Fibromas

This buck shows half a dozen wart-like fibromas in his skin.

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A friend and I came out of my garage to find two buck mule deer, still in velvet, eyeing my new aspen tree. As we stepped up on the porch, they cautiously moved across the road onto the neighbor’s place and I breathed a sigh of relief. My aspen was safe, tenuously, again. As we watched the bucks, we noticed that the larger of the two had a tennis ball-sized growth hanging pendulously from his neck. Closer inspection revealed several other large black growths on his chest and shoulder and a couple on his side. Although he didn’t seem bothered by the growths and was as fit looking as his companion, we wondered what impact they might have on his health.

This isn’t the first time I have seen growths on wildlife. It seems that they are common on deer, both mule and whitetail, but I have seen them on elk and moose as well. I also have seen them on rabbits and hares, and a couple of times on birds.

These growths are called fibromas. They are wart-like growths, and like warts, are caused by viruses—in the case of wildlife, pox and papilloma viruses. Sometimes they are called, papillomas. They are growths of the skin and rarely extend into the muscle. Those on the deer we saw were black, but they can be gray or tan as well. Also, the surface of the fibromas on the buck we watched seemed to be coarse, but the texture can vary from soft to dry, smooth to as rough as a cauliflower head. It is most common for fibromas to be centered around the head and legs, but they can be anywhere on the body, including in the oral cavity. According to Cornell University Scholl of Veterinary Medicine, fibromas are typically spread through direct contact with a bleeding fibroma or through the bite of bloodsucking insects like mosquitoes.

There are two big elephants in the room when discussing fibromas in animals. The first is whether or not it is harmful to the animals. The fibromas themselves are not cancerous and other than a small energy demand, do not seem to injure the animals other than perhaps being uncomfortable or inconvenient. However, a heavily infected animal can have 100 or more tumors, from a 10 to 100 millimeters in size.  I did an internet search for photos of deer with fibromas and saw some pretty gross images of heavily infected deer. With a big infestation, the fibromas may interfere with feeding, breathing, locomotion and/or sight, any one of which can lead to death.

There is no treatment for fibromas and since they don’t impact species on a population level, no treatment is warranted. On the positive side, “The growths are generally self-limiting and regress on their own as infected animals mount an immune response (Cornell University).” Once an animal has fought off an infection, it may be immune to further attack.

The second elephant is whether or not such an infected deer, rabbit, squirrel or whatever, is a hazard to humans or other animals, and is the flesh still consumable. The viruses that cause fibromas are species specific, meaning that those that attack deer cannot attack rabbits or coyotes or dogs or humans. They are also restricted to the skin and are removed with the skin. If a lesion does adhere to the muscle beneath, simply cut around it and discard that meat with the hide and the meat should be fine to consume.

It is easy to think that our wildlife live in a sort of Utopia, without concerns. Nothing could be further from the truth. This was a good reminder that it is a tough old world out there and wildlife face challenges of many kinds. 

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Help Idaho Wildlife

When we traveled across the state in October 2017, most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.