph Mathews once wrote that, other than hunters, the coyote’s only real enemies were those of a “microscopical” form, referring to pathogens and disease. “Every species has such enemies,” he wrote. “[And] such enemies are a part, a very important part, of the balance, and are not only invisible but mysterious to me.” Like Mathews, I find the microscopical enemies of wildlife both mysterious and fascinating. So much so that I have dedicated my professional life to understanding and managing them, but I am not just a wildlife veterinarian. I am a hunter, a wife, and a mother trying to live field-to-table like so many others. From that perspective, I can’t help but notice that outdoor media is increasingly inundated with disease-related information, and many of my fellow hunters seem thoroughly burned out on the subject. Who can blame them, really? So, what’s the deal with all the disease stuff? Is it hype or a good old fashioned sign of the end times? As usual, the truth lies somewhere in between. 

Disease was once considered to be a normal part of wildlife ecology that rarely, if ever, required intervention. That perception was based largely on an unwavering faith in the adaptability of species and the misconception that disease transmission naturally stops when outbreaks reduce population densities. In recent decades, it’s become clear that disease can be a major threat to wildlife conservation, having driven declines and extinctions worldwide. Add to that a growing awareness of wildlife pathogens as a threat to human health, and you have the perfect recipe for an explosion of trendy disease research. On the plus side, our understanding of these issues has grown exponentially, with many genuine benefits to the cause of conservation. Conversely, as new science spills into the popular press, it can be difficult to filter out what’s important. It’s true that not every disease has serious implications for wildlife managers or hunters. Many are a normal part of species’ ecology, but it's equally true that some diseases have genuinely ominous implications, usually falling into three categories: public health, food security, or conservation. 

The classic bear parasite Trichinella spiralis is a good example of a pathogen that is significant almost exclusively for public health reasons. The parasite itself causes no disease in bears, mountain lions, or a multitude of other animal hosts, but serious issues arise in humans unfortunate enough to consume undercooked meat from infected game. Once prevalent in commercial swine, the parasite was well known to previous generations, like my mother who considers “floppy” bacon a near-death experience, but younger generations and new hunters may be less familiar with the food handling practices needed to mitigate this concern. To complicate the issue further, species of Trichinella found in the far north require different precautions than those found at lower latitudes. Although research on Trichinella continues, a lot of it leans to the academic side, and media campaigns targeting hunters are largely intended to maintain awareness as hunting communities diversify and hunters become more mobile. 

Some wildlife diseases garner attention for the risk they pose to livestock and commercial food supplies. One timely example is the highly pathogenic avian influenza (HPAI). Starting as a mild strain of flu in wild waterfowl, this virus increased in its ability to cause severe disease as it shuffled back and forth between domestic poultry and wild birds in Asia. It made its way around the world on the wings of migrating ducks and geese, reaching the U.S. in late 2021. HPAI has affected over 800 poultry flocks in 47 states, with a loss of more than 58 million domestic birds. Waterfowl hunters reported geese falling from the sky during the peak of the 2022-2023 season, and a wide range of other species were exposed to HPAI by eating infected birds. Infections were reported in everything from bald eagles to marine mammals, including black bears in multiple states. At this point, there’s no evidence that HPAI is circulating in bear populations or being passed from bear to bear, but every new species infected is an opportunity for the virus to evolve and adapt. 

The unfortunate truth is that some diseases are a genuine threat to the health and stability of wildlife populations. Although wildlife have a phenomenal ability to adapt to new challenges, including diseases, adaptive potential is not a panacea against all evils. Sarcoptic mange is a disease that has seriously impacted wildlife populations around the world and is an emerging disease issue for black bears in parts of the eastern and central U.S. The condition is caused by a mite that infests the skin, resulting in inflammation and hair loss. Many animals recover on their own, while others progress to a pitiful and lethal state. Although the mite has been present throughout the black bear range for generations, the relatively recent emergence of clinical disease in some populations indicates a change in the balance between host, pathogen, and environment. The factor, or factors, driving that change and the risk to bear populations requires further investigation. 

Coming back to our original question, why are hunters being bombarded with information about wildlife diseases? It’s complicated. We’re living in a rapidly changing world with land use practices that encourage disease emergence and global commerce that spreads them with startling efficiency. Increased awareness, funding opportunities, and new technologies facilitate additional research, and current trends in science push researchers to share findings publicly that would have historically ended up in research journals and ivory towers. Admittedly, I’m not sure there is a solution for all of this. Certainly, global land use and commerce are more than we can tackle in one article, but a significant onus can be placed on scientists to be judicious in their messaging. The trend toward open science communication is a positive one, but it comes with a responsibility to present science with context and meaningful application, avoiding sensationalism at all cost. As hunters, we may also have to acknowledge that wildlife disease is going to be part of the conservation conversation moving forward.  

My best advice is to hang in there and rest assured that wildlife managers are just as tired of talking about diseases as you are of hearing about them. But we can look for common ground in wanting what is best for the wildlife resource; this means addressing whatever challenges they face, be it disease, habitat loss, or something else. I would ask every conservationist to remain vigilant of wildlife health when in the field, report anything that seems unusual, and support conservation efforts that take a holistic approach to species management. That is our best bet for resilient wildlife populations in the future.